Article: 218225 of rec.radio.amateur.antenna From: Ari Silversteinn Subject: Re: Emergency Messaging, AM/FM *On Locomotive* Date: Fri, 7 Oct 2005 12:43:50 -0400 Message-ID: <8fyjcagnbyos$.ciygv6f9ygga.dlg@40tude.net> References: <11615-4343E2C5-53@storefull-3251.bay.webtv.net> <61th13-nok.ln1@fimbul.myth> On Fri, 7 Oct 2005 02:51:02 -0700, Jim Richardson wrote: >>> Air horns as used on locomotives are designed to get attention. They are >>> heard at great distances. >> >> Ever hear of The Quiet Zone rulings? > > you expect to get a special dispensation to blast all bands in an > emergency, but worry about noise ordinances? Quiet Zones are no horns allowed. The rest you have to figure out. -- Drop the alphabet for email Article: 218226 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: assymetrical antenna Date: Fri, 7 Oct 2005 11:36:34 -0500 Message-ID: <9656-4346A412-598@storefull-3254.bay.webtv.net> References: Myron Calhoun wrote: "Wasn`t the design criteria something like "Make it 40 feet high, and feed it 40 feet off center." The Windom was named for the amateur who described it in an article. It was a 1/2-wavelengrh at its lowest frequency of use. A single feed wire is connected at 0.34 X the length of the antenna, from one end. The Windom works best over highly conductive earth using a versatile matching network to the transmitter. The 1/3 length feedpoint from one end is about 1/6 the distance from the antenna`s centerpoint. 40 feet off center, makes the antenna 240 feet long. This is 1/2-WL at 146 meters. It is 12 meters high. This is 1/4-WL at 48 meters and 1/2-WL at 24 meters. Best regards, Richard Harrison, KB5WZI Article: 218227 of rec.radio.amateur.antenna From: "RJ" Subject: Hustler 3 antenna (VP-3) adjustment Message-ID: Date: Fri, 07 Oct 2005 16:46:03 GMT I have a Hustler mobile mast with a VP-3 mount using a 10, 20 and 40 meter resonator. Anyone know about the sequence for tuning these 3 antennas? I have misplaced my instruction sheet. Tnx Bob, AA8X Article: 218228 of rec.radio.amateur.antenna From: Ari Silversteinn Subject: Re: Emergency Messaging, AM/FM *On Locomotive* Date: Fri, 7 Oct 2005 12:48:42 -0400 Message-ID: <1sgoknd8029uu$.19z9gfqusx7lm$.dlg@40tude.net> References: <11615-4343E2C5-53@storefull-3251.bay.webtv.net> <4ntbk1lua9jmglj5gthnj6d889k0o8nsg0@4ax.com> On Fri, 07 Oct 2005 00:39:11 -0400, J. Teske wrote: > If an On-Star device, would be true two way, with GPS tracking, with > either end of the link able to activate the system. One could > broadcast a message to every active unit, either universally, or, > based upon GPS tracking to every unit with prescribed geo coordinates. > There already exists a somewhat similar system to broadcast weather > alerts to a passive receiver, although not normally deployed in cars. > Boaters already can have a Digital Selective Calling VHF radio in > their boats by which a coast guard can issue warnings. Such a system > is being mandated in the UK by a phase in process (e.g. new radios > with the old paradigm cannot be marketed unless they have DSC.) > > And horror of horrors, one could alway investigate Broadband over > Powerlines (BPL). Wouldn't that give us hams some gas. > > W3JT The issue of installing a proprietary receiving device inside automobiles, mandated by federal action, is one that is being given serious conversation. The one problem that appears to be an issue is the liability one. It will be a matter of time that someone will sue saying that the system scared them or distracted them and caused this or tat accident. -- Drop the alphabet for email Article: 218229 of rec.radio.amateur.antenna From: Me Subject: Re: Emergency Messaging, AM/FM *On Locomotive* References: <11615-4343E2C5-53@storefull-3251.bay.webtv.net> <4ntbk1lua9jmglj5gthnj6d889k0o8nsg0@4ax.com> <46hck11f47qhnt2lpspb4jhvpigkpras18@4ax.com> Message-ID: Date: Fri, 07 Oct 2005 16:50:37 GMT In article <46hck11f47qhnt2lpspb4jhvpigkpras18@4ax.com>, kashe@sonic.net wrote: > On Fri, 07 Oct 2005 00:39:11 -0400, J. Teske > wrote: > > >On Thu, 6 Oct 2005 18:38:04 -0400, Ari Silversteinn > > wrote: > > > >I don't know the details on how it works, but it seems to me that a > >broadening of something akin to the On-Star technology might be a > >solution work examining. I do not know if an On-Star operator can talk > >to an equipped vehicle at On-Stars initiative, but certainly we have > >the start of a system with a two-way radio with a satellite comms > >link. > > Why not -- they can eavesdrop on a selected vehicle, as was > proven once when the cops asked them to do so to a vehicle involved in > a kidnap. > > And now thwt I think of it, they can iniiate a conversation > when they detect an airbag deployment. OnStar is a cellular based system with GPS Positioning builtin Me Article: 218230 of rec.radio.amateur.antenna From: Ari Silversteinn Subject: Re: Emergency Messaging, AM/FM *On Locomotive* Date: Fri, 7 Oct 2005 13:23:46 -0400 Message-ID: References: <4ntbk1lua9jmglj5gthnj6d889k0o8nsg0@4ax.com> <1406-43468745-509@storefull-3258.bay.webtv.net> On Fri, 7 Oct 2005 09:33:41 -0500, Richard Harrison wrote: > J. Teske wrote: > "Ever hear of Quiet Zone rulings?" > > Is that why air raid sirens aren`t tested Fridays at noon anymore? > > When life is at risk, quiet zones, like radio rules, don`t apply. Yep, you've never heard or understand Quiet Zones. -- Drop the alphabet for email Article: 218231 of rec.radio.amateur.antenna From: Jim Kelley Subject: Re: Emergency Messaging, AM/FM *On Locomotive* Date: Fri, 07 Oct 2005 12:20:30 -0700 Message-ID: References: <4ntbk1lua9jmglj5gthnj6d889k0o8nsg0@4ax.com> <1406-43468745-509@storefull-3258.bay.webtv.net> Ari Silversteinn wrote: > On Fri, 7 Oct 2005 09:33:41 -0500, Richard Harrison wrote: > > >>J. Teske wrote: >>"Ever hear of Quiet Zone rulings?" >> >>Is that why air raid sirens aren`t tested Fridays at noon anymore? >> >>When life is at risk, quiet zones, like radio rules, don`t apply. > > > Yep, you've never heard or understand Quiet Zones. Is a quiet zone a place like Placentia Ca. which had, for the railroad, become a manditory blow your full set of air horns long and loud right next to the bedroom windows every time you pass by no matter what time of day or night it is, and where the locals have passed an ordinance that says they're sick and tired of it? Article: 218232 of rec.radio.amateur.antenna From: Brian Howie Subject: Re: building a medium wave antenna for 60km area Date: Fri, 7 Oct 2005 19:58:04 +0100 Message-ID: References: <1128522515.542085.75070@g14g2000cwa.googlegroups.com> In message <1128522515.542085.75070@g14g2000cwa.googlegroups.com>, wadjet writes >Hello > >I would like to have some help. I have a school job to build a medium >wave antenna omnidirectional for a area 60km radius. the frequency of >the station is 999KHz. >Where can i find some material to do this. Just copy one of these :- http://tx.mb21.co.uk/gallery/westerglen.asp Brian -- Brian Howie Article: 218233 of rec.radio.amateur.antenna From: "hasan schiers" Subject: Trapping my 80m Inverted L for 160? Date: Fri, 7 Oct 2005 15:02:29 -0500 Message-ID: I'm having great success with my 80m inverted L (45' up and 25 or so feet out), with 26 radials (now). (Hung off the side of my tower) I had a thought for something to just "get me on" 160. Is there any reason I couldn't put an 80m trap (design freq, please?) at the end of the 80m horizontal wire and stretch it out for 160? I read the article on W8JI's site about coaxial vs other traps. Since I'm not going for broke, but just want a quick and dirty solution, I was thinking about making a coaxial trap for 80m out of RG8/X coax (or I could buy some 58a/u) that I have laying around. Not running more than 500w, so this size coax should be fine. My questions: 1. What freq should I "design" the trap for? 1a. The program referred to on W8JI's web site (trap design) has no entry for 8x, but manual values can be entered. Anyone have ready access to the parms for 8x that I need to enter? 2. I assume the trap will detune the 80m section, making it longer. Any ideas for a starting point on how much to shorten it, or should I just cut and try? 3. Will there be any degradation on performance on 80m from adding the trap and wire extension to enable 160m? 4. Any suggested starting wire length after the trap to resonate 160 towards the lower (DX) part of the band? I don't want to ruin the excellent performance I'm getting on 80m, no matter what I do, so if I can't do this without compromising 80m, I'll think about another alternative. Thanks for any ideas you may have. I wan't to get this done before the snow flies! 73, ...hasan, N0AN Article: 218234 of rec.radio.amateur.antenna From: Ari Silversteinn Subject: Re: Emergency Messaging, AM/FM *On Locomotive* Date: Fri, 7 Oct 2005 16:28:35 -0400 Message-ID: <81b62fvzkos0$.i8rapbwec17l$.dlg@40tude.net> References: <4ntbk1lua9jmglj5gthnj6d889k0o8nsg0@4ax.com> <1406-43468745-509@storefull-3258.bay.webtv.net> On Fri, 07 Oct 2005 12:20:30 -0700, Jim Kelley wrote: >> Yep, you've never heard or understand Quiet Zones. > > Is a quiet zone a place like Placentia Ca. which had, for the railroad, > become a manditory blow your full set of air horns long and loud right > next to the bedroom windows every time you pass by no matter what time > of day or night it is, and where the locals have passed an ordinance > that says they're sick and tired of it? Close. http://tinyurl.com/cb53f -- Drop the alphabet for email Article: 218235 of rec.radio.amateur.antenna From: Owen Duffy Subject: V/I ratio is forced to Z0 Message-ID: Date: Fri, 07 Oct 2005 20:29:06 GMT On Tue, 27 Sep 2005 02:04:46 GMT, Cecil Moore wrote: >The transmission line length must only be long enough such that >the V/I ratio is forced to the Z0 value. According to some pretty >smart guys I asked, that's about 2% of a wavelength. Cecil, do you have some quantitative explanation / support for this? The treatments that I have seen of transmission line tuners where different Zo lines are directly connected do not suggest corrections / tolerances of the type you imply. (IIRC, Terman discusses a fringing capacitance as a means of allowing for a physical discontinuity.) I am not asking whether or not field conditions (and V/I on the conductors) immediate to the discontinuity are not Zo of either of the lines, just where has the 2% of a wavelength come from? Owen -- Article: 218236 of rec.radio.amateur.antenna From: tclay@qmc.ph.msstate.edu Subject: Re: Trapping my 80m Inverted L for 160? Date: 07 Oct 2005 15:32:23 -0500 Message-ID: <87zmplyso8.fsf@qmc.ph.msstate.edu> References: >about coaxial vs other traps. Since I'm not going for broke, but just want a >quick and dirty solution, I was thinking about making a coaxial trap for 80m >out of RG8/X coax (or I could buy some 58a/u) that I have laying around. Not >running more than 500w, so this size coax should be fine. I did that once to make a dual-band inverted L, and it worked fine (I also used a coax-cable trap). I tuned the trap for 80m. Here is another alternative to think about that might be even easier: simply put up a second wire for 160m, and feed it in parallel with the 80m wire. For a while I had up a 160m inverted L with a vertical part of about 75'. I had a 80m wire (full 1/4 wave) running parallel to the 160m, and spaced about 3 feet away. At the base, they both connected to the feedpoint. I used a beta match coil across the feedpoint to match the 160 wire, which had little effect on the 80m swr. It worked quite well on both bands. Tor N4OGW Article: 218237 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: building a medium wave antenna for 60km area References: <1128522515.542085.75070@g14g2000cwa.googlegroups.com> Message-ID: Date: Fri, 07 Oct 2005 15:44:02 -0500 Assuming you really are wanting information and are not being silly! Generally speaking MF stations that want that kind of range in a average broadcast mode of operation (ie the people receiving it only have small portables/car radios etc rather than well tuned antenna arrays themselves) need to have something close to a 1/4 wave vertical in a very large paddock with an underground earth mat. You can use longer antennas and feed them as half waves etc but your dimensions become a problem. A 1/4 wave on 999kHz is 150 metres or thereabout. Thats roughly how high a guyed lattice tower/structure you would need. The ground mat would probably need to be at least 15 metres out from the antenna base. This is of course not cut and dry. Varying conditions and topography govern what kind of performance you will really get. Most MF stations also run quite a lot of RF power. Something you didnt specify. You can of course make a loaded antenna of any length and suffer the loss of performance. I cant remember the figure off hand but something like a 97% loss of antenna effiency wouldnt be unrealistic if you used a 6 metre loaded vertical. Probably your best "bang for buck" would be to float an antenna from a kite. There may be air regs to consider though. If you really are trying to do this pls repost some more detail of what you are trying to achieve. Bob VK2YQA wadjet wrote: > > Hello > > I would like to have some help. I have a school job to build a medium > wave antenna omnidirectional for a area 60km radius. the frequency of > the station is 999KHz. > Where can i find some material to do this. > > Tanks > Article: 218238 of rec.radio.amateur.antenna From: Ian Jackson Subject: Re: Connecting several bandpass filters. Date: Fri, 7 Oct 2005 22:17:24 +0100 Message-ID: <74jA3LZkXuRDFw7g@g3ohx.demon.co.uk> References: <43422d26$1@news.wineasy.se> <4342fba9_3@news1.prserv.net> With all those channels mixed together, it would be best to simply use an A/B switch to switch between the two antennas. Ian. In message <43436b5d$1@news.wineasy.se>, SH writes >Thanks for both you answers its nice to now i stil remember some theory >eventhough its 10 years since i read some UHF theory (Ended up being a >programmer :-)))) > >I think ill go for the notch version. I have made a lot of them and they are >easy to build but I've noticed that it seams that 3 notches (adjusted to 3 >diff freq.) is some kind of limit. When i put in no. 4 it seams that the >overall loss increases. >Do I remember correctly when i state that 2 nothes on the same freq. should >be a 1/4 wave apart??? > >Best regards > >Svend Holby > >"Crazy George" wrote in message >news:4342fba9_3@news1.prserv.net... >> Ben Jackson has some good points. You need not worry about audio, >> usually, >> as the FM capture takes care of the weaker signal. So, filtering the >> video >> carrier and near sidebands is all that is necessary. >> >> However, in answer to your question, the way you connect bandpass filters >> in >> parallel is with power dividers, amplifiers, and power dividers again, >> backwards as summers. Otherwise, controlling the out of band input and >> output impedances of several in parallel is a monumental, but solvable >> task. >> Spice, anyone? >> >> -- >> Crazy George >> "SH" wrote in message >> news:43422d26$1@news.wineasy.se... >>> Hi >>> >>> I have come up with one of those crazy DYI ideas which I would like to >> try >>> to implement but one thing still remains. >>> >>> I have two UHF (TV) arial pointing in different directions and would like >> to >>> connect them together through BP filters to minimize noise. >>> BP = Bandpass >>> Antenna 1: UHF channel (Europe) BP 1 ch 22-37, BP 2 ch40 -44, BP 3 ch >>> 49 - >>> 68/ or high pass >>> Antenna 2: UHF channel (Europe) BP 1 ch 21 / or low pass, BP 2 ch38 -39, >> BP >>> 3 ch 47 >>> >>> I have found formulas to design each section of BF but how to you connect >>> several BP filters in parallel??? I have investigated some old TV filter >> and >>> they have a coil (12 WDG) in and out of each BP section but is that the >> way >>> to do it and how does it influence the design of each BP. >>> >>> The only approach that I can find is to split the signal into three (- >> 6dB ) >>> then feed each into a BP filter and the Combine them again (-6dB). This >> will >>> result in each BP section seeing 75 Ohms as they shouland they would not >>> interfere with eachother. Ofcouse i would need a 20 dB amplifier to fix >> the >>> loss. >>> >>> But is there a better way. >>> >>> Best regards >>> >>> Svend Holby >>> >>> >> >> > > -- Article: 218239 of rec.radio.amateur.antenna From: Jim Kelley Subject: Re: V/I ratio is forced to Z0 Date: Fri, 07 Oct 2005 15:09:25 -0700 Message-ID: References: Owen Duffy wrote: > On Tue, 27 Sep 2005 02:04:46 GMT, Cecil Moore wrote: > > > >>The transmission line length must only be long enough such that >>the V/I ratio is forced to the Z0 value. According to some pretty >>smart guys I asked, that's about 2% of a wavelength. > > > Cecil, do you have some quantitative explanation / support for this? > > The treatments that I have seen of transmission line tuners where > different Zo lines are directly connected do not suggest corrections / > tolerances of the type you imply. > > (IIRC, Terman discusses a fringing capacitance as a means of allowing > for a physical discontinuity.) > > I am not asking whether or not field conditions (and V/I on the > conductors) immediate to the discontinuity are not Zo of either of the > lines, just where has the 2% of a wavelength come from? > > Owen As I recall it came from someone on sci.physics.electromag. But think about it. The surge impedance (Zo) is basically just the ratio of the capacitance per unit length to the inductance per unit length. Those quantities might vary a little bit from one place to another, but probably not by much. And there are undoubtedly end effects which locally pull the capacitance and inductance values away >from the ideal. So the length really need only be long enough for the variations to average out and for the total values to become large enough to swamp the end effects. ac6xg Article: 218240 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: V/I ratio is forced to Z0 Message-ID: References: Date: Fri, 07 Oct 2005 23:32:38 GMT On Fri, 07 Oct 2005 15:09:25 -0700, Jim Kelley wrote: >But think about it. The surge impedance (Zo) is basically just the >ratio of the capacitance per unit length to the inductance per unit >length. Those quantities might vary a little bit from one place to >another, but probably not by much. And there are undoubtedly end >effects which locally pull the capacitance and inductance values away >from the ideal. So the length really need only be long enough for the >variations to average out and for the total values to become large >enough to swamp the end effects. I don't doubt there is a discontinuity that disturbs the fields and V/I ratio. What I am asking about is the basis for the 2% of wavelength factor. If I use RG58C/U on 160m, I read that Cecil is suggesting that the V/I ratio is significiantly different to Zo for 2% * 160m or 3.2m (125")from the end of the cable, which seems large when the physical distance between the inner and outer conductor is 0.001m (0.04"). I am looking for quantitative support for Cecil's 2%. Owen -- Article: 218241 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: V/I ratio is forced to Z0 Date: Fri, 7 Oct 2005 23:38:08 +0000 (UTC) Message-ID: References: Definition of what you are all waffling about : "The input impedance Zo applies only for the duration of time taken for an echo to be received back from the point where the line impedance Zo first changes to another value.". Distance can be measured either in metres or, if you like, fractions of a wavelength. Wavelength involves frequency which is rather meaningless because time is already a variable but on a different arbitrary scale. Only Cecil could dream up a use for such an effect. ---- Reg, G4FGQ Article: 218242 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: building a medium wave antenna for 60km area References: <1128522515.542085.75070@g14g2000cwa.googlegroups.com> Message-ID: <14dj13-lfr.ln1@p400bob.personal.cox.net> Date: Fri, 07 Oct 2005 18:31:45 -0500 Sorry 150 metres. Wide fingers on keyboard... Bob Bob wrote: > The ground mat would > probably need to be at least 15 metres out from the antenna base. > Article: 218243 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: Message-ID: Date: Sat, 08 Oct 2005 00:25:46 GMT Owen Duffy wrote: > Cecil, do you have some quantitative explanation / support for this? Nope, but there were no disagreeing postings. > I am not asking whether or not field conditions (and V/I on the > conductors) immediate to the discontinuity are not Zo of either of the > lines, just where has the 2% of a wavelength come from? As I remember it came from the spacing between conductors Vs wavelength. The spacing between conductors is about 0.1 inches for RG-58. How many times that value would you think it would take for a transmission line to force its Z0 upon the signals? At 10 MHz, 2% of a wavelength (24 inches) is about 250 times the spacing between conductors. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218244 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: Message-ID: Date: Sat, 08 Oct 2005 00:33:32 GMT Reg Edwards wrote: > Only Cecil could dream up a use for such an effect. Sorry Reg, I only dream of six foot tall blonds with big boobs. The 2% WL value came from sci.physics.electromag. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218245 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: V/I ratio is forced to Z0 Date: Sat, 8 Oct 2005 01:01:49 +0000 (UTC) Message-ID: References: > > Only Cecil could dream up a use for such an effect. > > Sorry Reg, I only dream of six foot tall blonds with big boobs. > The 2% WL value came from sci.physics.electromag. ======================================== Yes Cec, you've told us before. I read the thread. That newsgroup has more highly-convincing old-wives than this one has. They are just a little harder to detect. 2% of wavelength is meaningless unless you also state by how much input impedance has diverged from Zo after a time T has elapsed. Wavelength also implies a frequency but what THAT has to do with it is anybody's guess. It merely adds to the confusion. ---- Reg, G4FGQ Article: 218246 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: V/I ratio is forced to Z0 Message-ID: <3j8ek1h0q4j5u2tfs1s3p19d6j4gioejrh@4ax.com> References: Date: Sat, 08 Oct 2005 02:13:25 GMT On Sat, 08 Oct 2005 00:25:46 GMT, Cecil Moore wrote: >Owen Duffy wrote: >> Cecil, do you have some quantitative explanation / support for this? > >Nope, but there were no disagreeing postings. > >> I am not asking whether or not field conditions (and V/I on the >> conductors) immediate to the discontinuity are not Zo of either of the >> lines, just where has the 2% of a wavelength come from? > >As I remember it came from the spacing between conductors Vs wavelength. >The spacing between conductors is about 0.1 inches for RG-58. How many >times that value would you think it would take for a transmission line >to force its Z0 upon the signals? At 10 MHz, 2% of a wavelength (24 inches) >is about 250 times the spacing between conductors. It seems different people have this conceptual model of "a transmission line forcing its Z0 upon the signals" in a gradual way, though differing propositions for the length of line that does not behave as predicted by Zo. An extension of that thinking is in the proposition that I have seen that a Bird 43 cannot give valid readings unless there is at least a quarter wave of 50 ohm line on each side of itself. In this case, the magnitude of significantly affected line seems to be 25%, someone else's is 2%, can they both be correct? It seems to me that apart from the region of the significant distortion of the fields local to some kind of discontinuity, that the fields further along the line at a distance from the discontinuity large compared to the dimension of the discontinuity (which will often be the conductor spacing) should be as constrained by the physical parameters of the line (V/I=Zo for each travelling wave). In the case of the Bird 43, I suggest that if had, say, at 1MHz, 75 ohm line and a 75 ohm load on the load side, that the V/I raio for the travelling waves in the region of the sampling element would be so close to 50 ohms as to not materially affect the accuracy of measurements on the 50 ohms coupler section, irrespective of the fact that the sampling element has only 0.02% of a wavelength of 50 ohm line on its load side. (For avoidance of doubt, nothing in the foregoing is to imply the Bird 43 would be directly measuring or indicating the conditions on the 75 ohm line.) Owen -- Article: 218247 of rec.radio.amateur.antenna From: Walter Maxwell Subject: Re: assymetrical antenna Message-ID: References: <9656-4346A412-598@storefull-3254.bay.webtv.net> Date: Fri, 07 Oct 2005 23:24:58 -0400 On Fri, 7 Oct 2005 11:36:34 -0500, richardharrison@webtv.net (Richard Harrison) wrote: >Myron Calhoun wrote: >"Wasn`t the design criteria something like "Make it 40 feet high, and >feed it 40 feet off center." > >The Windom was named for the amateur who described it in an article. It >was a 1/2-wavelengrh at its lowest frequency of use. A single feed wire >is connected at 0.34 X the length of the antenna, from one end. > >The Windom works best over highly conductive earth using a versatile >matching network to the transmitter. > >The 1/3 length feedpoint from one end is about 1/6 the distance from the >antenna`s centerpoint. 40 feet off center, makes the antenna 240 feet >long. This is 1/2-WL at 146 meters. It is 12 meters high. This is 1/4-WL >at 48 meters and >1/2-WL at 24 meters. > >Best regards, Richard Harrison, KB5WZI Although Loren Windom, W8ZG/W8GZ, wrote an article about the antenna for QST, he had nothing to do with its development, even though it has taken on his name. Loren was a student at Ohio State while Professors Everitt and Byrne were physics professors and Loren was one of their students. He trailed along with them during their experiments with the off-center fed dipole, wrote up the specifics, submitted his writing to QST, after which the hams started using that antenna. Because Windom's name was on the article as the author, the antenna became known as the Windom in ham circles. Walt, W2DU Article: 218248 of rec.radio.amateur.antenna From: "RST Engineering" Subject: Re: How to model on EZNEC Date: Fri, 7 Oct 2005 20:38:43 -0700 Message-ID: <11kefq8um53n22@corp.supernews.com> References: <9hh1f.9103$U51.3133@news-server.bigpond.net.au> In my humble opinion, EZNEC is a POS for anything other than a simple "wire antenna". Try to do a true ground plane with bent radials? Try to do a simple patch? Try to do a J? Try to do ANY configuration other than a wire dipole and the sucker chokes. Jim "David" wrote in message news:9hh1f.9103$U51.3133@news-server.bigpond.net.au... > Does anyone know how I can model a coaxial sleeve antenna > on EZNEC ? Article: 218249 of rec.radio.amateur.antenna From: David Subject: Re: How to model on EZNEC References: <9hh1f.9103$U51.3133@news-server.bigpond.net.au> <11kefq8um53n22@corp.supernews.com> Message-ID: Date: Sat, 08 Oct 2005 03:53:55 GMT Jim, What would be your alternate suggestion ? Thanks Regards David ERST Engineering wrote: > In my humble opinion, EZNEC is a POS for anything other than a simple "wire > antenna". Try to do a true ground plane with bent radials? Try to do a > simple patch? Try to do a J? Try to do ANY configuration other than a wire > dipole and the sucker chokes. > > Jim > > > > "David" wrote in message > news:9hh1f.9103$U51.3133@news-server.bigpond.net.au... > >>Does anyone know how I can model a coaxial sleeve antenna >>on EZNEC ? > > > Article: 218250 of rec.radio.amateur.antenna From: "Crazy George" References: <43422d26$1@news.wineasy.se> <4342fba9_3@news1.prserv.net> <43436b5d$1@news.wineasy.se> <74jA3LZkXuRDFw7g@g3ohx.demon.co.uk> Subject: Re: Connecting several bandpass filters. Date: Fri, 7 Oct 2005 22:58:16 -0500 Message-ID: <4347476c_3@news1.prserv.net> Well, you know, it depends...... Optimally, one would like to have separate, independent antennas for each channel, the way we constructed the first CATV head ends up in the hills of Pennsylvania in the 1950s. But, then Scientific Atlanta and others designed LPD antennas which covered multiple channels coming from one general direction, and since tower space and loading was always a concern (don't forget multiple runs of low loss coax enter that equation also), multiple antennas gave way to fewer antennas and lots of signal processing down at the base of the tower. Some sites had racks and racks of gear. If the requirement is to provide signals to only one TV, a switch could be a good choice. On the other hand, if the design is for a whole house, or apartment complex or commercial building signal distribution system, then it gets progressively more complicated. Since Svend didn't specify, one had to conclude that he had already considered and rejected the easy solutions. -- Crazy George "Ian Jackson" wrote in message news:74jA3LZkXuRDFw7g@g3ohx.demon.co.uk... > With all those channels mixed together, it would be best to simply use > an A/B switch to switch between the two antennas. > Ian. > > > In message <43436b5d$1@news.wineasy.se>, SH writes > >Thanks for both you answers its nice to now i stil remember some theory > >eventhough its 10 years since i read some UHF theory (Ended up being a > >programmer :-)))) > > > >I think ill go for the notch version. I have made a lot of them and they are > >easy to build but I've noticed that it seams that 3 notches (adjusted to 3 > >diff freq.) is some kind of limit. When i put in no. 4 it seams that the > >overall loss increases. > >Do I remember correctly when i state that 2 nothes on the same freq. should > >be a 1/4 wave apart??? > > > >Best regards > > > >Svend Holby > > > >"Crazy George" wrote in message > >news:4342fba9_3@news1.prserv.net... > >> Ben Jackson has some good points. You need not worry about audio, > >> usually, > >> as the FM capture takes care of the weaker signal. So, filtering the > >> video > >> carrier and near sidebands is all that is necessary. > >> > >> However, in answer to your question, the way you connect bandpass filters > >> in > >> parallel is with power dividers, amplifiers, and power dividers again, > >> backwards as summers. Otherwise, controlling the out of band input and > >> output impedances of several in parallel is a monumental, but solvable > >> task. > >> Spice, anyone? > >> > >> -- > >> Crazy George > >> "SH" wrote in message > >> news:43422d26$1@news.wineasy.se... > >>> Hi > >>> > >>> I have come up with one of those crazy DYI ideas which I would like to > >> try > >>> to implement but one thing still remains. > >>> > >>> I have two UHF (TV) arial pointing in different directions and would like > >> to > >>> connect them together through BP filters to minimize noise. > >>> BP = Bandpass > >>> Antenna 1: UHF channel (Europe) BP 1 ch 22-37, BP 2 ch40 -44, BP 3 ch > >>> 49 - > >>> 68/ or high pass > >>> Antenna 2: UHF channel (Europe) BP 1 ch 21 / or low pass, BP 2 ch38 -39, > >> BP > >>> 3 ch 47 > >>> > >>> I have found formulas to design each section of BF but how to you connect > >>> several BP filters in parallel??? I have investigated some old TV filter > >> and > >>> they have a coil (12 WDG) in and out of each BP section but is that the > >> way > >>> to do it and how does it influence the design of each BP. > >>> > >>> The only approach that I can find is to split the signal into three (- > >> 6dB ) > >>> then feed each into a BP filter and the Combine them again (-6dB). This > >> will > >>> result in each BP section seeing 75 Ohms as they shouland they would not > >>> interfere with eachother. Ofcouse i would need a 20 dB amplifier to fix > >> the > >>> loss. > >>> > >>> But is there a better way. > >>> > >>> Best regards > >>> > >>> Svend Holby > >>> > >>> > >> > >> > > > > > > -- > Article: 218251 of rec.radio.amateur.antenna From: David Subject: Suitable antenna for RF behind a vehicle Message-ID: Date: Sat, 08 Oct 2005 03:59:45 GMT I have an application that requires RF to be propagated for several hundred metres behind a vehicle at 433 MHz. I am looking for ideas for an antenna that could be built into the metal enclosure that houses the electronics. (ie. A single square or round enclosure). Ideally the field would fan out behind the vehicle and not have any side lobes. (Only want RF behind the vehicle). I am not worried about vertical propagation, Mainly just parallel to the ground about 1.5m. I am not sure if maybe I could get a corner reflector, patch antenna, PCB loop, parabola or slot antenna into a fairly small surface area (around 200mm x 200mm). The transmit power is 25mW. Any ideas much appreciated. Thanks Regards David Article: 218252 of rec.radio.amateur.antenna From: "Lee" Subject: Re Magnetic Loop !!! Message-ID: Date: Sat, 08 Oct 2005 06:26:31 GMT To continue the saga...... I fitted a variable capacitor to my 10 foot circumference 1mtr loop and am able to tune 80 to almost 15 meters...works well..but......... How to fit a motor drive !!!.....there seems to be nowhere to acquire cogs, pulleys or gear sets....no model shops around that carries components, that i`ve googled for anyway..(now when i were a lad! ).... ;-) Can you imagine how fast that electric motor turns the capacitor, even with reduced voltage???..you have to be quick i can tell you or you miss the sweet spot heh,heh.... Seriously, any ideas to slow the tuning rate will be most welcome . Thanks. Lee......G6ZSG..... Article: 218255 of rec.radio.amateur.antenna From: "Lee" References: Subject: Re: Re Magnetic Loop !!! Message-ID: Date: Sat, 08 Oct 2005 08:05:35 GMT "Richard Clark" wrote in message news:h4tek1tsolpiscp31rn844v6ijebdhaoda@4ax.com... > On Sat, 08 Oct 2005 06:26:31 GMT, "Lee" > wrote: > >Seriously, any ideas to slow the tuning rate will be most welcome . > > Hi Lee, > > Use the old stand-by of the screwdriver antennas, a screwdriver motor. Tried that, it has far to much torque even on low volts .... damaged the gearing on my spare cap :-/ > However, I expect you want two speed - then try a variable speed > battery powered drill. Good idea, worth looking into!! > For fine resolution and high speed both, look into the world of > Stepper motors. You can even design for calibrated settings instead > of hunting - or rough position indicators. I`ll do a google for steppermotors .... thanks. Lee.....G6ZSG.... > > 73's > Richard Clark, KB7QHC Article: 218256 of rec.radio.amateur.antenna From: Ian Jackson Subject: Re: Connecting several bandpass filters. Date: Sat, 8 Oct 2005 09:18:27 +0100 Message-ID: References: <43422d26$1@news.wineasy.se> <4342fba9_3@news1.prserv.net> Re-reading Svend's mail, he wants Channels 22 to 37, 40 to 44, and 49 to 64 (Antenna 1). He then needs to add Channel 21 and 38 + 39 (Antenna 2). This should not be too difficult. Obviously, the filters will not totally reject channels which are close (for example, the 22 to 37 filter will not reject 21 very well). There will be a certain amount of unwanted noise outside the passband of each filter, and ghosting (due to pick-up on the 'wrong' antenna) may not be totally eliminated. It may be necessary to fit one or two notch filters. I would first fit a level-raising amplifier to the feed from each antenna. There is nothing like having lots of signal level to play with! At the output of Amplifier 1, use a 4*-way CATV splitter to obtain four feeds. The loss will be about 8dB (for a splitter which uses ferrite transformers). Each output will be isolated from the others (typically by about 25dB). [*Note: 2, 4 and 8-way splitters are 'standard building blocks' in the world of cable TV. You can get 3-way and 6-way, but they are not easy to find). To three of the feeds, fit bandpass filter for Channels 22 to 37, 40 to 44 and 49 to 64. He can use the fourth output for monitoring. At the output of Amplifier 2, use another 4*-way CATV splitter to obtain 4 feeds. To two of the feeds, fit bandpass filter for Channels 21 and 38+39. He now has six separate TV feeds. If he wants, he can fit in-line variable attenuators to each to equalise the signal levels. The six TV feeds are then connected together using an 8*-way splitter (as a combiner) or two 4-ways then a 2-way. There should be little interaction between them. The loss will be about 11dB. Assuming a loss of 2dB for each filter, the total loss of this system will be 8 + 11 + 2 = 21dB. All that remains it to design (or obtain). 'normal' filters for each block of channels. There is a company in the UK which has a good range of equipment for MATV and CATV: http://www.taylorbros.co.uk I don't see anything there which is exactly what Svend wants, but here probably other companies in Europe which have can supply similar equipment. Ian. In message <4347476c_3@news1.prserv.net>, Crazy George writes >Well, you know, it depends...... > >Optimally, one would like to have separate, independent antennas for each >channel, the way we constructed the first CATV head ends up in the hills of >Pennsylvania in the 1950s. But, then Scientific Atlanta and others >designed LPD antennas which covered multiple channels coming from one >general direction, and since tower space and loading was always a concern >(don't forget multiple runs of low loss coax enter that equation also), >multiple antennas gave way to fewer antennas and lots of signal processing >down at the base of the tower. Some sites had racks and racks of gear. > >If the requirement is to provide signals to only one TV, a switch could be a >good choice. On the other hand, if the design is for a whole house, or >apartment complex or commercial building signal distribution system, then it >gets progressively more complicated. Since Svend didn't specify, one had to >conclude that he had already considered and rejected the easy solutions. >-- >Crazy George > >"Ian Jackson" wrote in message >news:74jA3LZkXuRDFw7g@g3ohx.demon.co.uk... >> With all those channels mixed together, it would be best to simply use >> an A/B switch to switch between the two antennas. >> Ian. >> >> >> In message <43436b5d$1@news.wineasy.se>, SH writes >> >Thanks for both you answers its nice to now i stil remember some theory >> >eventhough its 10 years since i read some UHF theory (Ended up being a >> >programmer :-)))) >> > >> >I think ill go for the notch version. I have made a lot of them and they >are >> >easy to build but I've noticed that it seams that 3 notches (adjusted to >3 >> >diff freq.) is some kind of limit. When i put in no. 4 it seams that the >> >overall loss increases. >> >Do I remember correctly when i state that 2 nothes on the same freq. >should >> >be a 1/4 wave apart??? >> > >> >Best regards >> > >> >Svend Holby >> > >> >"Crazy George" wrote in message >> >news:4342fba9_3@news1.prserv.net... >> >> Ben Jackson has some good points. You need not worry about audio, >> >> usually, >> >> as the FM capture takes care of the weaker signal. So, filtering the >> >> video >> >> carrier and near sidebands is all that is necessary. >> >> >> >> However, in answer to your question, the way you connect bandpass >filters >> >> in >> >> parallel is with power dividers, amplifiers, and power dividers again, >> >> backwards as summers. Otherwise, controlling the out of band input and >> >> output impedances of several in parallel is a monumental, but solvable >> >> task. >> >> Spice, anyone? >> >> >> >> -- >> >> Crazy George >> >> "SH" wrote in message >> >> news:43422d26$1@news.wineasy.se... >> >>> Hi >> >>> >> >>> I have come up with one of those crazy DYI ideas which I would like >to >> >> try >> >>> to implement but one thing still remains. >> >>> >> >>> I have two UHF (TV) arial pointing in different directions and would >like >> >> to >> >>> connect them together through BP filters to minimize noise. >> >>> BP = Bandpass >> >>> Antenna 1: UHF channel (Europe) BP 1 ch 22-37, BP 2 ch40 -44, BP 3 ch >> >>> 49 - >> >>> 68/ or high pass >> >>> Antenna 2: UHF channel (Europe) BP 1 ch 21 / or low pass, BP 2 >ch38 -39, >> >> BP >> >>> 3 ch 47 >> >>> >> >>> I have found formulas to design each section of BF but how to you >connect >> >>> several BP filters in parallel??? I have investigated some old TV >filter >> >> and >> >>> they have a coil (12 WDG) in and out of each BP section but is that >the >> >> way >> >>> to do it and how does it influence the design of each BP. >> >>> >> >>> The only approach that I can find is to split the signal into three (- >> >> 6dB ) >> >>> then feed each into a BP filter and the Combine them again (-6dB). >This >> >> will >> >>> result in each BP section seeing 75 Ohms as they shouland they would >not >> >>> interfere with eachother. Ofcouse i would need a 20 dB amplifier to >fix >> >> the >> >>> loss. >> >>> >> >>> But is there a better way. >> >>> >> >>> Best regards >> >>> >> >>> Svend Holby >> >>> >> >>> >> >> >> >> >> > >> > >> >> -- >> > > -- Article: 218257 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Re Magnetic Loop !!! Message-ID: References: Date: Sat, 08 Oct 2005 09:00:21 GMT On Sat, 08 Oct 2005 06:26:31 GMT, "Lee" wrote: >To continue the saga...... > >I fitted a variable capacitor to my 10 foot circumference 1mtr loop and am >able to tune 80 to almost 15 meters...works well..but......... > >How to fit a motor drive !!!.....there seems to be nowhere to acquire cogs, >pulleys or gear sets....no model shops around that carries components, that >i`ve googled for anyway..(now when i were a lad! ).... ;-) > >Can you imagine how fast that electric motor turns the capacitor, even with >reduced voltage???..you have to be quick i can tell you or you miss the >sweet spot heh,heh.... > >Seriously, any ideas to slow the tuning rate will be most welcome . Assuming it is a permag motor, reduce the motor voltage... add a current limited driver to limit the torque, an electronic shear pin if you like... except it doesn't shear. I am assuming that you are trying to tune the reactance out, to achieve an acceptable VSWR on the line to the ATU/transceiver. Have you considered automating the capacitor drive. You could build a phase detector (between V and I at the antenna input) as a sensor to control the motor drive. Owen -- Article: 218259 of rec.radio.amateur.antenna From: "Lee" References: <6kvek1lupr22cbig9mbd7fdbor8gmmbblh@4ax.com> Subject: Re: Re Magnetic Loop !!! Message-ID: Date: Sat, 08 Oct 2005 12:50:30 GMT "Richard Clark" wrote in message news:6kvek1lupr22cbig9mbd7fdbor8gmmbblh@4ax.com... > On Sat, 08 Oct 2005 08:05:35 GMT, "Lee" > wrote: > > >> Use the old stand-by of the screwdriver antennas, a screwdriver motor. > > > >Tried that, it has far to much torque even on low volts .... damaged the > >gearing on my spare cap :-/ > > Hi Lee, > > One way to control that, at least speed-wise, is to turn the DC > voltage into pulse-width modulated voltage. You are always applying > the same voltage, but you turn it on for a short-to-long time, and off > for a long-to-short time over any interval. You change the speed by > changing these times. This is more properly called Dwell Time. Yes, i`ve been looking into that and it seems the best way to go, a local supplier has a panel mount version in stock £15.00 ($16.00??)......so!!. > This offers the prospects of maintaining a constant torque over a > considerable range of speed. I'm not certain by what you mean about > "too much torque," unless you have too much resistance for the gears > to drive.... Not enough resistance, the capacitor comes to the end of its travel but the torque wants to continue..... hence the damage to my spare capacitor!!!. Regards. Lee...G6ZSG...... > 73's > Richard Clark, KB7QHC Article: 218260 of rec.radio.amateur.antenna From: "Lee" References: Subject: Re: Re Magnetic Loop !!! Message-ID: Date: Sat, 08 Oct 2005 12:53:11 GMT "Owen Duffy" wrote in message news:v92fk15p4e5sh59fo4mkvvi8287ko2an8d@4ax.com... > On Sat, 08 Oct 2005 06:26:31 GMT, "Lee" > wrote: > > >To continue the saga...... > > > >I fitted a variable capacitor to my 10 foot circumference 1mtr loop and am > >able to tune 80 to almost 15 meters...works well..but......... > > > >How to fit a motor drive !!!.....there seems to be nowhere to acquire cogs, > >pulleys or gear sets....no model shops around that carries components, that > >i`ve googled for anyway..(now when i were a lad! ).... ;-) > > > >Can you imagine how fast that electric motor turns the capacitor, even with > >reduced voltage???..you have to be quick i can tell you or you miss the > >sweet spot heh,heh.... > > > >Seriously, any ideas to slow the tuning rate will be most welcome . > > Assuming it is a permag motor, reduce the motor voltage... add a > current limited driver to limit the torque, an electronic shear pin if > you like... except it doesn't shear. > > I am assuming that you are trying to tune the reactance out, to > achieve an acceptable VSWR on the line to the ATU/transceiver. Have > you considered automating the capacitor drive. You could build a phase > detector (between V and I at the antenna input) as a sensor to control > the motor drive. Doesn`t work with a magloop!!!.....thanks anyway. Lee.....G6ZSG..... > > Owen > -- Article: 218261 of rec.radio.amateur.antenna From: "Lee" References: Subject: Re: Re Magnetic Loop !!! Message-ID: Date: Sat, 08 Oct 2005 12:58:53 GMT "Adelphia" wrote in message news:aOudna1Gt_eTM9reRVn-rg@adelphia.com... > Here in the USA ALL Electronics had 12volt 6RPM DC motors. I drive my large > 4600v variable with it using a DC pulse width motor speed control. The motor > control was around $22 as a kit in the USA. I would actually like about 3RPM > since the motor control slow speed needed for fine tuning is in a small > range. I could gear it but a mechanical mess. A simple DPDT switch is used > to reverse direction. > > Check your electronic parts dealers to see if they have motor with built-in > gear boxes. Best way to do it. Yes, thanks Lee....G6ZSG...... > > Dick N3HKN > PS: My loop is 1 meter on a side square and is used on 20 meters in the > attic. I have set it outside where the noise level is less but on really > cold days the motor will not turn. Used a simple plastic container from a > local discount store. I'll stick to the attic since I have a GAP vertical as > well. Yes, they are comparable given the dipole like pattern of the loop. > Article: 218262 of rec.radio.amateur.antenna From: "Lee" References: <6kvek1lupr22cbig9mbd7fdbor8gmmbblh@4ax.com> Subject: Re: Re Magnetic Loop !!! Message-ID: Date: Sat, 08 Oct 2005 13:20:17 GMT "Lee" wrote in message news:qgP1f.9203$tS4.3361@fe1.news.blueyonder.co.uk... > > "Richard Clark" wrote in message > news:6kvek1lupr22cbig9mbd7fdbor8gmmbblh@4ax.com... > > On Sat, 08 Oct 2005 08:05:35 GMT, "Lee" > > wrote: > > > > >> Use the old stand-by of the screwdriver antennas, a screwdriver motor. > > > > > >Tried that, it has far to much torque even on low volts .... damaged the > > >gearing on my spare cap :-/ > > > > Hi Lee, > > > > One way to control that, at least speed-wise, is to turn the DC > > voltage into pulse-width modulated voltage. You are always applying > > the same voltage, but you turn it on for a short-to-long time, and off > > for a long-to-short time over any interval. You change the speed by > > changing these times. This is more properly called Dwell Time. > > Yes, i`ve been looking into that and it seems the best way to go, a local > supplier has a panel mount version in stock £15.00 ($16.00??)......so!!. Typo ($26.00??)...... > > > This offers the prospects of maintaining a constant torque over a > > considerable range of speed. I'm not certain by what you mean about > > "too much torque," unless you have too much resistance for the gears > > to drive.... > > Not enough resistance, the capacitor comes to the end of its travel but the > torque wants to continue..... hence the damage to my spare capacitor!!!. > > Regards. > > Lee...G6ZSG...... > > > 73's > > Richard Clark, KB7QHC > > Article: 218263 of rec.radio.amateur.antenna From: Not Spam Subject: Re: www.liveboard.8my.com Date: Sat, 08 Oct 2005 15:27:16 +0000 Message-ID: References: <1128768422.972554.248230@o13g2000cwo.googlegroups.com> thegreat_lover2003 wrote: [Spam] > Note: This is not SPAM Fuck off and die. Note: This is not an insult. Article: 218264 of rec.radio.amateur.antenna From: "Frank" References: <9hh1f.9103$U51.3133@news-server.bigpond.net.au> Subject: Re: How to model on EZNEC Message-ID: Date: Sat, 08 Oct 2005 13:36:37 GMT "David" wrote in message news:9hh1f.9103$U51.3133@news-server.bigpond.net.au... > Does anyone know how I can model a coaxial sleeve antenna > on EZNEC ? > > I know how to enter a standard Vertical 1/2 wave but not sure how > to represent the coax going up through the tubing(sleeve) in the lower > portion. > > Thanks in advance. Just model a vertical dipole. The presence of a coaxial cable, within the lower conductor, will not effect its performance. For your model both upper and lower conductors should be the same diameter. Dissimilar diameters in a model can produce erroneous results. NEC has its limitations, but alternative, FEM based, programs can cost tens of thousands of dollars. Regards, Frank Article: 218265 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Re Magnetic Loop !!! References: Message-ID: Date: Sat, 08 Oct 2005 13:54:14 GMT Lee wrote: > Seriously, any ideas to slow the tuning rate will be most welcome . What's wrong with a gear-head motor? I have some in my junk box. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218266 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: Message-ID: <9iQ1f.9878$oO2.3813@newssvr27.news.prodigy.net> Date: Sat, 08 Oct 2005 14:00:37 GMT Dave wrote: >>The 2% WL value came from sci.physics.electromag. > then please take it back there. it makes no sense as it would force the > effect to get longer and longer at lower frequencies. So how long does the coax have to be to force V/I to Z0 when the applied signal is DC? -- 73, Cecil http://www.qsl.net/w5dxp Article: 218267 of rec.radio.amateur.antenna From: "Ralph Mowery" Subject: safety/working harness Message-ID: <4pQ1f.11362$QE1.6241@newsread2.news.atl.earthlink.net> Date: Sat, 08 Oct 2005 14:08:00 GMT Planning on putting up my own tower and I need a safety harness/working belt of my own. I have used some on other projects so I have an idea of what I want, just need a few web sights/brand names to look for. I don't need a super heavy duty one to work in all day,every day, but one to use two or three times a year. Article: 218268 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: How to model on EZNEC References: <9hh1f.9103$U51.3133@news-server.bigpond.net.au> <11kefq8um53n22@corp.supernews.com> Message-ID: Date: Sat, 08 Oct 2005 14:08:19 GMT RST Engineering wrote: > In my humble opinion, EZNEC is a POS for anything other than a simple "wire > antenna". Try to do a true ground plane with bent radials? Try to do a > simple patch? Try to do a J? Try to do ANY configuration other than a wire > dipole and the sucker chokes. I've modeled ground planes with bent radials and J antennas using EZNEC and got reasonable results. Never tried a patch. EZNEC's limitations are well known and well documented so knowledgeable users can avoid those pitfalls. Of course, nothing is foolproof. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218269 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: <3j8ek1h0q4j5u2tfs1s3p19d6j4gioejrh@4ax.com> Message-ID: Date: Sat, 08 Oct 2005 14:13:02 GMT Owen Duffy wrote: > An extension of that thinking is in the proposition that I have seen > that a Bird 43 cannot give valid readings unless there is at least a > quarter wave of 50 ohm line on each side of itself. In this case, the > magnitude of significantly affected line seems to be 25%, someone > else's is 2%, can they both be correct? I think if you will recheck that posting you will find the assertion was that a Bird 43 cannot give valid readings by sampling at a point. The line must be at least 1/4WL, and preferably 1/2WL, so that voltage maximums and minimums will exist and can be measured. And that 2% of a wavelength is from my faulty memory. I'll try to Google and find the exact quotation. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218270 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Re Magnetic Loop !!! References: Message-ID: Date: Sat, 08 Oct 2005 14:18:59 GMT Lee wrote: > Seriously, any ideas to slow the tuning rate will be most welcome . The latest QST has a 6 RPM 12v gearhead motor from All Electronics advertised on page 161 for $13.75. Runs 3 RPM at 6v. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218271 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: <9iQ1f.9878$oO2.3813@newssvr27.news.prodigy.net> Message-ID: Date: Sat, 08 Oct 2005 15:00:54 GMT Dave wrote: > just enough for any fringe effects to become negligible... no more than a > couple diameters of the coax as a rough guess. Apparently, the 2% of a wavelength that I was remembering was at 10 MHz. 1'/(98.4*0.66) rounded to 2%. All I was interested in at the time was proving to Reg that one foot of coax forces Vfor/Ifor = Vref/Iref = Z0, the boundary conditions assumed by Bird Wattmeter designers. Since Kevin was not familiar with PL-239's, I erred on the side of caution with the 2% estimate. ****Quote**** Newsgroups: sci.physics.electromag From: "Kevin G. Rhoads" Date: Tue, 07 Oct 2003 12:49:14 -0400 Subject: Re: Transmission Line Question Cecil wrote: >It addresses it adequately but doesn't answer any particulars. >Given PL-239 connectors and RG-213 coax, I wonder what the >answer would be for 10 MHz? I'm not familiar with the connectors in question. Assuming they are properly attached, they should not introduce much mode diversion. For 10 MHz I would expect that all other modes would be non-propagating (i.e., evanescent) even though RG-213 is a large coax (improved RG-8 apparently). The speed of propagation is listed as 66%, so the nominal wavelength is 3/2 times the free space wavelength for the TEM mode. 3/2 x 30m = 45m, which implies the decay rate in space for non-TEM modes is going to be large as the cable diameter is .405" (jacket) which implies the spacing from inner to outer conductors will be less than .203". For order of magnitude estimate, assuming the lowest non-TEM mode can be approximated using a characteristic equation that really is only applicable in Cartesian geometries: (1/45m)**2 = (1/.203")**2 + kz**2 Clearly, kz must be imaginary to make this work. thus an evanescant, non-propagating wave: kz**2 = (1/45m)**2 - (1/.203")**2 To the accuracy used to date, the first term on the right is negligible, so the decay rate, alpha, can be estimated: alpha**2 = - (kz)**2 = (1/2.03")**2 Or, the lowest order undesired mode should reduce intensity by a factor of 1/e (0.37) in about 2.03"; power will reduce by that factor squared in the same distance (.135). In about four inches, undesired mode power is down to about 0.018, in six inches, .00248, and after a foot, 6.14x10-6 You should double check my algebra, but I think the estimate is reasonable. To put it into other terms, since the wavelength in the coax dielectric is 45m and the conductor to conductor spacing is about 2", any non-TEM mode will suffer attenuation in E-field intensity with a space-rate constant rounghly equal to the conductor to conductor spacing. INtensity drops by 1/e = 1/2.71828 every 2 inches. Power availalbe drops faster, being square of intensity. So unless almost all the power diverts into an undesireable mode (by a factor of more than a million to one), one foot of cable should see pure TEM at the end. HTH Kevin ****End Quote**** -- 73, Cecil http://www.qsl.net/w5dxp Article: 218272 of rec.radio.amateur.antenna From: Bob Miller Subject: Re: safety/working harness Message-ID: References: <4pQ1f.11362$QE1.6241@newsread2.news.atl.earthlink.net> Date: Sat, 08 Oct 2005 15:01:34 GMT On Sat, 08 Oct 2005 14:08:00 GMT, "Ralph Mowery" wrote: >Planning on putting up my own tower and I need a safety harness/working belt >of my own. I have used some on other projects so I have an idea of what I >want, just need a few web sights/brand names to look for. I don't need a >super heavy duty one to work in all day,every day, but one to use two or >three times a year. > the Texas Towers website had some safety gear, last time I looked bob k5qwg Article: 218273 of rec.radio.amateur.antenna From: "Ralph Mowery" References: <4pQ1f.11362$QE1.6241@newsread2.news.atl.earthlink.net> <5flfk150cu6njucf4amno77qqvrunjrcdr@4ax.com> Subject: Re: safety/working harness Message-ID: Date: Sat, 08 Oct 2005 15:31:51 GMT > >want, just need a few web sights/brand names to look for. I don't need a > >super heavy duty one to work in all day,every day, but one to use two or > >three times a year. > > Because your life is going to depend on this, why would you skimp on > it? > > Mine is a Miller with chest, back and waist D-rings. Something like > this: > > http://www.grainger.com/Grainger/productdetail.jsp?xi=xi&ItemId=1611763453&ccitem= > Thanks for the URL. I did not mean I wanted to skimp on the quality or safety. I spent about half a day several years ago in a demonstration at work on safety harnesses. They were for fall protection only and not for working in where you want support and both hands free like you would on a tower. I just ment that I will only use it for a short period of time and not very many times per year. What I would be skimping on would be heavy padding and comfort. Sort of like you can sit on a wooden chair for a short period of time but if you had to sit all day every day you would want to spend lots more and get a good padded chair. Article: 218274 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: Re Magnetic Loop !!! References: Message-ID: <634l13-k0t.ln1@p400bob.personal.cox.net> Date: Sat, 08 Oct 2005 10:09:58 -0500 Hi Lee Two thoughts Re stepper motors. You can often find them in old junked scanners. A nice cheap source. If you are feeling really cheap the interface can intially be a simple TTL counter cct and some pass transistors. I once used one off my PC parallel port for an EzAl antenna system. Also look at the possibility of using a piston capacitor and driving that with a threaded bar connected to your motor. This may still be a little fast though. You might also get away with a long lever and threaded bar arrangement if turning a standard rotary capacitor. Kind of limits you to something less than 180 degrees tho. A car windscreen wiper motor is another possibility also through a threaded bar. (Overkill on the torque tho) Cheers Bob Vk2YQA Lee wrote: > "Richard Clark" wrote in message > news:h4tek1tsolpiscp31rn844v6ijebdhaoda@4ax.com... > >>On Sat, 08 Oct 2005 06:26:31 GMT, "Lee" >>wrote: >> >>>Seriously, any ideas to slow the tuning rate will be most welcome . Article: 218275 of rec.radio.amateur.antenna From: "Frank" References: <9hh1f.9103$U51.3133@news-server.bigpond.net.au> Subject: Re: How to model on EZNEC Message-ID: Date: Sat, 08 Oct 2005 16:31:17 GMT >>Just model a vertical dipole. The presence of a coaxial cable, within the >>lower conductor, will not effect its performance. > > But the presence of the coax below the antenna sure will. As an experiment I modeled a #14 AWG, 133 segment,134 ft free space dipole. The input impedance at 3.575 MHz is 74.01 - j 0.749 ohms. Adding an additional 25 ft wire at one end -- ends separated by 1.2" -- the input impedance becomes 74.155 - j1.97 ohms. There is no discernable effect on the radiation pattern. While this test is not precisely equivalent; the presence of a, non connected, axial extension appears to have only a minimal effect on the antenna parameters. Regards, Frank Article: 218276 of rec.radio.amateur.antenna From: "Frank" References: <9hh1f.9103$U51.3133@news-server.bigpond.net.au> <7etfk1lpvpspfgi7u6vd8u0bm4kc463i44@4ax.com> Subject: Re: How to model on EZNEC Message-ID: Date: Sat, 08 Oct 2005 16:45:24 GMT "Richard Clark" wrote in message news:7etfk1lpvpspfgi7u6vd8u0bm4kc463i44@4ax.com... > On Sat, 08 Oct 2005 16:31:17 GMT, "Frank" > wrote: > >>While this test is not precisely equivalent; the presence of a, non >>connected, axial extension appears to have only a minimal effect on the >>antenna parameters. > > Hi Frank, > > And did resonance go unperturbed? > > 73's > Richard Clark, KB7QHC Hi Richard, A nominal 2.5 kHz shift, at 3.575 MHz (0.07%), is about all I can detect. 73, Frank Article: 218277 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: Suitable antenna for RF behind a vehicle References: Message-ID: Date: Sat, 08 Oct 2005 11:31:47 -0500 Hi David There are lots of possibilities here. Generally speaking though confining the antenna to a metal enclosure of 200mm x 200mm is going to severely impact its efficiency. I'd suggest that if you really want to use this size constraint make part of it out of something transparent to the signal (eg plastic/fibreglass) My first thought (and there are bound to be many more) is to setup a single full wave circular loop fed through a 1/4 wavelength balun such that the shield on the opposite side of the loop from the feedpoint is "grounded" there. Then mount it in front of a metal plate of gauze inside the plastic thing that contains it. If it is a square shaped box make it a square full wave (quad) shape. For horiz polarization the antenna would be fed at top or bottom of loop. Assuming the TX/RX device needs a 50 ohm antenna you can then adjust the loop to plate/gauze distance to get the best match or received field strength. You could of course mount the antenna off the metal box face some, and maybe use plastic of the same metal box dimensions if it is important to keep it enclosed. My gut feel for approximate dimensions are as follows; Antenna to metal plate/gauze - 50-100mm Antenna diameter (if circular) - 200-240 mm Antenna side length (if square) - 170-190 mm This antenna would probably give you a large single horiz lobe in the vicinty of 120 degrees half power beamwidth. This vertical pattern will of course be affected by the nearby ground and much of our radiation will be angled upwards and broken into a few lobes. If the 200mm is a hard dimension number I'd suggest you consider lightly loading the loop with some inductance to make it smaller. This will of course impact performance. I still maintain though that it should be mounted clear of the metal box in plastic or air. Keep in mind that at 433MHz there is going to be a lot of multipathing and the phase cancellations may be an issue if the distance becomes too great. I havent bothred to figure the path loss for the circuit you have described. It might be worth doing so to make sure its doable. Another consideration is do you expect it to work over the several hundred metres if there is a hill in the way? Hope you find this useful. Cheers Bob VK2YQA David wrote: > > > I have an application that requires RF to be propagated for several > hundred metres behind a vehicle at 433 MHz. > > Any ideas much appreciated. Article: 218278 of rec.radio.amateur.antenna From: microwaves@blueyonder.co.uk (Peter) Subject: Re: Aluminum tubing? Message-ID: <4348f9f7.286775451@news.blueyonder.co.uk> References: <1128562179_21@isp.n> Date: Sat, 08 Oct 2005 17:21:05 GMT On Wed, 05 Oct 2005 20:27:02 -0500, Allan Butler wrote: > I have tried all the local metal suppliers and several in the Chicago >area to get 6061-T6 aluminum tubing from in very specific sizes. I need to ^^^^^^^^ Why do you guys in the US always omit the "i" in aluminium ? Alsao why a car tire instead of tyre? Just asking ;-) Peter, G3PHO Article: 218279 of rec.radio.amateur.antenna From: "John N9JG" Subject: Re: Aluminum tubing? Date: Sat, 8 Oct 2005 12:53:00 -0500 Message-ID: References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> Also, why do we say tube rather than valve? "Peter" wrote in message news:4348f9f7.286775451@news.blueyonder.co.uk... > On Wed, 05 Oct 2005 20:27:02 -0500, Allan Butler > wrote: > >> I have tried all the local metal suppliers and several in the >> Chicago >>area to get 6061-T6 aluminum tubing from in very specific sizes. I need >>to > ^^^^^^^^ > > Why do you guys in the US always omit the "i" in aluminium ? > > Alsao why a car tire instead of tyre? > > Just asking ;-) > > > Peter, G3PHO Article: 218280 of rec.radio.amateur.antenna From: "John N9JG" Subject: Re: Re Magnetic Loop !!! Date: Sat, 8 Oct 2005 13:03:25 -0500 Message-ID: References: <634l13-k0t.ln1@p400bob.personal.cox.net> For a stepper motor check http://www.herbach.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=HAR&Product_Code=H2-553 and for the controller check http://www.alliedelec.com/Search/ProductDetail.asp?SKU=316-0061 "Bob Bob" wrote in message news:634l13-k0t.ln1@p400bob.personal.cox.net... > Hi Lee > > Two thoughts > > Re stepper motors. You can often find them in old junked scanners. A nice > cheap source. If you are feeling really cheap the interface can intially > be a simple TTL counter cct and some pass transistors. I once used one off > my PC parallel port for an EzAl antenna system. > > Also look at the possibility of using a piston capacitor and driving that > with a threaded bar connected to your motor. This may still be a little > fast though. You might also get away with a long lever and threaded bar > arrangement if turning a standard rotary capacitor. Kind of limits you to > something less than 180 degrees tho. > > A car windscreen wiper motor is another possibility also through a > threaded bar. (Overkill on the torque tho) > > Cheers Bob Vk2YQA > > Lee wrote: >> "Richard Clark" wrote in message >> news:h4tek1tsolpiscp31rn844v6ijebdhaoda@4ax.com... >> >>>On Sat, 08 Oct 2005 06:26:31 GMT, "Lee" >>>wrote: >>> >>>>Seriously, any ideas to slow the tuning rate will be most welcome . Article: 218281 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Transmitter ALC Date: Sat, 8 Oct 2005 18:54:44 +0000 (UTC) Message-ID: Automatic Level Control, ALC. What characteristics of the load impedance are used to automatically control the drive-level of the power amplifier? Whatever they are must apply to CW, SSB and FM modes of operation. ---- Reg. Article: 218282 of rec.radio.amateur.antenna From: "Phil" References: <4pQ1f.11362$QE1.6241@newsread2.news.atl.earthlink.net> Subject: Re: safety/working harness Message-ID: Date: Sat, 08 Oct 2005 18:56:48 GMT "Ralph Mowery" wrote in message news:4pQ1f.11362$QE1.6241@newsread2.news.atl.earthlink.net... > Planning on putting up my own tower and I need a safety harness/working > belt > of my own. I have used some on other projects so I have an idea of what > I > want, just need a few web sights/brand names to look for. I don't need a > super heavy duty one to work in all day,every day, but one to use two or > three times a year. > > Some utility workers use gear from PETZL. As far as I know, you can buy it in any REI. Article: 218283 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Aluminum tubing? References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> Message-ID: Date: Sat, 08 Oct 2005 20:24:09 GMT Peter wrote: > Also why a car tire instead of tyre? Why do your cars have bonnets even when it isn't Easter? -- 73, Cecil http://www.qsl.net/w5dxp Article: 218284 of rec.radio.amateur.antenna From: Russ Subject: Re: Aluminum tubing? Message-ID: References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> Date: Sat, 08 Oct 2005 19:58:10 GMT On Sat, 08 Oct 2005 17:21:05 GMT, microwaves@blueyonder.co.uk (Peter) wrote: >On Wed, 05 Oct 2005 20:27:02 -0500, Allan Butler >wrote: > >> I have tried all the local metal suppliers and several in the Chicago >>area to get 6061-T6 aluminum tubing from in very specific sizes. I need to > ^^^^^^^^ > > Why do you guys in the US always omit the "i" in aluminium ? > >Alsao why a car tire instead of tyre? > >Just asking ;-) > > >Peter, G3PHO Because "the English and the Americans are two peoples separated by a common language". G. B. Shaw, I believe. R Article: 218285 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: Aluminum tubing? References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> Message-ID: Date: Sat, 08 Oct 2005 14:43:58 -0500 And being even further OT Brings further ambiguity to the term "retired" as well. (Like my 65 yo father just had a wheel transplant) Since I live in W5... How does one say/spell Titanium/Titanum? I look at signs on the side of the road "Hiway" and cant for the life of me work out what that means... Peter, its actually said in the US how it looks. This gets real confusing for me! (Along with driving on the WRONG side of the road! ) Cheers Bob W5/VK2YQA East Texas (past the langauge test - can say "Y'all" easily) John N9JG wrote: >>Why do you guys in the US always omit the "i" in aluminium ? >> >>Alsao why a car tire instead of tyre? >> >>Just asking ;-) >> >> >>Peter, G3PHO > > > Article: 218286 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: V/I ratio is forced to Z0 Message-ID: <0r9gk11edov68vqjonkhmrg7h2c2a1kh6c@4ax.com> References: <3j8ek1h0q4j5u2tfs1s3p19d6j4gioejrh@4ax.com> Date: Sat, 08 Oct 2005 20:18:05 GMT On Sat, 08 Oct 2005 14:13:02 GMT, Cecil Moore wrote: >Owen Duffy wrote: >> An extension of that thinking is in the proposition that I have seen >> that a Bird 43 cannot give valid readings unless there is at least a >> quarter wave of 50 ohm line on each side of itself. In this case, the >> magnitude of significantly affected line seems to be 25%, someone >> else's is 2%, can they both be correct? > >I think if you will recheck that posting you will find the assertion Cecil, it is someone else who has on a number of occasions suggested the quarter wave thing in email correspondence, and here in postings. My suggestion is that the sampler inside a Bird 43 coupler section is sufficiently far inside the 50 ohm coupler line to provide measurements within the instrument's stated accuracy of what is happening within the 50 ohm coupler, irrespective of whether, for instance, a 75 ohm line is attached to the coupler on the load side. The measurements of what is happening within the Bird 43 coupler could then be used to model what is happening on the adjacent line, having regard for any Zo changes, loss, length etc. Owen -- Article: 218287 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: <3j8ek1h0q4j5u2tfs1s3p19d6j4gioejrh@4ax.com> <0r9gk11edov68vqjonkhmrg7h2c2a1kh6c@4ax.com> Message-ID: Date: Sat, 08 Oct 2005 20:33:14 GMT Owen Duffy wrote: > Cecil, it is someone else who has on a number of occasions suggested > the quarter wave thing in email correspondence, and here in postings? Yep, it's not me, it's Reg. I have defended the Bird wattmeter design. Reg sez one needs at least 1/4WL and preferably 1/2WL in order to accurately ascertain the "real" SWR. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218288 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: safety/working harness Message-ID: <63dgk11oesp15esv7h1a7dm1qkmd8iu809@4ax.com> References: <4pQ1f.11362$QE1.6241@newsread2.news.atl.earthlink.net> Date: Sat, 08 Oct 2005 21:15:08 GMT On Sat, 08 Oct 2005 14:08:00 GMT, "Ralph Mowery" wrote: >Planning on putting up my own tower and I need a safety harness/working belt >of my own. I have used some on other projects so I have an idea of what I >want, just need a few web sights/brand names to look for. I don't need a >super heavy duty one to work in all day,every day, but one to use two or >three times a year. > Will you be working alone? Who might rescue you, and how long might it take? If you plan on "hanging around", plan to be comfortable. Adequate width of leg straps in case you are sitting for a bit, clearance for the family jewels (assuming you are male, adequate width in the back to be comfortable leaning back on a pole strap. In my experience, lightweight harness are strong enough for the job, they just aren't comfortable. They are for fall arresting, instant rescue. What is suitable for hauling a plumber out of a sewer might not be comfortable on a tower for hours (even once a year). For pole straps, my preference is for adjustable ones that allow you to set a convenient position for working to minimise fatigue from using an arm to hang on. Pole straps are not fall arrestors, if you want a fall arrestor, you also need something like a shock absorbing lanyard. Owen -- Article: 218289 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: V/I ratio is forced to Z0 Message-ID: References: <3j8ek1h0q4j5u2tfs1s3p19d6j4gioejrh@4ax.com> <0r9gk11edov68vqjonkhmrg7h2c2a1kh6c@4ax.com> Date: Sat, 08 Oct 2005 21:22:32 GMT On Sat, 08 Oct 2005 20:33:14 GMT, Cecil Moore wrote: >Owen Duffy wrote: >> Cecil, it is someone else who has on a number of occasions suggested >> the quarter wave thing in email correspondence, and here in postings? > >Yep, it's not me, it's Reg. I have defended the Bird wattmeter >design. Reg sez one needs at least 1/4WL and preferably 1/2WL >in order to accurately ascertain the "real" SWR. Not it was not Reg... end of the guessing game. Having regard to the definition of VSWR (SWR), I can understand Reg's point that the direct way to measure VSWR requires sampling voltage or current over a quarter wave of line where you can find / observe the actual minimum and maximum. Having said that, there are other measurements that one can make that allow one to reasonably predict what the VSWR would be. Owen -- Article: 218290 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Re Magnetic Loop !!! Message-ID: References: Date: Sat, 08 Oct 2005 21:28:20 GMT On Sat, 08 Oct 2005 12:53:11 GMT, "Lee" wrote: > >Doesn`t work with a magloop!!!.....thanks anyway. Why is that? Owen -- Article: 218291 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Re Magnetic Loop !!! Date: Sat, 8 Oct 2005 21:36:59 +0000 (UTC) Message-ID: References: "Owen Duffy" wrote in message news:ieegk15h4qanu1m7t8nu15hb45erg6vvc4@4ax.com... > On Sat, 08 Oct 2005 12:53:11 GMT, "Lee" > wrote: > > > > >Doesn`t work with a magloop!!!.....thanks anyway. > > Why is that? > > Owen ========================== Because there is only one phase - that which corresponds to the motor driving voltage. ---- Reg. Article: 218292 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: Aluminum tubing? References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> Message-ID: <7irl13-0nt.ln1@p400bob.personal.cox.net> Date: Sat, 08 Oct 2005 16:50:30 -0500 Same argument I guess for having a hood like what an executioner wears! And what about the tree sans leaves, roots and branches in the rear of the car? We could no doubt go on forever. I maintain though that it doesn't matter how bad you spell, use colloquial terms or different languages. What matters is that we allow for ambiguous meaning and then dialogue to rectify misunderstanding.. It is a lot of fun though! Bob Cecil Moore wrote: > > Why do your cars have bonnets even when it > isn't Easter? Article: 218293 of rec.radio.amateur.antenna From: "Fred W4JLE" References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> Subject: Re: Aluminum tubing? Date: Sat, 8 Oct 2005 18:11:27 -0400 Message-ID: <71489$4348444b$97d558d8$4747@ALLTEL.NET> I guess it is because you folks just don't understand English. We also note you misspell color as well. "Peter" wrote in message news:4348f9f7.286775451@news.blueyonder.co.uk... > On Wed, 05 Oct 2005 20:27:02 -0500, Allan Butler > wrote: > > > I have tried all the local metal suppliers and several in the Chicago > >area to get 6061-T6 aluminum tubing from in very specific sizes. I need to > ^^^^^^^^ > > Why do you guys in the US always omit the "i" in aluminium ? > > Alsao why a car tire instead of tyre? > > Just asking ;-) > > > Peter, G3PHO Article: 218294 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Re Magnetic Loop !!! Message-ID: References: Date: Sat, 08 Oct 2005 22:16:24 GMT On Sat, 8 Oct 2005 21:36:59 +0000 (UTC), "Reg Edwards" wrote: > >"Owen Duffy" wrote in message >news:ieegk15h4qanu1m7t8nu15hb45erg6vvc4@4ax.com... >> On Sat, 08 Oct 2005 12:53:11 GMT, "Lee" > >> wrote: >> >> > >> >Doesn`t work with a magloop!!!.....thanks anyway. >> >> Why is that? >> >> Owen > >========================== >Because there is only one phase - that which corresponds to the motor >driving voltage. Call me thick, I still don't understand why you can't sample the RF V and I and feed them to a phase detector to provide an indication of whether to adjust the capacitor up or down to achieve resonance (V in phase with I). Owen -- Article: 218295 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Transmitter ALC Message-ID: <6shgk11bict76alt5j6gr0d0trekiu2gal@4ax.com> References: Date: Sat, 08 Oct 2005 22:39:11 GMT On Sat, 8 Oct 2005 18:54:44 +0000 (UTC), "Reg Edwards" wrote: > >Automatic Level Control, ALC. > >What characteristics of the load impedance are used to automatically >control the drive-level of the power amplifier? Well, as you no doubt know Reg, in the early days of application of ALC to amateur transmitters it was literally to control the drive level of the PA, and often did that is a closed loop where excess drive in a class AB1 PA was detected by occurrence of grid current, which was used to reduce gain in prior stages to limit the drive level to AB1 conditions. Such a control system is indirectly affected by the PA load. Today, modern transceivers have further developed that idea to controlling the RF output voltage or (differently) PEP power out (ie be detecting Vout or power out and adjusting gain in prior stages to limit output. This might more loosely be called Automatic Power Control. In this case, the measurement point of the control loop is more directly affected by the load. Many modern solid state transceivers also detect poor loading using a reflectometer calibrated for the specified load for rated output power, and reduce drive based on the measured "reflected power" in the reflectometer to protect the PA (if that needs to be done anymore for that purpose - transistors are more robust). This might be properly described as PA Protection. The measurement is directly affected by the load, and is highly responsive to load changes beyond a configured threshold. All of these things may be included in the readers understanding of ALC. Certainly, many if not most, modern solid state transceivers perform all three of these functions, and display the control voltage as "ALC". And many current model external valve based high power PAs (Linear Amplifiers) still use the grid current detection scheme (if it is hooked back to the transceiver). > >Whatever they are must apply to CW, SSB and FM modes of operation. And AM? Owen >---- >Reg. > -- Article: 218296 of rec.radio.amateur.antenna From: "David Thompson" References: Subject: Re: US Tower TX-472 Base question Message-ID: <61Y1f.11967$q1.6140@newsread3.news.atl.earthlink.net> Date: Sat, 08 Oct 2005 22:48:34 GMT Either will worK OK. The main point is to get the three base pins in the correct position and vertical. The original TX-472 came with a plywood template with a hole for each pin. Place that on the wood surrounding the hole. My last hole was close to 4 X 4 X 7. If you don't have the 36 inch base pins with the bottom in a L (total length is 42") you have two choices. You can get a new set from US Tower (try to het HRO to order for you) or get 1" galvanized universal bolt (probably have to order from a hardware store or Mcmaster-carr) and have the bottom 6" bent at a right angle. I have moved my tower 4 times and have had good luck with the universal bolt. 73 Dave K4JRB "Sluggo" wrote in message news:rk59k1tcgu4p2kctj5h4khr706lb5q59nt@4ax.com... > I've got a TX-472; the problem is that at this QTH there is a > limestone hardpan at about 5' depth. The original engineering > drawing calls for a base of 4X4X7' deep. The latest drawing, > available in .pdf form from their website, now calls for > 5X5X6.5'. > > I'm hoping somebody here has run into a similar problem > and can provide dimensions; UST says their engineer > can draw it up, but for $300 or so. Needless to say, cheaper > or preferably is always better. I can afford to send 'em > the $ < I bought the tower used, it's not like they "owe" me>, > but if I *have to* spend the bucks, I might be inclined to > see if a local PE with the appropriate skills could do it, > just in case there ever were an issue with permitting, etc., > although I definately don't think that will happen, no permits > req'd in this county for amateur towers below 200' at this time. > > Thanks for any help you can offer. > > 73, > Sluggo > > (the email address in the headers is bogus, email to > jrandy AT usa DOt Com if necessary) Article: 218297 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Re Magnetic Loop !!! Date: Sun, 9 Oct 2005 01:31:54 +0000 (UTC) Message-ID: References: > > >Doesn`t work with a magloop!!!.....thanks anyway. > > > > Why is that? > > ========================== > Because there is only one phase - that which corresponds to the motor > driving voltage. > ---- > Reg. > ====================================== Automatic Antenna Tuners and Magloops. All ATUs work on the principle of adjusting tuning components such that the load presented to the transmitter has a reflection coefficient of RC = 0+j0 ohms. When mismatched the RC has both magnitude and phase. So there must be two L and/or C variables. That's why there are always at least two knobs on the front of a manual tuner. Or, when automatic, two electric motors. Or a set of relays which accomplish the same tasks. In the case of a T-network the variable components are usually a pair of reversible motor-driven capacitors. There is always a reflexion coefficient bridge which is at balance when the transmitter load is simultaneously R = 50 and jX = 0. Or impedance Magnitude = 50 and Phase = zero. The RC bridge circuit is similar to the so-called SWR bridge except that there are TWO voltage outputs - proportional to magnitude and phase of the RC. Output voltages are amplified to drive the reversible capacitor motors or operate the set of relays. The motors go backwards and forwards and react with each other similar to what a human operator does. When Z Magnitude = 50 and Phase Angle = zero, or sufficiently near, motors stop and the green LED comes on. Now, in the case of a magloop there is only one variable - the tuning capacitor. The other component involved with the tune-up process is FIXED. It is the diameter of the small coupling loop inside the main loop which is fixed. The small coupling loop, in conjunction with the main loop, behaves as the single-turn primary winding of an impedance matching transformer. The main loop, when at resonance, has a very low purely resistive impedance, the sum of the radiation and loss resistances. The effective turns-ratio of the transformer is approximately proportional to the ratio of the areas enclosed by the two loops. It so happens that when the diameter of the coupling loop is approx 1/5th of the main loop diameter, the impedance looking into the coupling loop is 50 ohms. If a 75-ohm feedline is used then the coupling loop needs to be a little larger. A nice property of a magloop is that an impedance match is approximately independent of frequency. When changing bands it is not necessary to change the diameter of the coupling loop even if could easily be adjusted. It can now be seen why the conventional ATU cannot be used with magloops. What is needed is something which searches for minimum loop impedance, or zero phase angle, as the tuning capacitor is varied. It then stops. Any ideas? ---- Reg, G4FGQ Article: 218298 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Re Magnetic Loop !!! Message-ID: <0ptgk19booqq7eqjkgkq567klgke1cajtk@4ax.com> References: Date: Sun, 09 Oct 2005 01:52:45 GMT On Sun, 9 Oct 2005 01:31:54 +0000 (UTC), "Reg Edwards" wrote: >magloops. What is needed is something which searches for minimum loop >impedance, or zero phase angle, as the tuning capacitor is varied. It >then stops. > >Any ideas? >---- >Reg, G4FGQ Isn't that what I described, a control system that samples RF V and I at the antenna end of the transmission line, and uses that to control the direction of the capacitor drive motor to send it to the point where the phase difference is zero? Yes, I am aware that is only adjusting the reactance of the load presented, but yes, I was aware the R component doesn't vary over a very wide range over the loop's operating frequency range, and that if X was tamed, the line losses would be acceptable. Owen -- Article: 218299 of rec.radio.amateur.antenna From: kashe@sonic.net Subject: Re: Aluminum tubing? Message-ID: References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> Date: Sun, 09 Oct 2005 02:18:12 GMT On Sat, 8 Oct 2005 12:53:00 -0500, "John N9JG" wrote: >Also, why do we say tube rather than valve? For the same reason we say toob instead of tshyoob. > >"Peter" wrote in message >news:4348f9f7.286775451@news.blueyonder.co.uk... >> On Wed, 05 Oct 2005 20:27:02 -0500, Allan Butler >> wrote: >> >>> I have tried all the local metal suppliers and several in the >>> Chicago >>>area to get 6061-T6 aluminum tubing from in very specific sizes. I need >>>to >> ^^^^^^^^ >> >> Why do you guys in the US always omit the "i" in aluminium ? >> >> Alsao why a car tire instead of tyre? >> >> Just asking ;-) >> >> >> Peter, G3PHO > Article: 218300 of rec.radio.amateur.antenna From: kashe@sonic.net Subject: Re: Aluminum tubing? Message-ID: References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> Date: Sun, 09 Oct 2005 02:19:49 GMT On Sat, 08 Oct 2005 14:43:58 -0500, Bob Bob wrote: >And being even further OT > >Brings further ambiguity to the term "retired" as well. (Like my 65 yo >father just had a wheel transplant) > >Since I live in W5... How does one say/spell Titanium/Titanum? > >I look at signs on the side of the road "Hiway" and cant for the life of >me work out what that means... > >Peter, its actually said in the US how it looks. Which is why we pronounce extraordinary with five or six syllables instead of two. > This gets real >confusing for me! (Along with driving on the WRONG side of the road! ) > >Cheers Bob W5/VK2YQA East Texas >(past the langauge test - can say "Y'all" easily) > >John N9JG wrote: > >>>Why do you guys in the US always omit the "i" in aluminium ? >>> >>>Alsao why a car tire instead of tyre? >>> >>>Just asking ;-) >>> >>> >>>Peter, G3PHO >> >> >> Article: 218301 of rec.radio.amateur.antenna From: kashe@sonic.net Subject: Re: Aluminum tubing? Message-ID: <0jvgk1d3790v4gmlete3gag868jh3dmk9p@4ax.com> References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> Date: Sun, 09 Oct 2005 02:21:03 GMT On Sat, 08 Oct 2005 20:24:09 GMT, Cecil Moore wrote: >Peter wrote: >> Also why a car tire instead of tyre? > >Why do your cars have bonnets even when it >isn't Easter? Why doesn't getting knocked up in England result in babies? Article: 218302 of rec.radio.amateur.antenna From: kashe@sonic.net Subject: Re: Aluminum tubing? Message-ID: References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> <7irl13-0nt.ln1@p400bob.personal.cox.net> Date: Sun, 09 Oct 2005 02:23:46 GMT On Sat, 08 Oct 2005 16:50:30 -0500, Bob Bob wrote: >Same argument I guess for having a hood like what an executioner wears! > >And what about the tree sans leaves, roots and branches in the rear of >the car? > >We could no doubt go on forever. I maintain though that it doesn't >matter how bad you spell, use colloquial terms or different languages. >What matters is that we allow for ambiguous meaning >and then dialogue to rectify misunderstanding.. I gotta say that's a pretty straightforward way to say it. :-) Eschew obfuscation whenever possible. >It is a lot of fun though! > >Bob > >Cecil Moore wrote: >> >> Why do your cars have bonnets even when it >> isn't Easter? Article: 218303 of rec.radio.amateur.antenna From: kashe@sonic.net Subject: Re: Aluminum tubing? Message-ID: References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> <71489$4348444b$97d558d8$4747@ALLTEL.NET> Date: Sun, 09 Oct 2005 02:24:36 GMT On Sat, 8 Oct 2005 18:11:27 -0400, "Fred W4JLE" wrote: >I guess it is because you folks just don't understand English. We also note >you misspell color as well. Their orthography is far more glamourous. :-) > >"Peter" wrote in message >news:4348f9f7.286775451@news.blueyonder.co.uk... >> On Wed, 05 Oct 2005 20:27:02 -0500, Allan Butler >> wrote: >> >> > I have tried all the local metal suppliers and several in the >Chicago >> >area to get 6061-T6 aluminum tubing from in very specific sizes. I need >to >> ^^^^^^^^ >> >> Why do you guys in the US always omit the "i" in aluminium ? >> >> Alsao why a car tire instead of tyre? >> >> Just asking ;-) >> >> >> Peter, G3PHO > Article: 218304 of rec.radio.amateur.antenna From: "Lee" References: Subject: Re: Re Magnetic Loop !!! Message-ID: Date: Sun, 09 Oct 2005 05:38:51 GMT "Owen Duffy" wrote in message news:v92fk15p4e5sh59fo4mkvvi8287ko2an8d@4ax.com... > On Sat, 08 Oct 2005 06:26:31 GMT, "Lee" > wrote: > > >To continue the saga...... Assuming it is a permag motor, reduce the motor voltage... add a > current limited driver to limit the torque, an electronic shear pin if > you like... except it doesn't shear. Yes, good idea......i`ll look into that. > I am assuming that you are trying to tune the reactance out, to >>>>>> achieve an acceptable VSWR on the line to the ATU/transceiver<<<< An ATU does not work too well with a magloop as the magloop has its own tuning capacitor (ATU) built in all that happens is that the antenna and feed are tuned as one....unless i misunderstand your comment!!!. . Have > you considered automating the capacitor drive. You could build a phase > detector (between V and I at the antenna input) as a sensor to control > the motor drive. Yes, but that is a bit too involved when pulse width modulation will do the job, albeit, manually.....good thought tho`...... Thanks for the input .... Lee.........G6ZSG..... > > Owen > -- Article: 218305 of rec.radio.amateur.antenna From: "Lee" References: Subject: Re: Re Magnetic Loop !!! Message-ID: Date: Sun, 09 Oct 2005 05:43:47 GMT "Cecil Moore" wrote in message news:acQ1f.9877$oO2.2032@newssvr27.news.prodigy.net... > Lee wrote: > > Seriously, any ideas to slow the tuning rate will be most welcome . > > What's wrong with a gear-head motor? I have some in my junk box. Wish it was in my junkbox!!! ;-) Lee....G6ZSG...... > -- > 73, Cecil http://www.qsl.net/w5dxp Article: 218306 of rec.radio.amateur.antenna From: "Lee" References: Subject: Re: Re Magnetic Loop !!! Message-ID: Date: Sun, 09 Oct 2005 05:50:33 GMT "Owen Duffy" wrote in message news:a6hgk11k51gevnc6psse3dcv7m8e8h3smn@4ax.com... > On Sat, 8 Oct 2005 21:36:59 +0000 (UTC), "Reg Edwards" > wrote: > > > > >"Owen Duffy" wrote in message > >news:ieegk15h4qanu1m7t8nu15hb45erg6vvc4@4ax.com... > >> On Sat, 08 Oct 2005 12:53:11 GMT, "Lee" > > > >> wrote: > >> > >> > > >> >Doesn`t work with a magloop!!!.....thanks anyway. > >> > >> Why is that? > >> > >> Owen > > > >========================== > >Because there is only one phase - that which corresponds to the motor > >driving voltage. > > Call me thick, I still don't understand why you can't sample the RF V > and I and feed them to a phase detector to provide an indication of > whether to adjust the capacitor up or down to achieve resonance (V in > phase with I). > > Owen > -- No doubt you can Owen, but that is a little beyond my present technical learning curve unfortunately.....but i`ll get there eventually, i`m learning more as i post!!!. Thanks. Lee.....G6ZSG.... Article: 218307 of rec.radio.amateur.antenna Message-ID: <4348D866.8070902@killspam.internode.on.net> Date: Sun, 09 Oct 2005 18:44:22 +1000 From: Alan Peake Subject: Emoto Rotator Hi all, Have been offered an unused Emoto 1102 rotator, without controller, for AUD200 . Q1 Does this sound like good value? Q2 Where would I look for a controller? Thanks, Alan VK2TWB Article: 218308 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Re Magnetic Loop !!! Date: Sun, 9 Oct 2005 11:35:45 +0000 (UTC) Message-ID: References: > There was an article in RadCom some years ago describing an auto-tuning > Top Band vertical, which used a simple inline phase detector and a > little DC tuning motor. ================================== Ian, A magloop is an altogether different kettle of fish to a top-band vertical. For a start, the Q of a magloop is in the order of 1000. For a top-band vertical it may be about 50. For most antennas it is about 10. What I would like to know is has anybody ever made an automatic tuner which works with a magloop. Or has manufactured one for sale? By the way, thanks for the Teslar papers although I am unable to run the programs. ---- Reg. Article: 218309 of rec.radio.amateur.antenna Subject: Re: Aluminum tubing? From: Bruce References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> Message-ID: Date: Sun, 09 Oct 2005 11:35:49 GMT kashe@sonic.net wrote in news:nfvgk11r9qfobufnj3lsbl23jn01tqv8k4@4ax.com: > On Sat, 08 Oct 2005 14:43:58 -0500, Bob Bob wrote: > >>And being even further OT >> >>Brings further ambiguity to the term "retired" as well. (Like my 65 yo >>father just had a wheel transplant) >> >>Since I live in W5... How does one say/spell Titanium/Titanum? >> >>I look at signs on the side of the road "Hiway" and cant for the life >>of me work out what that means... >> >>Peter, its actually said in the US how it looks. > > Which is why we pronounce extraordinary with five or six > syllables instead of two. > >> This gets real >>confusing for me! (Along with driving on the WRONG side of the road! >>) >> >>Cheers Bob W5/VK2YQA East Texas >>(past the langauge test - can say "Y'all" easily) >> >>John N9JG wrote: >> >>>>Why do you guys in the US always omit the "i" in aluminium ? You mean the second "i"? Probably because we spell it correctly: Aluminum. ;~) I suppose we could also ask why you need to pronounce the first "u" hard. Article: 218310 of rec.radio.amateur.antenna From: "jroske" Subject: Anyone Have Plans for Dual Band Beam 2m/70cm? Message-ID: Date: Sun, 09 Oct 2005 12:01:37 GMT Does anyone have plans for constructing a 2 meter/ 70 cm Dual band Beam? Any help would be appreciated. Thanks in advance Joe Roske KD8CAP Article: 218311 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Re Magnetic Loop !!! Date: Sun, 9 Oct 2005 17:38:42 +0000 (UTC) Message-ID: References: > Not fundamentally different - it only means the magloop tuning will be > more sensitive. The servo will still try to drive the system to > resonance at zero phase angle. ================================= Ian, what slightly worries me is - (1) The resistive component of antenna input impedance, as measured at the input of the small coupling loop, when the main loop is even only slightly off-resonant, is altogether different from 50 ohms but is not included in the bridge balancing process. The diameter of the coupling loop is fixed. Yet magnitude and phase adjustments react upon each other as is experienced by a human operator with two variable controls. (2) The coupling between the two loops is very loose. We are trying to adjust the main loop exactly to resonance via a means which is very insensitive to its resonant condition. Direct voltage and current sampling connections to the main loop itself are impossible. (3) We can imagine a situation where the impedance phase-angle is zero at the measuremnt point, and the green LEDs light up, but which does not correspond to exact resonance in the main loop. And exact resonance matters with a magloop. (4) Because the system is trying to reduce a phase angle to zero in the presence of two unknowns, instability can result. We can imagine the system continuously hopping about trying to find the zero. As you can see, I have difficulty in describing what I think happens circuitwise. But I shall be convinced only when somebody produces something which WORKS reliably without human intervention. It may be possible but where is it? ---- Regards, Reg, G4FGQ Article: 218312 of rec.radio.amateur.antenna Subject: Re: Aluminum tubing? From: Allan Butler Date: Sun, 09 Oct 2005 12:48:56 -0500 Message-ID: <1128880294_37@isp.n> References: <1128562179_21@isp.n> Thanks for the information on where to find aluminum for antenna projects. The idea of scrap yards would not be a bad one except one does not know what the alloy or temper is on the aluminum. If it isn't right, the first good wind would end up making a nice bundle to go back to the scrap yard. :-( The commercial locations that were given in the information are helpful. Even the Texas Towers site referring to a different alloy is a help. Now I can go back to the locals with a request for the different alloy and see if they have any of that in stock. Again, thanks everyone for the pertinent information. As for the spelling changes. I am an American. I do not speak English, I speak American. If I had put the English spelling on the tests that I took in school I would have failed. I put the American spelling on the tests and at least passed the tests. Schools don't like it when one tries to be a unique individual. Find out who changed the spelling in the past and point your blame thrower at them. Basically it boils down to this is the way we were taught to spell and speak. Maybe we really don't speak English after all these years. We may speak and write a totally different language of American that is based on the English language. If that is the case then there might be reason to believe the same thing is happening with Australia, South Africa and a few other parts of the world. As an example of this get someone from Australia and listen to them. Even better hold a conversation with them. Then find someone from South Africa and converse with them on something in a totally different setting. After talking to both of them one on one, get them both into the same room and introduce them to each other than get them talking to each other about anything you want. You will find that the two dialects are different. OK I know. It's Off Topic. :-) But I started the topic so I can twist it. Right? Again folks, thanks for the information and it will be very helpful. Bye, Cheerio, G'Day, Seeya, Talk ta All Yall Later. :-) ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- Article: 218313 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: V/I ratio is forced to Z0 Date: Sun, 9 Oct 2005 13:03:57 -0500 Message-ID: <1406-43495B8D-905@storefull-3258.bay.webtv.net> References: <+HzH8raNG+RDFAor@ifwtech.co.uk> Ian White, G/GM3SEK wrote: "An alternative possibility is that the Bird 43 does give valid readings by sampling at the point where it physically is." Bird claims + or - 5% of Full Scale accuracy for the Model 43. Why is there power from the reverse direction for a Bird Model 43 to indicate? There is no second generator sending power in the peverse direction. The reverse r-f comes from a reflection. The coax enforces a voltage to current ratio equal to Zo in each direction of flow. Zo is 50 ohms in the Model 43. Reflection does a peculiar thing. It produces a 180-degree phase reversal between a wave`s voltage and current. Bird uses the fact that the current is in-phase with the voltage in one direction of travel and out-of-phase in the opposite direction of travel to distinguish between the two directions. To distinguish, Bird takes a voltage sample and a current sample at the same point in a 50 ohm line. These two samples are scaled and calibrated to produce identical deflections of the power indicator. Out-of-phase samples thus cancel leaving the in-phase samples to produce double the deflection either would produce alone. This deflection is carefully calibrated in watts. Reversing the direction of the wattmeter element, reverses the sense of the direction indicated and reverses the direction in which the samples of voltage and current cancel. The Bird has been satisfactory for about a half century. Best regards, Richard Harrison, KB5WZI Article: 218314 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: V/I ratio is forced to Z0 Date: Sun, 9 Oct 2005 13:36:16 -0500 Message-ID: <9656-43496320-862@storefull-3254.bay.webtv.net> References: Owen wrote: "---I can understand Reg`s point that the direct way to measure VSWR requires sampling voltage or current over a quarter wave of line where you can find / observe the actual minimum and maximum." Yes, and the direct way to measure MPH would be to measure the number of miles and divide by the number of hours to get an average value. It`s not often done that way. Maybe about as often as people find maxima and minima on a transmission line and compute their ratio. It is more convenient and sufficiently accurate to use indirect methods for MPH and SWR. Best regards, Richard Harrison, KB5WZI Article: 218315 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Re Magnetic Loop !!! Date: Sun, 9 Oct 2005 14:23:51 -0500 Message-ID: <11615-43496E47-838@storefull-3251.bay.webtv.net> References: Reg, G4FGQ wrote: "It may be possible but where is it?" In the shortwave broadcast plant I worked in 50 years ago we had a 3.5 KW AM Raytheon "Autotune" transmitter we used to talk back to our program relay transmitting station in another country. We called it our "order-wire " transmitter. It or its twin were sometimes used for broadcasting but it was low in power for that job. This autotune transmitter had a rotary telephone dial on its panel for programming its mode, operating drequency, etc. You could instruct it to listen to instructions, then dial in A-3 for AM, followed by the frequency you wanted it to operate on, such as 15,925, hit the go button, then stand back and watch the knobs spin as it tuned itself up completely. including putting the desired power into a dummy load. A ready lamp informed you it was good to go on the air at the push of a button. It worked like a charm. Collins made autotune transmitters which are now military relics of WW-2. I never toyed with one of those. Best regards, Richard Harrison, KB5WZI Article: 218316 of rec.radio.amateur.antenna From: "Ken Taylor" References: <1lihotn31d6fk.a79lqxn15md6$.dlg@40tude.net> <46ednZll5fNJXtzeRVn-tw@adelphia.com> <1ld6l994pmuua.r714uw19bb3e$.dlg@40tude.net> <1q8o4xpm943m.f72nw6qcveot$.dlg@40tude.net> <5VY0f.16263$iM2.1337218@news.xtra.co.nz> <1l053cdkmzptz$.v3sj8zl2t047$.dlg@40tude.net> Subject: Re: Messaging, AM/FM *On Locomotive* dont hold your breath! Message-ID: Date: Mon, 10 Oct 2005 09:07:51 +1300 "Ari Silversteinn" wrote in message news:1l053cdkmzptz$.v3sj8zl2t047$.dlg@40tude.net... > On Thu, 6 Oct 2005 11:59:01 +1300, Ken Taylor wrote: > >> Thanks Jim, but I wouldn't bet on the facts getting in the way of this >> 'project'. >> >> Cheers. >> >> Ken > > Why do you say that? > > Here's a "heads up" for you, Ken. There are over ten FedGov agencies, > several legal teams and the rail lines that are working with diligence on > this, and similar, projects with the full intent of attempting to pull > this > off. > > While you sit on the sidelines and nay-say. > > If I had a dime for cheap comments like yours, I could fund this project > out of petty cash. So goes the nature of those who do and those who > comment > about the doers. > -- > Drop the alphabet for email It may be a fine project which will produce the goods, but let's look at the way you've brought it here: - you wanted help to get up a truck-mounted transmitted to over-ride all AM/FM communications in an area. You wanted to drive the truck at up to 70mph through a disaster/emergency area, for no adequately explained reason (the RF is going for a mile or two outside the area, so why drive the truck?). You got told why it's impractical as described. - you suddenly changed it to a loco mounted project. You struck gold on this one as there are people here who clearly have industry experience. You're not poo-poo'ing their skepticism, but certainly not fazed (may not be a bad thing....). Why not pour the funds into controlling all these uncontrolled level crossings instead of producing a 'box' to go on every loco that may drive through the US? - you are trying to get commercial advice in a Ham group - is this the right venue?? I'd have thought not, though it's certainly cheap. - having ten agencies etc etc on your side may get the project through, but is it the right solution to whichever problem it's attacking? - 'nay-sayers' are a pain-in-the-arse, agreed - no-one likes them! - but sometimes you need to hear the other side. Cheers. Ken Article: 218317 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Transmitter ALC Date: Sun, 9 Oct 2005 20:11:09 +0000 (UTC) Message-ID: References: <6shgk11bict76alt5j6gr0d0trekiu2gal@4ax.com> "Owen Duffy" wrote various ways and means of automatically controlling the power output of transmitters. Thanks very much. Presumably control is needed to limit the power dissipated in the output transistors which involves a time delay. And, which is a different thing, to place limits on the instantaneous collector/emitter voltage. In my Icom 735 transceiver the first control requirement appears to be met by by placing a limit on the DC collector current or power input. The second requirement appears to be met by feeding back a gain-control voltage proportional to the magnitude of the reflection coefficient of the load impedance. I may not be entirely correct. ---- Reg. Article: 218318 of rec.radio.amateur.antenna From: LRod Subject: Re: Messaging, AM/FM *On Locomotive* dont hold your breath! Message-ID: <7n0jk1tsj1kbpoig32hu24pmoibecha4hb@4ax.com> References: <46ednZll5fNJXtzeRVn-tw@adelphia.com> <1ld6l994pmuua.r714uw19bb3e$.dlg@40tude.net> <1q8o4xpm943m.f72nw6qcveot$.dlg@40tude.net> <5VY0f.16263$iM2.1337218@news.xtra.co.nz> <1l053cdkmzptz$.v3sj8zl2t047$.dlg@40tude.net> Date: Sun, 09 Oct 2005 21:52:26 +0100 On Mon, 10 Oct 2005 09:07:51 +1300, "Ken Taylor" wrote: >It may be a fine project which will produce the goods, but let's look at the >way you've brought it here: >- you wanted help to get up a truck-mounted transmitted to over-ride all >AM/FM communications in an area. You wanted to drive the truck at up to >70mph through a disaster/emergency area, for no adequately explained reason >(the RF is going for a mile or two outside the area, so why drive the >truck?). You got told why it's impractical as described. >- you suddenly changed it to a loco mounted project. You struck gold on this >one as there are people here who clearly have industry experience. You're >not poo-poo'ing their skepticism, but certainly not fazed (may not be a bad >thing....). Why not pour the funds into controlling all these uncontrolled >level crossings instead of producing a 'box' to go on every loco that may >drive through the US? It struck me from the very beginning as a solution looking for a problem. -- LRod Master Woodbutcher and seasoned termite Shamelessly whoring my website since 1999 http://www.woodbutcher.net Proud participant of rec.woodworking since February, 1997 Article: 218319 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Transmitter ALC Message-ID: References: <6shgk11bict76alt5j6gr0d0trekiu2gal@4ax.com> Date: Sun, 09 Oct 2005 21:09:08 GMT On Sun, 9 Oct 2005 20:11:09 +0000 (UTC), "Reg Edwards" wrote: > >"Owen Duffy" wrote various ways and means of automatically >controlling the power output of transmitters. Thanks very much. > >Presumably control is needed to limit the power dissipated in the >output transistors which involves a time delay. And, which is a >different thing, to place limits on the instantaneous >collector/emitter voltage. Another method of PA protection is thermal protection of the PA, sometimes integrated with cooling fan control. In my experience, where drive control is deployed, it reduces drive to prevent the heatsink exceeding about 60 deg C. I have found such protection commonly on commercial FM land mobile equipment (two way radios), some amateur FM mobiles, and less frequently in HF equipment. > >In my Icom 735 transceiver the first control requirement appears to be >met by by placing a limit on the DC collector current or power input. You are right, some radios do incorporate over-current protection of the PA. It is in some Icom radios (IC706IIG, IC7400 / IC746PRO), and I suspect many other Icoms will share this feature. Whilst probably intended for PA protection, it has the great benefit that the radio is less likely to draw excessive current while adjusting an ATU, and tripping over-current protection in a power supply. A radio that needs 16A in operation, but 25 during tune is a pain in the butt on a nominal 20A power supply with over current protection that kicks in above 22A! >The second requirement appears to be met by feeding back a >gain-control voltage proportional to the magnitude of the reflection >coefficient of the load impedance. I may not be entirely correct. As I described, and for example, from the IC706IIG service manual: "The reflected wave signal appears and increases on the antenna connector when the antenna is mismatched. The HF/50 MHz reflected signal level is detected at D10 (FILTER board), and is amplified at the APC amplifier (IC1091c) and applied to the ALC circuit as the reference voltage." You are probably (almost certainly) correct about the 735 having a "reflected power" limiting circuit, but Icom's view seems to be that if you want to read their description of how the radio works (if you had an interest in that sort of thing), you need to purchase the service manual. Where is all this leading Reg? Owen -- Article: 218320 of rec.radio.amateur.antenna From: Sluggo Subject: Re: US Tower TX-472 Base question Message-ID: References: <61Y1f.11967$q1.6140@newsread3.news.atl.earthlink.net> Date: Mon, 10 Oct 2005 03:16:38 GMT Thanks for the reply, David. I've pretty much decided to rent a tiny "track hoe" and dig down to the hardpan, to make sure it's not just some rocks I can remove... assuming the hardpan is, in fact, there, I'm going to just go with whatever depth I can get, and add about 20% to the total amount of concrete the mfr stated....and also do "overkill" on the rebar. I have both the original "T" base the tower was mounted on, as well as a brand-new one the fellow-ham I got it from gave me...concrete here in FL is rapidly approaching the cost of solid gold, "IF" you can get it, so, no room for mistakes... He also gave me the bolts that went with the new base, abt 3' long.... I *think* the bolts are UST items, everything else is. Thanks for your reply; this isn't the only place I've asked the question... and it's like pulling teeth to get a response worthy of consideration... Best 73, de Sluggo On Sat, 08 Oct 2005 22:48:34 GMT, "David Thompson" wrote: >Either will worK OK. The main point is to get the three base pins in the >correct position and vertical. The original TX-472 came with a plywood >template with a hole for each pin. Place that on the wood surrounding the >hole. My last hole was close to 4 X 4 X 7. > >If you don't have the 36 inch base pins with the bottom in a L (total length >is 42") you have two choices. You can get a new set from US Tower >(try to het HRO to order for you) or get 1" galvanized universal bolt >(probably have to order from a hardware store or Mcmaster-carr) and have the >bottom 6" bent at a right angle. > >I have moved my tower 4 times and have had good luck with the universal >bolt. > >73 Dave K4JRB > >"Sluggo" wrote in message >news:rk59k1tcgu4p2kctj5h4khr706lb5q59nt@4ax.com... >> I've got a TX-472; the problem is that at this QTH there is a >> limestone hardpan at about 5' depth. The original engineering >> drawing calls for a base of 4X4X7' deep. The latest drawing, >> available in .pdf form from their website, now calls for >> 5X5X6.5'. >> >> I'm hoping somebody here has run into a similar problem >> and can provide dimensions; UST says their engineer >> can draw it up, but for $300 or so. Needless to say, cheaper >> or preferably is always better. I can afford to send 'em >> the $ < I bought the tower used, it's not like they "owe" me>, >> but if I *have to* spend the bucks, I might be inclined to >> see if a local PE with the appropriate skills could do it, >> just in case there ever were an issue with permitting, etc., >> although I definately don't think that will happen, no permits >> req'd in this county for amateur towers below 200' at this time. >> >> Thanks for any help you can offer. >> >> 73, >> Sluggo >> >> (the email address in the headers is bogus, email to >> jrandy AT usa DOt Com if necessary) > Article: 218321 of rec.radio.amateur.antenna From: "Wayne P. Muckleroy" References: <1lihotn31d6fk.a79lqxn15md6$.dlg@40tude.net> Subject: Re: Emergency Messaging, AM/FM *On Locomotive* Message-ID: Date: Mon, 10 Oct 2005 06:10:28 GMT Is this guy done, now? "Ari Silversteinn" wrote in message news:1lihotn31d6fk.a79lqxn15md6$.dlg@40tude.net... > DHS has proposed a change in scenario. They want an on locomotive alerting > system that could be commandeered and driven at, near or about a disaster > site. Everything else stays more or less the same, overbroadcasting on > local AM/FM, power off the locomotive, selective or full frequency > broadcasting, train (s) to be in motion at all times. 20-30 second > messages > that would also combine a message to be aware that a locomotive (at speed) > will be flying by the at grade crossings. > > Comments? > -- > Drop the alphabet for email Article: 218322 of rec.radio.amateur.antenna From: "SH" References: <43422d26$1@news.wineasy.se> <4342fba9_3@news1.prserv.net> <43436b5d$1@news.wineasy.se> <74jA3LZkXuRDFw7g@g3ohx.demon.co.uk> <4347476c_3@news1.prserv.net> Subject: Re: Connecting several bandpass filters. Message-ID: <434a09ee$1@news.wineasy.se> Date: 10 Oct 2005 08:27:58 +0200 Hi All Just some more details. The signal is to be distributed to 4 of my neighbours and therefore the switch is out of the question unforunatly. The more i read about seperating almost each channels as Ian & Crazy George describes the more I like the idea. This will give me the posibility to adjust the level of each. And since I do want to do some DIY then building BP filters which not interact should be a task to overcome. The cray part of this project is that the only reason for that I want 21,39 and 47 on antenna two (TRIAX unix 100 vertikal pointing at 200 degrees) is because i am a TVDx'er and those three ones are extreme DTV fringe ones from 200 km away. Actually only the ch 38 on Ant. 2 is the only one to be used by my wife and neighbours. The antennas are place 100 meter away on the heighest point omf my property. So actually all this is because I want to be able to "snif" whether the conditions are good or not everywhere in the house and that is also the reason that i am interested in to get as much of the UHF band covered with ant 1 which is the WIZI EZ 74 (One of the biggest UHF ever produced). Its pointed toward 70 degrees (I live 8 km south south east of Roskilde in Denmark) and in that direction I got the baltic contries. The ant 1 is to be used for the following regular programmes 22/25 DTV schweden 23 local copenhagen 33, 43, 50 Analog Schweden The rest of the channels in the downlead from this is ant 3 31/53 Danish analogue TV (DR1 TV2), 51 soon to come Danish DTV. ant 4 ch 45 analogue Danish TV vertical (DR2) So its just one of those really crazy DIY projects to see if it is it at all possible.:-)) At the moment it all works with the 21, 39, 47 left out from ant 2 through a one channel amplifier. (I have put up an experimental unix 100 on 6 meters of waterpipe on the roof terrasse (very low WAF wife acceptance factor) to try out the 21,39,47 ) until I get this up and running. Best regards Svend Holby "Ian Jackson" wrote in message news:QYeKv0CTD4RDFwdS@g3ohx.demon.co.uk... > Re-reading Svend's mail, he wants Channels 22 to 37, 40 to 44, and 49 to > 64 (Antenna 1). He then needs to add Channel 21 and 38 + 39 (Antenna 2). > This should not be too difficult. > > Obviously, the filters will not totally reject channels which are close > (for example, the 22 to 37 filter will not reject 21 very well). There > will be a certain amount of unwanted noise outside the passband of each > filter, and ghosting (due to pick-up on the 'wrong' antenna) may not be > totally eliminated. It may be necessary to fit one or two notch filters. > > I would first fit a level-raising amplifier to the feed from each antenna. > There is nothing like having lots of signal level to play with! > > At the output of Amplifier 1, use a 4*-way CATV splitter to obtain four > feeds. The loss will be about 8dB (for a splitter which uses ferrite > transformers). Each output will be isolated from the others (typically by > about 25dB). > > [*Note: 2, 4 and 8-way splitters are 'standard building blocks' in the > world of cable TV. You can get 3-way and 6-way, but they are not easy to > find). > > To three of the feeds, fit bandpass filter for Channels 22 to 37, 40 to 44 > and 49 to 64. He can use the fourth output for monitoring. > > At the output of Amplifier 2, use another 4*-way CATV splitter to obtain 4 > feeds. To two of the feeds, fit bandpass filter for Channels 21 and 38+39. > > He now has six separate TV feeds. If he wants, he can fit in-line variable > attenuators to each to equalise the signal levels. > > The six TV feeds are then connected together using an 8*-way splitter (as > a combiner) or two 4-ways then a 2-way. There should be little interaction > between them. The loss will be about 11dB. > > Assuming a loss of 2dB for each filter, the total loss of this system will > be 8 + 11 + 2 = 21dB. > > All that remains it to design (or obtain). 'normal' filters for each block > of channels. There is a company in the UK which has a good range of > equipment for MATV and CATV: > http://www.taylorbros.co.uk > I don't see anything there which is exactly what Svend wants, but here > probably other companies in Europe which have can supply similar > equipment. > > Ian. > > > > > > > > In message <4347476c_3@news1.prserv.net>, Crazy George > writes >>Well, you know, it depends...... >> >>Optimally, one would like to have separate, independent antennas for each >>channel, the way we constructed the first CATV head ends up in the hills >>of >>Pennsylvania in the 1950s. But, then Scientific Atlanta and others >>designed LPD antennas which covered multiple channels coming from one >>general direction, and since tower space and loading was always a concern >>(don't forget multiple runs of low loss coax enter that equation also), >>multiple antennas gave way to fewer antennas and lots of signal processing >>down at the base of the tower. Some sites had racks and racks of gear. >> >>If the requirement is to provide signals to only one TV, a switch could be >>a >>good choice. On the other hand, if the design is for a whole house, or >>apartment complex or commercial building signal distribution system, then >>it >>gets progressively more complicated. Since Svend didn't specify, one had >>to >>conclude that he had already considered and rejected the easy solutions. >>-- >>Crazy George >> >>"Ian Jackson" wrote in message >>news:74jA3LZkXuRDFw7g@g3ohx.demon.co.uk... >>> With all those channels mixed together, it would be best to simply use >>> an A/B switch to switch between the two antennas. >>> Ian. >>> >>> >>> In message <43436b5d$1@news.wineasy.se>, SH writes >>> >Thanks for both you answers its nice to now i stil remember some theory >>> >eventhough its 10 years since i read some UHF theory (Ended up being a >>> >programmer :-)))) >>> > >>> >I think ill go for the notch version. I have made a lot of them and >>> >they >>are >>> >easy to build but I've noticed that it seams that 3 notches (adjusted >>> >to >>3 >>> >diff freq.) is some kind of limit. When i put in no. 4 it seams that >>> >the >>> >overall loss increases. >>> >Do I remember correctly when i state that 2 nothes on the same freq. >>should >>> >be a 1/4 wave apart??? >>> > >>> >Best regards >>> > >>> >Svend Holby >>> > >>> >"Crazy George" wrote in message >>> >news:4342fba9_3@news1.prserv.net... >>> >> Ben Jackson has some good points. You need not worry about audio, >>> >> usually, >>> >> as the FM capture takes care of the weaker signal. So, filtering the >>> >> video >>> >> carrier and near sidebands is all that is necessary. >>> >> >>> >> However, in answer to your question, the way you connect bandpass >>filters >>> >> in >>> >> parallel is with power dividers, amplifiers, and power dividers >>> >> again, >>> >> backwards as summers. Otherwise, controlling the out of band input >>> >> and >>> >> output impedances of several in parallel is a monumental, but >>> >> solvable >>> >> task. >>> >> Spice, anyone? >>> >> >>> >> -- >>> >> Crazy George >>> >> "SH" wrote in message >>> >> news:43422d26$1@news.wineasy.se... >>> >>> Hi >>> >>> >>> >>> I have come up with one of those crazy DYI ideas which I would like >>to >>> >> try >>> >>> to implement but one thing still remains. >>> >>> >>> >>> I have two UHF (TV) arial pointing in different directions and would >>like >>> >> to >>> >>> connect them together through BP filters to minimize noise. >>> >>> BP = Bandpass >>> >>> Antenna 1: UHF channel (Europe) BP 1 ch 22-37, BP 2 ch40 -44, BP 3 >>> >>> ch >>> >>> 49 - >>> >>> 68/ or high pass >>> >>> Antenna 2: UHF channel (Europe) BP 1 ch 21 / or low pass, BP 2 >>ch38 -39, >>> >> BP >>> >>> 3 ch 47 >>> >>> >>> >>> I have found formulas to design each section of BF but how to you >>connect >>> >>> several BP filters in parallel??? I have investigated some old TV >>filter >>> >> and >>> >>> they have a coil (12 WDG) in and out of each BP section but is that >>the >>> >> way >>> >>> to do it and how does it influence the design of each BP. >>> >>> >>> >>> The only approach that I can find is to split the signal into three >>> >>> (- >>> >> 6dB ) >>> >>> then feed each into a BP filter and the Combine them again (-6dB). >>This >>> >> will >>> >>> result in each BP section seeing 75 Ohms as they shouland they would >>not >>> >>> interfere with eachother. Ofcouse i would need a 20 dB amplifier to >>fix >>> >> the >>> >>> loss. >>> >>> >>> >>> But is there a better way. >>> >>> >>> >>> Best regards >>> >>> >>> >>> Svend Holby >>> >>> >>> >>> >>> >> >>> >> >>> > >>> > >>> >>> -- >>> >> >> > > -- > Article: 218323 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Re Magnetic Loop !!! Date: Mon, 10 Oct 2005 06:35:07 +0000 (UTC) Message-ID: References: Ian White wrote > I see your point... but what do you actually tune for, when you do > it manually? > =============================== Frequency is selected by the receiver, not the transmitter. The transmitter is OFF when I do it manually and I tune for maximum noise in the receiver. How do YOU do it? If I can't do it when the transmitter is ON then neither can an automatic ATU. It would have to be more clever than I am. ---- Regards, Reg, G4FGQ Article: 218324 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Transmitter ALC Date: Mon, 10 Oct 2005 07:04:05 +0000 (UTC) Message-ID: References: <6shgk11bict76alt5j6gr0d0trekiu2gal@4ax.com> "Owen Duffy" wrote > Where is all this leading Reg? ===================================== Owen, you sound very slightly suspicious. But it improves my and other readers education on a previously undiscussed topic of conversation. Thanks, Reg, G4FGQ. Article: 218325 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Re Magnetic Loop !!! Message-ID: <186kk1lgbofa6o2ki7e9jv3bgjb4d8110g@4ax.com> References: Date: Mon, 10 Oct 2005 07:43:34 GMT On Mon, 10 Oct 2005 08:18:35 +0100, Ian White G/GM3SEK wrote: >Reg Edwards wrote: >> >>Ian White wrote >>> I see your point... but what do you actually tune for, when you do > >>it manually? >>> >>=============================== >>Frequency is selected by the receiver, not the transmitter. >> >>The transmitter is OFF when I do it manually and I tune for maximum >>noise in the receiver. How do YOU do it? >> >I freely admit, I've never touched the things... just trying to be >helpful :-) > >But what do you think "maximum noise" means? You hope it's going to mean >maximum field strength when you come to transmit, but what does that >actually mean in terms of loop tuning conditions? > > >>If I can't do it when the transmitter is ON then neither can an >>automatic ATU. It would have to be more clever than I am. > >If we're not clever enough to build an automatic ATU for a magloop, it's >a sign that there's something about magloops we still need to know... >not abandon the idea. > >First of all, somebody needs to build a phase detector for an existing >manually tuned loop, and see what results it gives. Ian, Reg, I don't for a moment think automation of a loop tuner is trivial, but I don't think it is impractical with modern processor control techniques. For a practical solution, it will probably need some king of position sense from which to derive end limits and velocity for implementing a second order control loop. It is probably a lot like autotuning a PA tank (and that was done in closed loop linear systems decades ago), except that the loop Q is probably much higher and the tuning range wider. The same problems will be encountered in finding the true resonance where phase changes very quickly from a large positive value to a large negative value or vice versa depending on the direction of tuning. It would be interesting Reg, just the install an SWR meter (this is not a windup!) at your magloop, shut your eyes and tune it up on rx as you describe, then see whether is is close to minimum SWR )which will probably be at or very near zero reactance) on tx. To some extent, the tuner algorithms will be simpler than for a two to n variable tuner (many autotuners vary more than two components, they may switch in an autotransformer, or change from L to PI or PI-L configuration). I am more interested to hear from someone who says it can't be done, what they tried that didn't work. A remote autotuner could be just the thing that makes a magloop a very attractive, small, frequency versatile antenna (well, for those who don't have the antenna in the shack or very long arms). Owen -- Article: 218326 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Re Magnetic Loop !!! Date: Mon, 10 Oct 2005 09:53:29 +0000 (UTC) Message-ID: References: "Ian White G/GM3SEK" wrote in > If we're not clever enough to build an automatic ATU for a magloop, it's > a sign that there's something about magloops we still need to know... ==================================== We are able to analyse and predict the behaviour of magloops to any required degree of precision. What is missing is how both a magnitude-searching and phase-searching circuit of an automatic tuner works when denied access to the magnitude-searching component. When manually adjusting a tuner it is obvious to the operator that the controls INTERACT with each other. Both variable controls equally affect both magnitude and phase. That much can be gleaned from inspection of the circuitry. For example, in the case of a T-tuner with two variable capacitors, the operator cannot concentrate on one variable exclusively to the other. He continually has to swap from one to the other and obtain a balance by progressively closer approximations whilst keeping his eyes on the co-called SWR meter. An automatic tuner manages to complete the operation by varying both controls simultaneously. But it is obvious from observation of what the drive motors are doing, and the time taken to do it, that the circuit is behaving just like a human operator. Occasionally the motors even have to reverse and try again. When denied access to either one of the two variable controls, the automatic tuner doesn't know what to do next and would become lost. If the desired impedance magnitude is known to be 50 ohms and is somehow inserted in the circuit, this is of little assistance to how the circuit behaves because when the main loop is off-resonance the actual resistive component is miles away from 50 ohms yet the automatic tuner is obliged to do something about it. But without the ability to vary the diameter of the coupling loop, as I say, it is lost. So we need something different from and more sophisticated than the conventional automatic tuner with its relatively simple magnitude and phase-searching abilities. I'll believe it when I see one which works. Regarding your question about manual tuning up for maximum noise (or signal) in the receiver, at the frequency set by the receiver, reciprocity rules and fortunately, with modern transceivers, one can bawl into the microphone and answer a CQ call with confidence that it can be heard. But Ian, you already know all this. I have the time and I just like gabbing about it. I trust you are comfortably settling down in your new country. I have spent happy years, in bits, working in Scotland. It is a most civilised place. ---- Yours, Reg, G4FGQ Article: 218327 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Re Magnetic Loop !!! Date: Mon, 10 Oct 2005 10:08:09 +0000 (UTC) Message-ID: References: <0ptgk19booqq7eqjkgkq567klgke1cajtk@4ax.com> "Owen Duffy" wrote > Yes, I am aware that is only adjusting the reactance of the load > presented, but yes, I was aware the R component doesn't vary over a > very wide range over the loop's operating frequency range, and that if > X was tamed, the line losses would be acceptable. > ==================================== Line loss on transmit is relatively unimportant. What matters is accuracy of tuning up an extremely high Q loop on both transmit and receive. ---- Reg, G4FGQ Article: 218328 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Re Magnetic Loop !!! Date: Mon, 10 Oct 2005 11:33:48 +0000 (UTC) Message-ID: References: <186kk1lgbofa6o2ki7e9jv3bgjb4d8110g@4ax.com> "Owen Duffy" wrote > I am more interested to hear from someone who says it can't be done, > what they tried that didn't work. > =================================== Owen, I cannot but agree with everything you say and am inclined to say it can't be done automatically with anywhere near to the required degree of accuracy. The obvious automatic way of tuning the loop is to use a remotely controlled signal generator at the other end of the back yard and tune up for maximum signal on receive. This should not be very difficult to arrange but it is too uneconomic to be practical. So I'll stick to manual tuning. But I hasten to add that I hope this conversation does not deter anybody from experimenting with magloops because magloops are, by far, the most power-efficient of all the small, space-saving, neighbor-friendly antennas. Try one on the 160, 80 and 40 meter bands. At higher frequencies there's usually enough space to erect a dipole or an inverted-L which will perform at least as well. (Ian, you could perhaps do a useful article on the subject.) For the basic design, download program MAGLOOP4 from the website below. ........................................................... Regards from Reg, G4FGQ For Free Radio Design Software go to http://www.btinternet.com/~g4fgq.regp ........................................................... Article: 218329 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Re Magnetic Loop !!! References: Message-ID: Date: Mon, 10 Oct 2005 12:57:54 GMT Reg Edwards wrote: > If I can't do it when the transmitter is ON then neither can an > automatic ATU. It would have to be more clever than I am. It would be relatively easy to use the SWR meter driving current from an MFJ-259 to control the ATU motor. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218330 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Re Magnetic Loop !!! References: Message-ID: <4Ht2f.260$q%.5@newssvr12.news.prodigy.com> Date: Mon, 10 Oct 2005 13:06:08 GMT Reg Edwards wrote: > So we need something different from and more sophisticated than the > conventional automatic tuner with its relatively simple magnitude and > phase-searching abilities. If you remembered what frequency the mag loop had been tuned to last time, would that alleviate the need to know phase? The reason I ask is that is how I auto-tune my screwdriver without knowing phase. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218331 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Re Magnetic Loop !!! Date: Mon, 10 Oct 2005 13:17:01 +0000 (UTC) Message-ID: References: <4Ht2f.260$q%.5@newssvr12.news.prodigy.com> "Cecil Moore" wrote in message news:4Ht2f.260$q%.5@newssvr12.news.prodigy.com... > Reg Edwards wrote: > > So we need something different from and more sophisticated than the > > conventional automatic tuner with its relatively simple magnitude and > > phase-searching abilities. > > If you remembered what frequency the mag loop had been tuned > to last time, would that alleviate the need to know phase? > The reason I ask is that is how I auto-tune my screwdriver > without knowing phase. > -- > 73, Cecil http://www.qsl.net/w5dxp ======================================== Cecil, while you are tuning your screwdriver, which is not a magloop, phase and magnitude does not enter your head. Forget all about it! --- Reg Article: 218332 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Re Magnetic Loop !!! Date: Mon, 10 Oct 2005 13:18:27 +0000 (UTC) Message-ID: References: "Cecil Moore" wrote in message news:mzt2f.259$q%.231@newssvr12.news.prodigy.com... > Reg Edwards wrote: > > If I can't do it when the transmitter is ON then neither can an > > automatic ATU. It would have to be more clever than I am. > > It would be relatively easy to use the SWR meter driving > current from an MFJ-259 to control the ATU motor. > -- > 73, Cecil http://www.qsl.net/w5dxp ================================ Cecil, I keep telling you, there's no such thing as an SWR meter. --- Reg. Article: 218333 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Re Magnetic Loop !!! References: <4Ht2f.260$q%.5@newssvr12.news.prodigy.com> Message-ID: Date: Mon, 10 Oct 2005 13:36:23 GMT Reg Edwards wrote: > Cecil, while you are tuning your screwdriver, which is not a magloop, > phase and magnitude does not enter your head. Forget all about it! Watching the SWR meter while tuning my screwdriver while driving had always bothered me. I first installed an audio VCO so I wouldn't have to watch the SWR meter. Next I installed a flip-flop so I only had to get the screwdriver started in the right direction and didn't have to hold down the toggle switch. When the SWR starts dropping, an LM-339 shuts off power to the screwdriver motor. And it's all done while my IC-706 is in reduced power tune mode. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218334 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Re Magnetic Loop !!! References: Message-ID: <68u2f.263$q%.90@newssvr12.news.prodigy.com> Date: Mon, 10 Oct 2005 13:37:06 GMT Reg Edwards wrote: > Cecil, I keep telling you, there's no such thing as an SWR meter. The folks over on sci.physics.electromag disagree. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218335 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Re Magnetic Loop !!! Date: Mon, 10 Oct 2005 08:37:25 -0500 Message-ID: <9656-434A6E95-968@storefull-3254.bay.webtv.net> References: Reg, G4FGQ wrote: "The transmitter is OFF when I do it manually and I tune for maximum noise in the receiver." As Reg said, reciprocity rules. You can also satisfactotily tune an antenna to resonance by adjusting it for maximum output. When I was in Tierra del Fuego we had Land Rovers and boats equipped rith RCA single-sideband HF radios. The Rovers had whip antennas atop fiberglass boxes containing loading coils and motor-driven tap-changing switches. The coil base-loaded the whip. I routinely tuned the whips by switching my multimeter to the a-c range (it used germanium rectifiers) and tuning for a maximum meter indication. I chose meter-probe positions for a convenient scale indication. The above was accomplished with the transmitter ON and fed with a test tone driving it to put out some power. The whip was mostly non-directional so it made little difference where the r-f sensing antenna was placed. The tuning procedure worked fine even with the multimeter in the near-zone laying on the bonnet (hood) of the Rover. The capacitor tuning a high-Q loop could also be tuned for maximum output because that is your goal. The sampling antenna could be located almost anywhere but probably not in a null of the loop. Best regards, Richard Harrison, KB5WZI Article: 218336 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Re Magnetic Loop !!! References: <9656-434A6E95-968@storefull-3254.bay.webtv.net> Message-ID: Date: Mon, 10 Oct 2005 14:20:09 GMT Richard Harrison wrote: > The above was accomplished with the transmitter ON and fed with a test > tone driving it to put out some power. I don't know much about small loops. Modern transceivers, like my IC-706, have such good protection circuitry that it can be tuned into any load at full power. Is there anything in the design of a small loop that would prevent full power plus foldback tuning? -- 73, Cecil, http://www.qsl.net/w5dxp Article: 218337 of rec.radio.amateur.antenna From: Ari Silversteinn Subject: Re: Messaging, AM/FM *On Locomotive* dont hold your breath! Date: Mon, 10 Oct 2005 10:42:19 -0400 Message-ID: <1lzzmg4kuzre6.rg64haffcgku$.dlg@40tude.net> References: <46ednZll5fNJXtzeRVn-tw@adelphia.com> <1ld6l994pmuua.r714uw19bb3e$.dlg@40tude.net> <1q8o4xpm943m.f72nw6qcveot$.dlg@40tude.net> <5VY0f.16263$iM2.1337218@news.xtra.co.nz> <1l053cdkmzptz$.v3sj8zl2t047$.dlg@40tude.net> <7n0jk1tsj1kbpoig32hu24pmoibecha4hb@4ax.com> <1128917070.916999.240800@g14g2000cwa.googlegroups.com> On 9 Oct 2005 21:04:30 -0700, nm5k@wt.net wrote: > It struck me from the very beginning as a solution looking for a > problem.. > > Hummmm...I haven't read any of this thread, and after seeing > the initial page, decided it wasn't worth my time..."Not related > to any certain post". I was just curious , as the thread title started > to remind me of a old "Jethro Tull" song... Resume... > MK "Locomotive Breath" In the shuffling madness Of the locomotive breath, Runs the all-time loser, Headlong to his death. He feels the piston scraping -- Steam breaking on his brow -- Old Charlie stole the handle and The train won't stop going -- No way to slow down. He sees his children jumping off At the stations -- one by one. His woman and his best friend -- In bed and having fun. He's crawling down the corridor On his hands and knees -- Old Charlie stole the handle and The train won't stop going -- No way to slow down. He hears the silence howling -- Catches angels as they fall. And the all-time winner Has got him by the balls. He picks up Gideon's Bible -- Open at page one -- God stole the handle and The train won't stop going -- No way to slow down. -- Drop the alphabet for email Article: 218338 of rec.radio.amateur.antenna From: Ari Silversteinn Subject: Re: Emergency Messaging, AM/FM *On Locomotive* Date: Mon, 10 Oct 2005 10:43:33 -0400 Message-ID: <4nk9zi9ok6bm$.g865gdrr8vai$.dlg@40tude.net> References: <1lihotn31d6fk.a79lqxn15md6$.dlg@40tude.net> On Mon, 10 Oct 2005 06:10:28 GMT, Wayne P. Muckleroy wrote: > Is this guy done, now? We were until you reopened the thread, Wayne. duh. -- Drop the alphabet for email Article: 218339 of rec.radio.amateur.antenna From: w <"trollfuckingcentral(tm)"@trollcentral.org> Subject: Re: Messaging, AM/FM *On Locomotive* dont hold your breath! Date: Mon, 10 Oct 2005 10:45:05 -0400 Message-ID: <1rlo1e3qnf6hq$.o8jelz9eei76.dlg@40tude.net> References: <46ednZll5fNJXtzeRVn-tw@adelphia.com> <1ld6l994pmuua.r714uw19bb3e$.dlg@40tude.net> <1q8o4xpm943m.f72nw6qcveot$.dlg@40tude.net> <5VY0f.16263$iM2.1337218@news.xtra.co.nz> <1l053cdkmzptz$.v3sj8zl2t047$.dlg@40tude.net> <7n0jk1tsj1kbpoig32hu24pmoibecha4hb@4ax.com> On Sun, 09 Oct 2005 21:52:26 +0100, LRod wrote: > It struck me from the very beginning as a solution looking for a > problem. The you failed to read the thread. Article: 218340 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Re Magnetic Loop !!! Date: Mon, 10 Oct 2005 09:39:16 -0500 Message-ID: <7498-434A7D14-790@storefull-3252.bay.webtv.net> References: <68u2f.263$q%.90@newssvr12.news.prodigy.com> Reg, G4FGQ wrote: "Cecil, I keep telling you, there`s no such thing as an SWR meter." Terman says in his 1955 edition, page 99: "The standing-wave ratio S is one means of expressing the magnitude of the reflection coefficient;---." This, Terman illustrates can go either way via formulas. Rho is convertible to SWR and SWR is convertible to Rho. Why should an indication proportional to SWR not be so calibrated and called ? Best regards, Richard Harrison, KB5WZI Article: 218341 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Re Magnetic Loop !!! Date: Mon, 10 Oct 2005 10:02:44 -0500 Message-ID: <7499-434A8294-228@storefull-3252.bay.webtv.net> References: Cecil, W5DXP wrote: "Is there anything in the design of a small loop that would prevent full power plus foldback tuning" Maybe off-resonance operation. The small loop is always inductive but its reactance is high and its resistance is low, so it has a high-Q. It has almost uniform current thoughout, so this produces nulls on its axis. Best regards, Richard Harrison, KB5WZI Article: 218342 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Re Magnetic Loop !!! References: Message-ID: Date: Mon, 10 Oct 2005 15:17:29 GMT Reg Edwards wrote: > So we need something different from and more sophisticated than the > conventional automatic tuner with its relatively simple magnitude and > phase-searching abilities. > > I'll believe it when I see one which works. Reg, I just opened up my 2006 MFJ catalog. They have an "Automatic LoopTuner(TM)", the 300w MFJ-937. It's designed for approximately 1/10WL loops. -- 73, Cecil, http://www.qsl.net/w5dxp Article: 218343 of rec.radio.amateur.antenna From: "johan aeq" References: Subject: Re: Anyone Have Plans for Dual Band Beam 2m/70cm? Date: Mon, 10 Oct 2005 18:20:52 +0200 Message-ID: <92d71$434a966e$52ad139c$31683@news.versatel.nl> There ia a small program thatmakes it very simple to build a lpda antenne that works on two harmonic bands. I think it was LPDA.exe and was made by a german Ham. "jroske" schreef in bericht news:BE72f.1188$647.369@news01.roc.ny... > Does anyone have plans for constructing a 2 meter/ 70 cm Dual band Beam? Any > help would be appreciated. > > Thanks in advance > Joe Roske > KD8CAP > > Article: 218344 of rec.radio.amateur.antenna From: LRod Subject: Re: Messaging, AM/FM *On Locomotive* dont hold your breath! Message-ID: <6b9lk1dcpk51ub52o7hkekarga4ikrhbh6@4ax.com> References: <46ednZll5fNJXtzeRVn-tw@adelphia.com> <1ld6l994pmuua.r714uw19bb3e$.dlg@40tude.net> <1q8o4xpm943m.f72nw6qcveot$.dlg@40tude.net> <5VY0f.16263$iM2.1337218@news.xtra.co.nz> <1l053cdkmzptz$.v3sj8zl2t047$.dlg@40tude.net> <7n0jk1tsj1kbpoig32hu24pmoibecha4hb@4ax.com> <1rlo1e3qnf6hq$.o8jelz9eei76.dlg@40tude.net> Date: Mon, 10 Oct 2005 18:31:39 +0100 On Mon, 10 Oct 2005 10:45:05 -0400, w <"trollfuckingcentral(tm)"@trollcentral.org> wrote: >On Sun, 09 Oct 2005 21:52:26 +0100, LRod wrote: > >> It struck me from the very beginning as a solution looking for a >> problem. > >The you failed to read the thread. I read every post. -- LRod Master Woodbutcher and seasoned termite Shamelessly whoring my website since 1999 http://www.woodbutcher.net Proud participant of rec.woodworking since February, 1997 Article: 218345 of rec.radio.amateur.antenna From: "Jim" Subject: Need RDF Yagi alternative Date: Tue, 11 Oct 2005 01:03:34 -0400 Message-ID: This isn't strictly a Ham question, but I hope you all can help me anyway. I am using small transmitters in the 166-167 mhz range in some Box Turtle research I am doing. My RDF antenna is a 3 element Yagi designed via Yagicad 4.1 which works pretty well. It has 48db front/back and about 90 degrees beamwidth in the H pattern. This works well for initial locating......usually starting 1500 to 2000 feet >from my transmitter, but the closer I get, the more inaccurate it becomes. What kind of antenna design could I switch to when I get to close range that would have a narrower beam so I could pinpint my target? It would be nice to have something smaller than my 35" x 21" yagi for close in work, but the beam width is the primary concern. Yagicad doesn't let me design solely on beam width (at least I haven't figured out how) so is there another way to go on this?? Thanks Jim Article: 218346 of rec.radio.amateur.antenna From: nospam@nouce.bellatlantic.net Subject: Re: Need RDF Yagi alternative Message-ID: References: Date: Mon, 10 Oct 2005 18:51:50 GMT On Tue, 11 Oct 2005 01:03:34 -0400, "Jim" wrote: >This isn't strictly a Ham question, but I hope you all can help me anyway. > >I am using small transmitters in the 166-167 mhz range in some Box Turtle >research I am doing. My RDF antenna is a 3 element Yagi designed via >Yagicad 4.1 which works pretty well. It has 48db front/back and about 90 >degrees beamwidth in the H pattern. > >This works well for initial locating......usually starting 1500 to 2000 feet >from my transmitter, but the closer I get, the more inaccurate it becomes. > >What kind of antenna design could I switch to when I get to close range that >would have a narrower beam so I could pinpint my target? It would be nice >to have something smaller than my 35" x 21" yagi for close in work, but the >beam width is the primary concern. > >Yagicad doesn't let me design solely on beam width (at least I haven't >figured out how) so is there another way to go on this?? > >Thanks >Jim > You already got two good suggestions from others. Here's a third. Build a MOXON square, less gain than yagi but if built right the MOXON has a very distinct readward null, you exploit the null. Another small advantage is it's smaller than a 2 element yagi for the same band. Allison Article: 218347 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: Need RDF Yagi alternative References: Message-ID: <20rq13-5m2.ln1@p400bob.personal.cox.net> Date: Mon, 10 Oct 2005 14:11:30 -0500 Hi Jim Hams will quite often get involved in hidden transmitter hunts during field day games. You might be surprised at the expertise out there. Some notes/thoughts for you; - I'd be surprised that the yagi would exhibit 48dB F/B and if it did it would only be for a very narrow frequency range. This however isnt a huge problem. Even 20dB is more than ample for hidden TX finding. - Ensure that you arent cross polarized with the turtle antenna. It is possible for polarisation to change as the signal reflects off objects so reflected signal maybe stronger than the direct. This only gets to be a huge issue at cross polarised (say) plus or minus 10 degrees or so so just make sure you are in the ballpark. - Something that you modeled probably didnt allow for a ground so close and your body so near. What I am trying to get at is you may not be getting anything like the performance you expected because of these local detuning effects. - I'd suspect that the problem might actually be more in the receiver than antenna. As the signal gets stronger/closer the radio might be running out of signal reporting range,. ie everything is just over a certain value so it is treated as being at maximum. It is quite common under these conditions to switch in an amount of attenuation to reduce the signal to a more reportable figure. This usaully goes in the antenna feedline. - In addition to the above your receiver may not be very well shielded such that signal actually bypasses the antenna/coax path and thus gives you less peaks and nulls to go off. You can check this by placing a dummy load (usually 50 ohms) in the antenna cable socket and checking for the nearby signal. - The human body is excellent for using as a directional attenuator. If you had a simple omni antenna attached and only a few inches in front of your body you'll get maximum attenuation (lowest signal) when you are facing away from the target turtle. - If you antenna design isnt symetrical and there is an imbalance of currents in the coax you may get to receive a signal directly to the coax as well as the antenna. A few ferrite beads at the antenna feedpoint around the coax, coiling the coax in a 4" dia 5 turn loop or using some other form of balun (coaxial or otherwise might help. Obviously you can test this theory by playing with the coax orientation as well as the antennas. - Considering also using the null or side of the antenna. ie turn it at right angles to the turtle and where you get a very sharp loss of signal thats the direction (or 180 degrees out) the TX is. - Trying to narrow the beamwidth probably isnt a useful exercise with the size limitations you have. You stated 90 degrees (3db down) beamwidth. With (say) a 12 element yagi, 20ft long the beamwidth is around 38 degrees. Better but probably not useful for you. Hope this is useful to you. Oh and a question. Is the box turtle the one one that has the hinged flap in front? I found one on a busy road and I picked it up and moved it along in what I hope was the direction it was going. Had never seen one before! (New to the US) Cheers Bob W5/VK2YQA Jim wrote: > This isn't strictly a Ham question, but I hope you all can help me anyway. Article: 218348 of rec.radio.amateur.antenna From: Ari Silversteinn Subject: Re: Messaging, AM/FM *On Locomotive* dont hold your breath! Date: Mon, 10 Oct 2005 16:14:24 -0400 Message-ID: References: <46ednZll5fNJXtzeRVn-tw@adelphia.com> <1ld6l994pmuua.r714uw19bb3e$.dlg@40tude.net> <1q8o4xpm943m.f72nw6qcveot$.dlg@40tude.net> <5VY0f.16263$iM2.1337218@news.xtra.co.nz> <1l053cdkmzptz$.v3sj8zl2t047$.dlg@40tude.net> <7n0jk1tsj1kbpoig32hu24pmoibecha4hb@4ax.com> <1rlo1e3qnf6hq$.o8jelz9eei76.dlg@40tude.net> On Mon, 10 Oct 2005 10:27:28 -0700, Richard Clark wrote: > On Mon, 10 Oct 2005 10:45:05 -0400, w > <"trollfuckingcentral(tm)"@trollcentral.org> wrote: > >>On Sun, 09 Oct 2005 21:52:26 +0100, LRod wrote: >> >>> It struck me from the very beginning as a solution looking for a >>> problem. >> >>The you failed to read the thread. > No, Ari, that was not a requisite to come to that understanding. Uh, this wasn't Ari, check your headers. -- Drop the alphabet for email Article: 218349 of rec.radio.amateur.antenna From: microwaves@blueyonder.co.uk (Peter) Subject: Re: Aluminum tubing? Message-ID: <434cd876.474806555@news.blueyonder.co.uk> References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> Date: Mon, 10 Oct 2005 21:11:28 GMT On Sat, 08 Oct 2005 13:33:35 -0400, Amos Keag wrote: >Because it's ALUMINUM!!! > >Tyre is an ancient biblical city. Tire is that round thingee between my >automobile and the road surface. > Tire is what I do very rapidly when listen to a politician spout forth on the TV ... :-) Article: 218350 of rec.radio.amateur.antenna From: microwaves@blueyonder.co.uk (Peter) Subject: Re: Aluminum tubing? Message-ID: <434dd8f5.474932747@news.blueyonder.co.uk> References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> Date: Mon, 10 Oct 2005 21:13:03 GMT On Sat, 08 Oct 2005 14:43:58 -0500, Bob Bob wrote: >And being even further OT > >Brings further ambiguity to the term "retired" as well. (Like my 65 yo >father just had a wheel transplant) LOL!! Article: 218351 of rec.radio.amateur.antenna From: microwaves@blueyonder.co.uk (Peter) Subject: Re: Aluminum tubing? Message-ID: <434ed963.475043346@news.blueyonder.co.uk> References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> Date: Mon, 10 Oct 2005 21:14:00 GMT On Sun, 09 Oct 2005 11:35:49 GMT, Bruce wrote: > >You mean the second "i"? Probably because we spell it correctly: Aluminum. >;~) > >I suppose we could also ask why you need to pronounce the first "u" hard. Do we? I hadn't noticed ;-) Article: 218352 of rec.radio.amateur.antenna From: microwaves@blueyonder.co.uk (Peter) Subject: Re: Aluminum tubing? Message-ID: <434fd99b.475099587@news.blueyonder.co.uk> References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> Date: Mon, 10 Oct 2005 21:15:40 GMT On Sat, 08 Oct 2005 20:24:09 GMT, Cecil Moore wrote: >Peter wrote: >> Also why a car tire instead of tyre? > >Why do your cars have bonnets even when it >isn't Easter? You also give your car a trunk while we give it a boot! Article: 218353 of rec.radio.amateur.antenna From: microwaves@blueyonder.co.uk (Peter) Subject: Re: Aluminum tubing? Message-ID: <4350d9f1.475184919@news.blueyonder.co.uk> References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> <7irl13-0nt.ln1@p400bob.personal.cox.net> Date: Mon, 10 Oct 2005 21:16:49 GMT On Sat, 08 Oct 2005 16:50:30 -0500, Bob Bob wrote: >We could no doubt go on forever. I maintain though that it doesn't >matter how bad you spell, use colloquial terms or different languages. >What matters is that we allow for ambiguous meaning and then dialogue to >rectify misunderstanding.. That's what our rulers (President and Prime Minister) count on... confusion among the people! Article: 218354 of rec.radio.amateur.antenna From: microwaves@blueyonder.co.uk (Peter) Subject: Re: Aluminum tubing? Message-ID: <4351da2c.475244565@news.blueyonder.co.uk> References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> <0jvgk1d3790v4gmlete3gag868jh3dmk9p@4ax.com> Date: Mon, 10 Oct 2005 21:18:06 GMT On Sun, 09 Oct 2005 02:21:03 GMT, kashe@sonic.net wrote: > > > Why doesn't getting knocked up in England result in babies? Wow... that's cutting things close... I could add the word ass and fanny to the conversation we're having but I'd better not ! Peter, G3PHO Article: 218355 of rec.radio.amateur.antenna From: "Ken Taylor" References: <46ednZll5fNJXtzeRVn-tw@adelphia.com> <1ld6l994pmuua.r714uw19bb3e$.dlg@40tude.net> <1q8o4xpm943m.f72nw6qcveot$.dlg@40tude.net> <5VY0f.16263$iM2.1337218@news.xtra.co.nz> <1l053cdkmzptz$.v3sj8zl2t047$.dlg@40tude.net> <7n0jk1tsj1kbpoig32hu24pmoibecha4hb@4ax.com> <1128917070.916999.240800@g14g2000cwa.googlegroups.com> <1lzzmg4kuzre6.rg64haffcgku$.dlg@40tude.net> Subject: Re: Messaging, AM/FM *On Locomotive* dont hold your breath! Message-ID: Date: Tue, 11 Oct 2005 10:29:42 +1300 "Ari Silversteinn" wrote in message news:1lzzmg4kuzre6.rg64haffcgku$.dlg@40tude.net... > On 9 Oct 2005 21:04:30 -0700, nm5k@wt.net wrote: > >> It struck me from the very beginning as a solution looking for a >> problem.. >> >> Hummmm...I haven't read any of this thread, and after seeing >> the initial page, decided it wasn't worth my time..."Not related >> to any certain post". I was just curious , as the thread title started >> to remind me of a old "Jethro Tull" song... Resume... >> MK > > "Locomotive Breath" > > In the shuffling madness > Of the locomotive breath, > Runs the all-time loser, > Headlong to his death. > He feels the piston scraping -- > Steam breaking on his brow -- > Old Charlie stole the handle and > The train won't stop going -- > No way to slow down. > He sees his children jumping off > At the stations -- one by one. > His woman and his best friend -- > In bed and having fun. > He's crawling down the corridor > On his hands and knees -- > Old Charlie stole the handle and > The train won't stop going -- > No way to slow down. > He hears the silence howling -- > Catches angels as they fall. > And the all-time winner > Has got him by the balls. > He picks up Gideon's Bible -- > Open at page one -- > God stole the handle and > The train won't stop going -- > No way to slow down. > > -- I don't like the project, but I like the messenger. :-) Cheers. Ken Article: 218356 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Aluminum tubing? References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> <0jvgk1d3790v4gmlete3gag868jh3dmk9p@4ax.com> <4351da2c.475244565@news.blueyonder.co.uk> Message-ID: <07B2f.242$dO2.52@newssvr29.news.prodigy.net> Date: Mon, 10 Oct 2005 21:33:48 GMT Peter wrote: > I could add the word ass and fanny to the conversation we're having > but I'd better not ! In England, a friend of mine was introduced thusly: "Hey Everyone! Here's a friend from America! He's Randy!" Randy wondered why everyone was laughing. -- 73, Cecil, http://www.qsl.net/w5dxp Article: 218357 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Re Magnetic Loop !!! Message-ID: References: <186kk1lgbofa6o2ki7e9jv3bgjb4d8110g@4ax.com> Date: Mon, 10 Oct 2005 21:43:23 GMT On Mon, 10 Oct 2005 11:33:48 +0000 (UTC), "Reg Edwards" wrote: ... >At higher frequencies >there's usually enough space to erect a dipole or an inverted-L which >will perform at least as well. (Ian, you could perhaps do a useful >article on the subject.) > ... I wrote an article on the Inverted L with a remote autotuner (designed for end-fed wires) some time ago. The configuration, it is frequency agile, very convenient when integrated with transeiver auto-tune controls, and works a treat. The most significant downside (like most Marconi, Windom, Long Wire etc configs) is from an EMR safety point of view, it has a radiator within reach of people standing on the ground. The article is at http://www.vk1od.net/InvertedL/InvertedL.htm . With the experience of using such a configuration, I reckon that a magloop with an remote autotuner designed specifically for a magloop would be a great option for people with very little space, better than Echolink! Reg, if you have an expression for the loop inductance and resistance as a function of frequency, and we could make the assumption that the coupling coil is a broadband ideal transformer with a fixed z ratio or otherwise characterise the transformation as a function of frequency, I could do a software simulation of an autotuner... be an interesting project. BTW, the tuner values in the article above are found through simulation of an automated L tuner, but the 3 variable binary searching algorithm used for performance would not work for a loop. Owen -- Article: 218358 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Re Magnetic Loop !!! Message-ID: References: <9656-434A6E95-968@storefull-3254.bay.webtv.net> Date: Mon, 10 Oct 2005 21:52:06 GMT On Mon, 10 Oct 2005 14:20:09 GMT, Cecil Moore wrote: ... >I don't know much about small loops. Modern transceivers, >like my IC-706, have such good protection circuitry that >it can be tuned into any load at full power. Is there ... I know it is common practice to tune screwdrivers for max power out >from IC706s (tuning for "maximum smoke"), but is that good for the tuner? Perhaps that is why Icom incorporated low power tuning of its system tuners. The AH4 actually presents a very limited range of Z to the radio, it effectively introduces a small attenuator at the tuner input when tuning. So the radio is limited to around 10W, the Z excursions are limited, and the tuner relays operate at quite low power. I wonder what they know that we don't? Perhaps it is why Kenwood drops carrier before each relay operation in autotuning the TS2000 internal tuner. (Some of their earlier models have a reputation for tuner relay failure.) It may be that tuning screwdrivers under full power isn't detrimental (I just don't know), but it is probably not safe to generalise. Owen -- Article: 218359 of rec.radio.amateur.antenna From: "Hal Rosser" References: Subject: Re: Anyone Have Plans for Dual Band Beam 2m/70cm? Message-ID: Date: Mon, 10 Oct 2005 17:58:48 -0400 "jroske" wrote in message news:BE72f.1188$647.369@news01.roc.ny... > Does anyone have plans for constructing a 2 meter/ 70 cm Dual band Beam? Any > help would be appreciated. > I've seen a quad set up for dual bands. The elements for the 70 cm band are so small, they don'r interefere with the 2m band Article: 218360 of rec.radio.amateur.antenna From: Allodoxaphobia Subject: Re: Aluminum tubing? Date: 10 Oct 2005 22:51:45 GMT Message-ID: References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> <0jvgk1d3790v4gmlete3gag868jh3dmk9p@4ax.com> <4351da2c.475244565@news.blueyonder.co.uk> <07B2f.242$dO2.52@newssvr29.news.prodigy.net> On Mon, 10 Oct 2005 17:47:59 -0400, Amos Keag wrote: > Cecil Moore wrote: >> Peter wrote: >> >>> I could add the word ass and fanny to the conversation we're having >>> but I'd better not ! >> >> In England, a friend of mine was introduced thusly: >> "Hey Everyone! Here's a friend from America! He's Randy!" >> Randy wondered why everyone was laughing. > > I'm ignorant [technical usage] please tell me why! I suppose that includes "web ignorant", too... http://www.google.com/search?&q=define:Randy Article: 218361 of rec.radio.amateur.antenna From: David Subject: Re: How to model on EZNEC References: <9hh1f.9103$U51.3133@news-server.bigpond.net.au> <7etfk1lpvpspfgi7u6vd8u0bm4kc463i44@4ax.com> <0jw2f.9312$y_1.3496@edtnps89> <8g8lk15u9hecqslo7n3udnr6jjpkbjnl7p@4ax.com> Message-ID: <7hC2f.14358$U51.7097@news-server.bigpond.net.au> Date: Mon, 10 Oct 2005 22:52:51 GMT I have tried entering the model shown in EZNEC 4 The "View" of the antenna looks fine but when I try to run the simulation it reports that it cannot because the gain is negative. I then changed from azimuth to elevation simulation but this time it reported the maxim 500 segments were exceeded. I then reduce the segments slightly but now the program reports Runtime error M6201: Math Sqrt Domain error. ie. Cannot get the model to work using EZNEC. I'll see if it will run in MNANA. Richard Clark wrote: > On Mon, 10 Oct 2005 16:05:16 GMT, "Frank" > wrote: > > >>My model is only valid providing the coax has no current on the exterior of >>the shield. All I did was extend one leg of the dipole by the length >>specified, but not actually connected to it; with a 1.2" gap. As per the >>following sketch. >> >>----------o---------- ---------- >> dipole extension >> >>Do you think it makes sense? It is the only way I could think of modeling >>it with NEC. > > > Hi Frank, > > No. The extension lies in the null of the dipole. As such, it would > be no mystery that it has so little influence. > > To model it correctly requires some form of cage or skirt of wires as > Wes has provided in this thread. > > 73's > Richard Clark, KB7QHC Article: 218362 of rec.radio.amateur.antenna Subject: Re: Need RDF Yagi alternative From: Bruce References: <20rq13-5m2.ln1@p400bob.personal.cox.net> Message-ID: Date: Mon, 10 Oct 2005 23:09:19 GMT Bob Bob wrote in news:20rq13-5m2.ln1@p400bob.personal.cox.net: > Hi Jim > > Hams will quite often get involved in hidden transmitter hunts during > field day games. You might be surprised at the expertise out there. > > Some notes/thoughts for you; > > > - I'd suspect that the problem might actually be more in the receiver > than antenna. As the signal gets stronger/closer the radio might be > running out of signal reporting range,. ie everything is just over a > certain value so it is treated as being at maximum. It is quite common > under these conditions to switch in an amount of attenuation to reduce > the signal to a more reportable figure. This usaully goes in the > antenna feedline. > > - In addition to the above your receiver may not be very well shielded > such that signal actually bypasses the antenna/coax path and thus > gives you less peaks and nulls to go off. You can check this by > placing a dummy load (usually 50 ohms) in the antenna cable socket and > checking for the nearby signal. Ahhh, you beat me to this. Now, if the receiver IS well shielded enough, if you can insert a switchable attenuator in the coax, you can reduce the signal strength significantly...and, FM receivers get very non-linear below about 20dB quieting, they quiet faster than the actual input. In otherwords, you could get 3-4 dB quieting change for 1dB of singal change. What this will do is make you antenna pattern SEEM narrower. What I used to do was to change to an RF field strengtth meter with a small cavity filter tuned to the frequency I was hunting when I got really close. > > - The human body is excellent for using as a directional attenuator. > If you had a simple omni antenna attached and only a few inches in > front of your body you'll get maximum attenuation (lowest signal) when > you are facing away from the target turtle. YES! But, you need to keep you body completely symetrical, stick an elbow out and you will distort the pattern. Also, when the signal gets large enough, remove the antenna. -Bruce Article: 218363 of rec.radio.amateur.antenna From: "Jim" References: <0PWdncgoqtIVL9feRVn-gw@comcast.com> Subject: Re: Need RDF Yagi alternative Date: Tue, 11 Oct 2005 06:29:39 -0400 Message-ID: <84b0e$434af850$d80c392d$23119@NAXS.COM> Believe me, the transmiters are not well filtered at all. In close range I easily get 2nd, 3rd, 5th, etc. harmonics. I'd try the 3rd harmonic antenna, but my receiver doesn't go beyond 173 mhz or so, so I can't receive the 3rd harmonic. I thought I'd be smart and have Yagicad design an antenna for the 2nd harmonic and then use it with my current receiver. I suppose you can guess the results from that failure...there is almost no null or beam width at all (360 degrees I guess). Oh, well. Thanks Jim "Larry Benko" wrote in message news:0PWdncgoqtIVL9feRVn-gw@comcast.com... > Jim wrote: > > This isn't strictly a Ham question, but I hope you all can help me anyway. > > > > I am using small transmitters in the 166-167 mhz range in some Box Turtle > > research I am doing. My RDF antenna is a 3 element Yagi designed via > > Yagicad 4.1 which works pretty well. It has 48db front/back and about 90 > > degrees beamwidth in the H pattern. > > > > This works well for initial locating......usually starting 1500 to 2000 feet > > from my transmitter, but the closer I get, the more inaccurate it becomes. > > > > What kind of antenna design could I switch to when I get to close range that > > would have a narrower beam so I could pinpint my target? It would be nice > > to have something smaller than my 35" x 21" yagi for close in work, but the > > beam width is the primary concern. > > > > Yagicad doesn't let me design solely on beam width (at least I haven't > > figured out how) so is there another way to go on this?? > > > > Thanks > > Jim > > > > > > Jim, > > Assuming your transmitters are NOT super well filtered I would build a > yagi for 3 times the frequency (498-501MHz) and listen on that frequency > when very close. Very few transmitters will be so clean as to not be > able to hear the 3rd harmonic. I DF and do running ARDF very often and > if you don't mind the small second antenna and you have a receiver that > can tune to the 3rd harmonic this will get you both the needed > attenuation for being close and the ability to pinpoint the source. > > 73, > Larry, W0QE Article: 218364 of rec.radio.amateur.antenna From: "Dale Parfitt" References: Subject: Re: Anyone Have Plans for Dual Band Beam 2m/70cm? Message-ID: Date: Mon, 10 Oct 2005 23:42:09 GMT "Hal Rosser" wrote in message news:FsB2f.11687$ke.980@bignews3.bellsouth.net... > > "jroske" wrote in message > news:BE72f.1188$647.369@news01.roc.ny... >> Does anyone have plans for constructing a 2 meter/ 70 cm Dual band Beam? > Any >> help would be appreciated. >> > I've seen a quad set up for dual bands. > The elements for the 70 cm band are so small, they don'r interefere with > the > 2m band > >How about the 2M elements being seen by the 70cM elements- close to >resonant at 3 wavelengths circumference? Dale W4OP Article: 218365 of rec.radio.amateur.antenna From: "Jim" References: <20rq13-5m2.ln1@p400bob.personal.cox.net> Subject: Re: Need RDF Yagi alternative Date: Tue, 11 Oct 2005 06:47:49 -0400 Message-ID: <650c$434afc93$d80c392d$667@NAXS.COM> True, I haven't thought of everything, but I have done this: The yagicad design, which others have used very successfully for foxhunting antennas, should work o.k. at 3 or 4 feet above the ground, right? My transmitter antennas are horizontal trailing insulated wire. I have a fairly long cable so am able to hold it at arm's length from my body. It does have a very good null and I use both front and null in my RDFing. My radio might not be the best as far as sheilding.....it is plastic cased. So I made a fiderglass holster for it with aluminum screen embedded in the fiberglass resin all the way around...kind of like a Faraday cage. I don't really know how this helps. It is not grounded, and I haven't really tested it out all that much. At a fair range I can receive my transmitters by connecting a rubber ducky antenna, and kill them when it is removed. SOMETIMES using my body to block the rubber ducky gives me a good null....but not good enough to RDF with. Yes, the Box Turtle (several species in North America) is the one with the hinge on it's plasteron ( the bottom "shell") which allows it to pull entirely in its shell and close up. Box Turtle numbers are decreasing thoughout thier ranges and will probably be rare over the next 50 to 100 years or so in many areas. Thanks Jim "Bob Bob" wrote in message news:20rq13-5m2.ln1@p400bob.personal.cox.net... > Hi Jim > > Hams will quite often get involved in hidden transmitter hunts during > field day games. You might be surprised at the expertise out there. > > Some notes/thoughts for you; > > - I'd be surprised that the yagi would exhibit 48dB F/B and if it did it > would only be for a very narrow frequency range. This however isnt a > huge problem. Even 20dB is more than ample for hidden TX finding. > > - Ensure that you arent cross polarized with the turtle antenna. It is > possible for polarisation to change as the signal reflects off objects > so reflected signal maybe stronger than the direct. This only gets to be > a huge issue at cross polarised (say) plus or minus 10 degrees or so so > just make sure you are in the ballpark. > > - Something that you modeled probably didnt allow for a ground so close > and your body so near. What I am trying to get at is you may not be > getting anything like the performance you expected because of these > local detuning effects. > > - I'd suspect that the problem might actually be more in the receiver > than antenna. As the signal gets stronger/closer the radio might be > running out of signal reporting range,. ie everything is just over a > certain value so it is treated as being at maximum. It is quite common > under these conditions to switch in an amount of attenuation to reduce > the signal to a more reportable figure. This usaully goes in the antenna > feedline. > > - In addition to the above your receiver may not be very well shielded > such that signal actually bypasses the antenna/coax path and thus gives > you less peaks and nulls to go off. You can check this by placing a > dummy load (usually 50 ohms) in the antenna cable socket and checking > for the nearby signal. > > - The human body is excellent for using as a directional attenuator. If > you had a simple omni antenna attached and only a few inches in front of > your body you'll get maximum attenuation (lowest signal) when you are > facing away from the target turtle. > > - If you antenna design isnt symetrical and there is an imbalance of > currents in the coax you may get to receive a signal directly to the > coax as well as the antenna. A few ferrite beads at the antenna > feedpoint around the coax, coiling the coax in a 4" dia 5 turn loop or > using some other form of balun (coaxial or otherwise might help. > Obviously you can test this theory by playing with the coax orientation > as well as the antennas. > > - Considering also using the null or side of the antenna. ie turn it at > right angles to the turtle and where you get a very sharp loss of signal > thats the direction (or 180 degrees out) the TX is. > > - Trying to narrow the beamwidth probably isnt a useful exercise with > the size limitations you have. You stated 90 degrees (3db down) > beamwidth. With (say) a 12 element yagi, 20ft long the beamwidth is > around 38 degrees. Better but probably not useful for you. > > Hope this is useful to you. > > Oh and a question. Is the box turtle the one one that has the hinged > flap in front? I found one on a busy road and I picked it up and moved > it along in what I hope was the direction it was going. Had never seen > one before! (New to the US) > > Cheers Bob W5/VK2YQA > > Jim wrote: > > This isn't strictly a Ham question, but I hope you all can help me anyway. Article: 218366 of rec.radio.amateur.antenna From: "Jim" References: <20rq13-5m2.ln1@p400bob.personal.cox.net> Subject: Re: Need RDF Yagi alternative Date: Tue, 11 Oct 2005 07:01:26 -0400 Message-ID: <13eab$434affc3$d80c392d$10862@NAXS.COM> I have a homebrew analog attenuator that has male and female BNC connectors that I can connect when necessary. It is variable 0 to 10 dB, and this sometimes helps a lot, but not always, and not when I get within 40 feet or so. I know this is not a problem when foxhunting (or is it?), but when there is a lot of brush and brambles and holes and such, I sure would like to reduce my hands and knees search area. I worked with a researcher once that was able to locate his Bog Turtles under water within 6" to a foot via "pointing" the antenna (150 mhz). When the antenna pointed into the mud, he could stick in his hand and pull out the turtle......now that's good RDFing, and I don't expect anything like that, although the next time I'm taking measurements of his antenna to duplicate it if I can. I am not familiar with a "cavity filter". I'll do some Googling on that. Can you fill me in on it's use? Thanks JIm "Bruce" wrote in message news:Xns96EBC33DC1298xxxyyyzzz@216.77.188.18... > Bob Bob wrote in > news:20rq13-5m2.ln1@p400bob.personal.cox.net: > > > Hi Jim > > > > Hams will quite often get involved in hidden transmitter hunts during > > field day games. You might be surprised at the expertise out there. > > > > Some notes/thoughts for you; > > > > > > - I'd suspect that the problem might actually be more in the receiver > > than antenna. As the signal gets stronger/closer the radio might be > > running out of signal reporting range,. ie everything is just over a > > certain value so it is treated as being at maximum. It is quite common > > under these conditions to switch in an amount of attenuation to reduce > > the signal to a more reportable figure. This usaully goes in the > > antenna feedline. > > > > - In addition to the above your receiver may not be very well shielded > > such that signal actually bypasses the antenna/coax path and thus > > gives you less peaks and nulls to go off. You can check this by > > placing a dummy load (usually 50 ohms) in the antenna cable socket and > > checking for the nearby signal. > > Ahhh, you beat me to this. > > Now, if the receiver IS well shielded enough, if you can insert a > switchable attenuator in the coax, you can reduce the signal strength > significantly...and, FM receivers get very non-linear below about 20dB > quieting, they quiet faster than the actual input. In otherwords, you > could get 3-4 dB quieting change for 1dB of singal change. What this will > do is make you antenna pattern SEEM narrower. > > What I used to do was to change to an RF field strengtth meter with a > small cavity filter tuned to the frequency I was hunting when I got > really close. > > > > > - The human body is excellent for using as a directional attenuator. > > If you had a simple omni antenna attached and only a few inches in > > front of your body you'll get maximum attenuation (lowest signal) when > > you are facing away from the target turtle. > > YES! But, you need to keep you body completely symetrical, stick an elbow > out and you will distort the pattern. Also, when the signal gets large > enough, remove the antenna. > > > -Bruce Article: 218367 of rec.radio.amateur.antenna From: David Subject: Re: How to model on EZNEC References: <9hh1f.9103$U51.3133@news-server.bigpond.net.au> <7etfk1lpvpspfgi7u6vd8u0bm4kc463i44@4ax.com> <0jw2f.9312$y_1.3496@edtnps89> <8g8lk15u9hecqslo7n3udnr6jjpkbjnl7p@4ax.com> <7hC2f.14358$U51.7097@news-server.bigpond.net.au> Message-ID: Date: Tue, 11 Oct 2005 01:05:32 GMT Some ninkum poop (me) had the units set to wavelengths instead of inches. It does run now. Thanks for the model, it gives me a starting point to "play" with the thing. Richard Clark wrote: > On Mon, 10 Oct 2005 22:52:51 GMT, David wrote: > > >>Cannot get the model to work using EZNEC. > > > Hi David, > > Sounds like you got a wire crossed somewhere. > > 73's > Richard Clark, KB7QHC Article: 218368 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Aluminum tubing? References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> <0jvgk1d3790v4gmlete3gag868jh3dmk9p@4ax.com> <4351da2c.475244565@news.blueyonder.co.uk> <07B2f.242$dO2.52@newssvr29.news.prodigy.net> Message-ID: <3iE2f.344$q%.18@newssvr12.news.prodigy.com> Date: Tue, 11 Oct 2005 01:10:23 GMT Amos Keag wrote: > Cecil Moore wrote: >> In England, a friend of mine was introduced thusly: >> "Hey Everyone! Here's a friend from America! He's Randy!" >> Randy wondered why everyone was laughing. > > I'm ignorant [technical usage] please tell me why! I think it's because "randy" in England means the same thing as "horny" in the US. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218369 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Re Magnetic Loop !!! References: <9656-434A6E95-968@storefull-3254.bay.webtv.net> Message-ID: Date: Tue, 11 Oct 2005 01:19:21 GMT Owen Duffy wrote: > I know it is common practice to tune screwdrivers for max power out > from IC706s (tuning for "maximum smoke"), but is that good for the > tuner? The SG-230 seems to handle 100 watts just fine. It is interesting to listen to an autotuner tune up a transmitter equipped with foldback. Clickidy-Click, the signal goes from S5 to S9. If the foldback circuitry failed, then there would probably be a bad outcome. Assuming foldback and reflected power not invading the remote tuner, I don't see why any harm would be done. 'Course, I'm suffering from macular degeneration. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218370 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Anyone Have Plans for Dual Band Beam 2m/70cm? References: Message-ID: <1sE2f.349$q%.118@newssvr12.news.prodigy.com> Date: Tue, 11 Oct 2005 01:21:01 GMT Hal Rosser wrote: > The elements for the 70 cm band are so small, they don'r interefere with the > 2m band But the opposite may not be true since 444/3=148. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218371 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Need RDF Yagi alternative Date: Mon, 10 Oct 2005 20:42:26 -0500 Message-ID: <4531-434B1882-1048@storefull-3253.bay.webtv.net> References: Jim wrote: "What kind of antenna design could I switch to when I get to close range that would have a narrower beam so I could pinpoint my target?" J. Roy Smith, W6YA described what he called "the simplest of DF loops, with no ambiguity of direction" in CQ magazine`s 1963 "Antenna Roundup". Roy also called ot the "Nobaloop". Roy said it was designed for locating signals on the 10-meter band but has been used with reasonable success on the lower frequency bands. Roy used the loop on 80 transmitter hunts winning first place 15 times when many of his competitors were using identical loops. The loop is about a 1-meter length of 1/4-in. dia.copper tubing (gas line) bent into a neat circle. The two ends are flattened for about half an inch in a plane perpendicular to the radius. Number 28 holes are drilled through the flattened tubing about 1/4-inch from the ends. The loop is attached to a coax receptacle such as Amphenol 83-IR or military type SO 239. One loop end is attached to the outer conductor by a 6-32 screw through one of the four holes. The other loop end is placed over the receptacle`s center conductor lug and soldered well. The small loop gives a figure-8 response in the plane of the loop. The attached coax distorts this pattern, adding its vertical response, like a sense antenna. The resulting pattern is a cardiod. Nearby vertical objects may need detuning to avoid interference with the vertical loop. The maximum lobe is about 30-degrees wide. The null is about 5-degrees wide, according to the author. I have not built it but it seems simple, small, and easy to duplicate. Best regards, Richard Harrison, KB5WZI Article: 218372 of rec.radio.amateur.antenna From: "Fred W4JLE" References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> <434cd876.474806555@news.blueyonder.co.uk> Subject: Re: Aluminum tubing? Date: Mon, 10 Oct 2005 22:40:14 -0400 Message-ID: <706af$434b264d$97d558d8$2462@ALLTEL.NET> Let's face it - English is a crazy language. There is no egg in eggplant, nor ham in hamburger; neither apple nor pine in pineapple. English muffins weren't invented in England or French fries in France. Sweetmeats are candies while sweetbreads, which aren't sweet, are meat. We take English for granted. But if we explore its paradoxes, we find that quicksand can work slowly, boxing rings are square and a guinea pig is neither from Guinea nor is it a pig. And why is it that writers write but fingers don't fing, grocers don't groce and hammers don't ham? If the plural of tooth is teeth, why isn't the plural of booth, beeth? One goose, 2 geese. So one moose, 2 meese? One index, 2 indices? Doesn't it seem crazy that you can make amends but not one amend? If you have a bunch of odds and ends and get rid of all but one of them, what do you call it? If teachers taught, why didn't preachers praught? If a vegetarian eats vegetables, what does a humanitarian eat? Sometimes I think all the English speakers should be committed to an asylum for the verbally insane. In what language do people recite at a play and play at a recital? Ship by truck and send cargo by ship? Have noses that run and feet that smell? How can a slim chance and a fat chance be the same, while a wise man and a wise guy are opposites? You have to marvel at the unique lunacy of a language in which your house can burn up as it burns down, in which you fill in a form by filling it out and in which, an alarm goes off by going on. English was invented by people, not computers, and it reflects the creativity of the human race, which, of course, is not a race at all. That is why, when the stars are out, they are visible, but when the lights are out, they are invisible. PS. - Why doesn't "Buick" rhyme with "quick" "Peter" wrote in message news:434cd876.474806555@news.blueyonder.co.uk... > On Sat, 08 Oct 2005 13:33:35 -0400, Amos Keag > wrote: > > >Because it's ALUMINUM!!! > > > >Tyre is an ancient biblical city. Tire is that round thingee between my > >automobile and the road surface. > > > > Tire is what I do very rapidly when listen to a politician spout forth > on the TV ... :-) Article: 218373 of rec.radio.amateur.antenna From: Sluggo Subject: Re: Need RDF Yagi alternative Message-ID: References: Date: Tue, 11 Oct 2005 02:54:41 GMT Sorry I'm too tired to look up a better example, but http://members.aol.com/BmgEngInc/Adcock.html is still pretty good. It's essentially about like the "phased verticals" the other fellow mentioned, in that they both result in a "cardioid" pattern, i.e. a sharp *notch* in the pattern, broadside to the array in this case. That notch will be far sharper than any beamwidth in gain that a Yagi can possibly have, and, a notch is what you want, close-in, rather than overloading your receiver. The one I used was built by another ham, and IIRC the twin-lead between the two vertical elements was some weird, 50 or 75 ohm twinlead, which is going to be hard to find, and it was crossed, as hinted at in the lower diagram in the URL above, but I think it probably just connected to the coax to the rig at that point, rather than any sort of "Combiner Box" like that shown. We used them to DF a guy who was jamming a 2M repeater net every week. We had cheap compasses, like you'd have on a boat, fixed to the broomstick "boom" of the array, and it was suprisingly accurate at to where all the lines intersected over a period of time. Don't know what ever happened; it was coming from inside a secure telco property, so we couldn't do much "up close and personal" and FCC did not show up as they were allegedly scheduled to do the night I was involved. Just surf around for "Adcock" and DF, antenna, whatever, and I'm sure you'll find what you need. The Doppler antenna the other fellow mentioned are spiffy, but I don't know how inexpensively they can be done. Last time I saw one, it was a dedicated, factory built unit... maybe these days it's possible to "power" the logic with a laptop or something.. It'd be very simple to scale a 2m (144-148 MHz) antenna to your band... Good luck.. HTH, 73, Sluggo On Tue, 11 Oct 2005 01:03:34 -0400, "Jim" wrote: >This isn't strictly a Ham question, but I hope you all can help me anyway. > >I am using small transmitters in the 166-167 mhz range in some Box Turtle >research I am doing. My RDF antenna is a 3 element Yagi designed via >Yagicad 4.1 which works pretty well. It has 48db front/back and about 90 >degrees beamwidth in the H pattern. > >This works well for initial locating......usually starting 1500 to 2000 feet >from my transmitter, but the closer I get, the more inaccurate it becomes. > >What kind of antenna design could I switch to when I get to close range that >would have a narrower beam so I could pinpint my target? It would be nice >to have something smaller than my 35" x 21" yagi for close in work, but the >beam width is the primary concern. > >Yagicad doesn't let me design solely on beam width (at least I haven't >figured out how) so is there another way to go on this?? > >Thanks >Jim > Article: 218374 of rec.radio.amateur.antenna From: David Subject: Re: How to model on EZNEC References: <9hh1f.9103$U51.3133@news-server.bigpond.net.au> <7etfk1lpvpspfgi7u6vd8u0bm4kc463i44@4ax.com> <0jw2f.9312$y_1.3496@edtnps89> <8g8lk15u9hecqslo7n3udnr6jjpkbjnl7p@4ax.com> Message-ID: Date: Tue, 11 Oct 2005 03:20:51 GMT Does it matter that the outer sleeve and radiator element are connected together in the model ? The actual antenna only connects the sleeves to earth braid and the centre conductor does not touch anything ? Frank wrote: >>>----------o---------- ---------- >>> dipole extension >>> >>>Do you think it makes sense? It is the only way I could think of modeling >>>it with NEC. >> >>Hi Frank, >> >>No. The extension lies in the null of the dipole. As such, it would >>be no mystery that it has so little influence. >> >>To model it correctly requires some form of cage or skirt of wires as >>Wes has provided in this thread. >> >>73's >>Richard Clark, KB7QHC > > > I did not notice that somebody had attempted what you suggest. I translated > the coordinates into regular NEC2, and it does run. It appears to violate > some NEC2 criteria, but not sure how critical the model is. Obviously I > cannot use the "Minninec" ground, so have substituted an average S/M ground > with the coax end about an inch above the ground. I had assumed the antenna > was for HF, so it is probably impractically high, causing multiple lobing. > A free space model might provide more meaningful results. > > 73, > > Frank > > Article: 218375 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: V/I ratio is forced to Z0 Date: Tue, 11 Oct 2005 08:51:53 +0000 (UTC) Message-ID: References: <+HzH8raNG+RDFAor@ifwtech.co.uk> <1406-43495B8D-905@storefull-3258.bay.webtv.net> "Ian White wrote > Yup. It measures the reflection coefficient of whatever impedance is > connected to the port on the opposite side from the transmitter. ===================================== No, it doesn't. It measures the MAGNITUDE of the reflection coefficient. It discards the information which is contained in the phase angle of the reflection coefficient. As a consequence the only use which can be made of the magnitude is to calculate the SWR on an imaginary 50-ohm line. The SWR can be used to calculate the magnitude of the reflection coefficient. --- Reg. Article: 218376 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: V/I ratio is forced to Z0 Message-ID: References: <+HzH8raNG+RDFAor@ifwtech.co.uk> <1406-43495B8D-905@storefull-3258.bay.webtv.net> Date: Tue, 11 Oct 2005 10:48:57 GMT On Tue, 11 Oct 2005 10:43:00 +0100, Ian White G/GM3SEK wrote: >Reg Edwards wrote: >> >>"Ian White wrote >>> Yup. It measures the reflection coefficient of whatever impedance is >>> connected to the port on the opposite side from the transmitter. >> >>===================================== >>No, it doesn't. >> >>It measures the MAGNITUDE of the reflection coefficient. It discards >>the information which is contained in the phase angle of the >>reflection coefficient. > >Sorry, I left that important word out. > To be picky, in most implementations, its response is a function of the forward or reflected power provided that Zo is real, and the magnitude of the complex reflection coefficient can be calculated from those measurements. Owen -- Article: 218377 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: V/I ratio is forced to Z0 Date: Tue, 11 Oct 2005 11:50:41 +0000 (UTC) Message-ID: References: <+HzH8raNG+RDFAor@ifwtech.co.uk> <1406-43495B8D-905@storefull-3258.bay.webtv.net> "Owen Duffy" wrote > To be picky, in most implementations, its response is a function of > the forward or reflected power provided that Zo is real, and the > magnitude of the complex reflection coefficient can be calculated from > those measurements. > ================================ Owen, Forward and especially reflected power are even more imaginary than the SWR on a non-existent 50-ohm line. The only use for forward and reflected power is to calculate the magnitude of the reflection coefficient. And the only use for the reflection coefficient is to calculate the imaginary SWR. And the only use . . . . . I understand meter manufacturers provide graphs, which, if you don't know how to use a pocket calculator, will do the calculations for you. But you will still go round in circles. ---- Reg. Article: 218378 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: <+HzH8raNG+RDFAor@ifwtech.co.uk> <1406-43495B8D-905@storefull-3258.bay.webtv.net> Message-ID: Date: Tue, 11 Oct 2005 15:37:51 GMT Reg Edwards wrote: > It measures the MAGNITUDE of the reflection coefficient. It discards > the information which is contained in the phase angle of the > reflection coefficient. As a consequence the only use which can be > made of the magnitude is to calculate the SWR on an imaginary 50-ohm > line. Reg, I dug up some calculations from sci.physics.electromag >from about a year ago that indicate one foot of 50 ohm coax on each side of the Bird is enough to make the line real, i.e. not imaginary, and that's a conservative estimate. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218379 of rec.radio.amateur.antenna Message-ID: <3130303038373835434966E877@zetnet.co.uk> Date: Sun, 9 Oct 2005 18:52:24 +0100 From: Dave Piggin Subject: Re: Aluminum tubing? References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> > Also, why do we say tube rather than valve? Because a tube allows a substance through it without restriction, a valve is a device for controlling such. Dave Article: 218380 of rec.radio.amateur.antenna From: "PeteDBNZA" Subject: Re: Aluminum tubing? Date: Tue, 11 Oct 2005 17:50:28 +0200 Message-ID: References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> <3130303038373835434966E877@zetnet.co.uk> OK. So a linear amp would be built with tubes to allow full flow of signal without restriction, while an audio amp might be built with valves, because we would want to control (restrict) the audio volume. :) This thread seems to have a life of its own. From ally to this! Amazing! -- Pete . . ZS5ACT http://www.electronic-ideas.com/zs5act/ ------ Reply Separator ------ "Dave Piggin" wrote in message news:3130303038373835434966E877@zetnet.co.uk... > >> Also, why do we say tube rather than valve? > > Because a tube allows a substance through it without restriction, a > valve is a device for controlling such. > Dave Article: 218381 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: <+HzH8raNG+RDFAor@ifwtech.co.uk> <1406-43495B8D-905@storefull-3258.bay.webtv.net> Message-ID: Date: Tue, 11 Oct 2005 15:59:41 GMT Reg Edwards wrote: > Forward and especially reflected power are even more imaginary than > the SWR on a non-existent 50-ohm line. My old Heathkit HM-15 SWR meter samples the peak forward and reflected currents. A pot is used to set the meter to full scale using a voltage proportional to the peak forward current. When the voltage proportional to the peak reflected current is then switched into the meter circuit, it reads SWR from the precalibrated scale which is linear with |rho|, i.e. at half-scale, SWR=3 and |rho|=(3-1)/(3+1)=0.5 -- 73, Cecil http://www.qsl.net/w5dxp Article: 218382 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: Message-ID: Date: Tue, 11 Oct 2005 16:09:21 GMT Ian White G/GM3SEK wrote: > All agreed. Along with the math that Cecil has retrieved and quoted > again, everything points towards the distance in question being a > function of coax diameter only; and not wavelength. Please forgive my previous senior moment. It was ~2% of a wavelength at 10 MHz for RG-213. It appears that one foot of coax on each side of a Bird wattmeter is enough to establish Z0 at 50 ohms which forces Vfor/Ifor=Vref/Iref=50, the necessary Bird boundary conditions. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218383 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: <+HzH8raNG+RDFAor@ifwtech.co.uk> <1406-43495B8D-905@storefull-3258.bay.webtv.net> <9nlnk1tjcupna1oovg12ofvur7hfmrj7jq@4ax.com> Message-ID: Date: Tue, 11 Oct 2005 16:37:42 GMT Richard Clark wrote: > That is to say, this "mathematical" distinction that some rely on to > differentiate their arguments has not got one scintilla of difference > over any other method. I must have a dozen equations for SWR, all mathematically consistent with each other. A lot of the math is performed by simply calibrating a meter face. For instance, given a linear meter reading for |rho| with full-scale equal to 1.0, SWR values can be applied to the meter face with 3.0 at half-scale. (Ever notice how many SWR meters have 3.0 at half scale?) -- 73, Cecil http://www.qsl.net/w5dxp Article: 218384 of rec.radio.amateur.antenna From: Bill Turner Subject: Re: Aluminum tubing? Date: Tue, 11 Oct 2005 09:29:57 -0700 Message-ID: References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> <434cd876.474806555@news.blueyonder.co.uk> <706af$434b264d$97d558d8$2462@ALLTEL.NET> On Mon, 10 Oct 2005 22:40:14 -0400, "Fred W4JLE" wrote: >English was invented by people, not computers, and it reflects the >creativity of the human race, which, of course, is not a race at all. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ English is long overdue for an overhaul. Countless hours are spent by schoolchildren learning all the bizarre exceptions to the "rules", which aren't really rules at all. What a waste of time! I would like to see a commission established to reform spelling, to begin with, and if successful, work on grammar. I love the English language, but the time has come. 73, Bill W6WRT Article: 218385 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: <+HzH8raNG+RDFAor@ifwtech.co.uk> <1406-43495B8D-905@storefull-3258.bay.webtv.net> Message-ID: Date: Tue, 11 Oct 2005 16:57:51 GMT Richard Clark wrote: > On Tue, 11 Oct 2005 15:37:51 GMT, Cecil Moore wrote: >>I dug up some calculations from sci.physics.electromag > > which you recite here; then in sci.physics.electromag you can quote > their use by authorities (sic both times) in > rec.radio.amateur.antenna.... > > This appeal is called a circle of friendship - not evidence. Actually, it is called an argumentum ad verecundiam, an appeal to authority - a technical authority in this case. I don't know Kevin G. Rhodes at Dartmouth. He merely answered my question on s.p.e. that didn't find an answer on this newsgroup. Exactly what did you find technically wrong with the following evidence? ****Quote**** Newsgroups: sci.physics.electromag From: "Kevin G. Rhoads" Date: Tue, 07 Oct 2003 12:49:14 -0400 Subject: Re: Transmission Line Question For 10 MHz I would expect that all other modes would be non-propagating (i.e., evanescent) even though RG-213 is a large coax (improved RG-8 apparently). The speed of propagation is listed as 66%, so the nominal wavelength is 3/2 times the free space wavelength for the TEM mode. 3/2 x 30m = 45m, which implies the decay rate in space for non-TEM modes is going to be large as the cable diameter is .405" (jacket) which implies the spacing from inner to outer conductors will be less than .203". For order of magnitude estimate, assuming the lowest non-TEM mode can be approximated using a characteristic equation that really is only applicable in Cartesian geometries: (1/45m)**2 = (1/.203")**2 + kz**2 Clearly, kz must be imaginary to make this work. thus an evanescant, non-propagating wave: kz**2 = (1/45m)**2 - (1/.203")**2 To the accuracy used to date, the first term on the right is negligible, so the decay rate, alpha, can be estimated: alpha**2 = - (kz)**2 = (1/2.03")**2 Or, the lowest order undesired mode should reduce intensity by a factor of 1/e (0.37) in about 2.03"; power will reduce by that factor squared in the same distance (.135). In about four inches, undesired mode power is down to about 0.018, in six inches, .00248, and after a foot, 6.14x10-6 You should double check my algebra, but I think the estimate is reasonable. To put it into other terms, since the wavelength in the coax dielectric is 45m and the conductor to conductor spacing is about 2", any non-TEM mode will suffer attenuation in E-field intensity with a space-rate constant rounghly equal to the conductor to conductor spacing. INtensity drops by 1/e = 1/2.71828 every 2 inches. Power availalbe drops faster, being square of intensity. So unless almost all the power diverts into an undesireable mode (by a factor of more than a million to one), one foot of cable should see pure TEM at the end. ***End Quote*** -- 73, Cecil http://www.qsl.net/w5dxp Article: 218386 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: <+HzH8raNG+RDFAor@ifwtech.co.uk> <1406-43495B8D-905@storefull-3258.bay.webtv.net> <9nlnk1tjcupna1oovg12ofvur7hfmrj7jq@4ax.com> <32rnk11b8e9dv0m473ugqhba1sft38n4b9@4ax.com> Message-ID: Date: Tue, 11 Oct 2005 17:11:15 GMT Richard Clark wrote: > Cecil Moore wrote: >>Ever notice how many SWR meters have 3.0 at half scale? > > Amateur grade - 1 in 4; Even my double-needle meters have 3:1 as a vertical line at the center. All of my single-needle SWR meters have 3.0 at half scale since they are actually reading |rho|. Check out this humoungous one. Click on the small meter picture for a full-size picture. http://www.mfjenterprises.com/products.php?prodid=MFJ-868 -- 73, Cecil http://www.qsl.net/w5dxp Article: 218387 of rec.radio.amateur.antenna From: Jim Kelley Subject: Re: V/I ratio is forced to Z0 Date: Tue, 11 Oct 2005 10:15:53 -0700 Message-ID: References: <+HzH8raNG+RDFAor@ifwtech.co.uk> <1406-43495B8D-905@storefull-3258.bay.webtv.net> But how does the attenuation length of non-TEM modes relate to the Zo of a transmission line? ac6xg Cecil Moore wrote: > Actually, it is called an argumentum ad verecundiam, an appeal > to authority - a technical authority in this case. I don't know > Kevin G. Rhodes at Dartmouth. He merely answered my question on > s.p.e. that didn't find an answer on this newsgroup. Exactly what > did you find technically wrong with the following evidence? > > ****Quote**** > Newsgroups: sci.physics.electromag > From: "Kevin G. Rhoads" > Date: Tue, 07 Oct 2003 12:49:14 -0400 > Subject: Re: Transmission Line Question > > For 10 MHz I would expect that all other modes > would be non-propagating (i.e., evanescent) even though RG-213 > is a large coax (improved RG-8 apparently). The speed of propagation > is listed as 66%, so the nominal wavelength is 3/2 times the free > space wavelength for the TEM mode. 3/2 x 30m = 45m, which implies > the decay rate in space for non-TEM modes is going to be large > as the cable diameter is .405" (jacket) which implies the > spacing from inner to outer conductors will be less than .203". > For order of magnitude estimate, assuming the lowest non-TEM mode > can be approximated using a characteristic equation that really > is only applicable in Cartesian geometries: > (1/45m)**2 = (1/.203")**2 + kz**2 > Clearly, kz must be imaginary to make this work. thus an > evanescant, non-propagating wave: > kz**2 = (1/45m)**2 - (1/.203")**2 > To the accuracy used to date, the first term on the right > is negligible, so the decay rate, alpha, can be estimated: > alpha**2 = - (kz)**2 = (1/2.03")**2 > Or, the lowest order undesired mode should reduce intensity > by a factor of 1/e (0.37) in about 2.03"; power will reduce > by that factor squared in the same distance (.135). In > about four inches, undesired mode power is down to about > 0.018, in six inches, .00248, and after a foot, 6.14x10-6 > > You should double check my algebra, but I think the estimate > is reasonable. To put it into other terms, since the wavelength > in the coax dielectric is 45m and the conductor to conductor > spacing is about 2", any non-TEM mode will suffer attenuation > in E-field intensity with a space-rate constant rounghly > equal to the conductor to conductor spacing. INtensity > drops by 1/e = 1/2.71828 every 2 inches. Power availalbe > drops faster, being square of intensity. > > So unless almost all the power diverts into an undesireable > mode (by a factor of more than a million to one), one foot > of cable should see pure TEM at the end. > ***End Quote*** Article: 218388 of rec.radio.amateur.antenna From: Ed Bailen Subject: Re: Dipole on a hill? Farther from ground or farther up the hill? Date: Tue, 11 Oct 2005 12:21:32 -0500 Message-ID: References: On Mon, 03 Oct 2005 20:25:34 GMT, Lance Orner wrote: >Just getting back into HF, and I'm trying to get an antenna up on my >small lot which backs up to a hillside. There are two locations >available without erecting more infrastructure. One would be about 20 >feet up at the base of the hill, and the other is about 50 feet up the >hill, but only 10 feet off the ground. > >So the question: Is it more important to have the antenna farther >from ground, or father up the hill but closer to ground? > >In the future, I'd love to put a tall antenna at the tallest part of >the hill, but I'm looking for something temporary right now. > >Thanks. FWIW, the centers of my dipoles are near the top of a 40' tower near the top of a hill behind my house. The ends of the 160m dipole are about 8' off the ground, but about 60' to 80' below the base of the tower. It works, but I don't have anything to compare it to. It's the only mounting option I have unless I want to get a couple of push-up masts to elevate the ends of the dipoles more. (They would still end up below the base of the tower. 73, Ed Article: 218389 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: <+HzH8raNG+RDFAor@ifwtech.co.uk> <1406-43495B8D-905@storefull-3258.bay.webtv.net> Message-ID: Date: Tue, 11 Oct 2005 17:44:09 GMT Jim Kelley wrote: > But how does the attenuation length of non-TEM modes relate to the Zo of > a transmission line? And to whether it's parallel or coaxial? Good question. Kevin Rhodes' email address can be had from Google. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218390 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: <+HzH8raNG+RDFAor@ifwtech.co.uk> <1406-43495B8D-905@storefull-3258.bay.webtv.net> Message-ID: Date: Tue, 11 Oct 2005 17:45:51 GMT Richard Clark wrote: > Name dropping is not an appeal to authority, nor are third hand > quotes. Exactly what did you find technically wrong with that third hand quote? -- 73, Cecil http://www.qsl.net/w5dxp Article: 218391 of rec.radio.amateur.antenna From: "Fred W4JLE" References: <+HzH8raNG+RDFAor@ifwtech.co.uk> <1406-43495B8D-905@storefull-3258.bay.webtv.net> Subject: Re: V/I ratio is forced to Z0 Date: Tue, 11 Oct 2005 14:09:03 -0400 Message-ID: <44eba$434bffff$97d558d8$29118@ALLTEL.NET> I would then assume you disregard anything written in books as it falls in the same category. "Richard Clark" wrote in message news:bbtnk15blbvsr22vcegl56pcpm4qebmvid@4ax.com... > On Tue, 11 Oct 2005 16:57:51 GMT, Cecil Moore < > > Name dropping is not an appeal to authority, nor are third hand > quotes. Article: 218392 of rec.radio.amateur.antenna From: "Roger Conroy" Subject: Re: Aluminum tubing? Date: Tue, 11 Oct 2005 20:30:20 +0200 Message-ID: References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> "Bruce" wrote in message news:Xns96EA4DD152A15xxxyyyzzz@216.77.188.18... > kashe@sonic.net wrote in > news:nfvgk11r9qfobufnj3lsbl23jn01tqv8k4@4ax.com: > >> On Sat, 08 Oct 2005 14:43:58 -0500, Bob Bob wrote: >> >>>And being even further OT >>> >>>Brings further ambiguity to the term "retired" as well. (Like my 65 yo >>>father just had a wheel transplant) >>> >>>Since I live in W5... How does one say/spell Titanium/Titanum? >>> >>>I look at signs on the side of the road "Hiway" and cant for the life >>>of me work out what that means... >>> >>>Peter, its actually said in the US how it looks. >> >> Which is why we pronounce extraordinary with five or six >> syllables instead of two. >> >>> This gets real >>>confusing for me! (Along with driving on the WRONG side of the road! >>>) >>> >>>Cheers Bob W5/VK2YQA East Texas >>>(past the langauge test - can say "Y'all" easily) >>> >>>John N9JG wrote: >>> >>>>>Why do you guys in the US always omit the "i" in aluminium ? > > > You mean the second "i"? Probably because we spell it correctly: Aluminum. > ;~) But you do it ONLY to Alumin(i)um. What about Lithium, Barium, Chromium, Ruthenium, Titanium, Uranium, and so on......? > I suppose we could also ask why you need to pronounce the first "u" hard. Most South Africans don't. 73 Roger ZR3RC Article: 218393 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: How to model on EZNEC References: <9hh1f.9103$U51.3133@news-server.bigpond.net.au> <7etfk1lpvpspfgi7u6vd8u0bm4kc463i44@4ax.com> <0jw2f.9312$y_1.3496@edtnps89> <8g8lk15u9hecqslo7n3udnr6jjpkbjnl7p@4ax.com> <7gU2f.9979$y_1.4296@edtnps89> Message-ID: Date: Tue, 11 Oct 2005 19:33:51 GMT Frank wrote: > ... I prefer to enter in basic code, > which is apparently not available in EZNEC. EZNEC data can be entered from an ASCII file. I regularly generate ASCII files using MS Professional Basic for entry into EZNEC. Here's a quote from the EZNEC help file: "Wire coordinates can be imported from an ASCII file in a simple format, either replacing or adding to the existing model. This can be used to import coordinates from another program." -- 73, Cecil http://www.qsl.net/w5dxp Article: 218394 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: V/I ratio is forced to Z0 Date: Tue, 11 Oct 2005 20:01:45 +0000 (UTC) Message-ID: References: <+HzH8raNG+RDFAor@ifwtech.co.uk> <1406-43495B8D-905@storefull-3258.bay.webtv.net> "Cecil Moore" wrote > Reg, I dug up some calculations from sci.physics.electromag > from about a year ago that indicate one foot of 50 ohm coax > on each side of the Bird is enough to make the line real, > i.e. not imaginary, and that's a conservative estimate. =========================================== Cec, I still have a 30-watt, 160m, portable transceiver which I made about 20 years back. It's in an aluminium attache case and still works. In my travelling days I used to toss a wire out of the hotel bedroom window. Lift the lid and on the front panel is a 1.5"-square moving-coil meter. It is used as a TLI on transmit and as an S-meter on receive. The meter scale is calibrated 0-500 microamps. But my imagination doesn't fool ME. On receive, when the meter indicates 50% of full-scale deflection I know that the meter is actually measuring 250 microamps. And on transmit, when the meter indicates 90% of full scale deflection I know that the meter is actually measuring 450 microamps. Let this little anecdote be a friendly warning to they who use meters with a 0 to infinity SWR scale, or scaled in terms of forward and reverse power. ---- Reg, G4FGQ. Article: 218395 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: V/I ratio is forced to Z0 Date: Tue, 11 Oct 2005 20:19:35 +0000 (UTC) Message-ID: References: <+HzH8raNG+RDFAor@ifwtech.co.uk> <1406-43495B8D-905@storefull-3258.bay.webtv.net> "Cecil Moore" wrote > Reg, I dug up some calculations from sci.physics.electromag > from about a year ago that indicate one foot of 50 ohm coax > on each side of the Bird is enough to make the line real, > i.e. not imaginary, and that's a conservative estimate. ============================================ Cec, you forgot to say sci.physics.electromag were working at 500 MHz and above. The one and only so-called SWR meter I have stops at 30 MHz. ;o) ---- Reg. Article: 218396 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: V/I ratio is forced to Z0 Message-ID: References: <+HzH8raNG+RDFAor@ifwtech.co.uk> <1406-43495B8D-905@storefull-3258.bay.webtv.net> Date: Tue, 11 Oct 2005 20:53:13 GMT On Tue, 11 Oct 2005 16:57:51 GMT, Cecil Moore wrote: >****Quote**** >Newsgroups: sci.physics.electromag >From: "Kevin G. Rhoads" >Date: Tue, 07 Oct 2003 12:49:14 -0400 >Subject: Re: Transmission Line Question ... >So unless almost all the power diverts into an undesireable >mode (by a factor of more than a million to one), one foot >of cable should see pure TEM at the end. >***End Quote*** But Cecil, nowhere in the analysis you quoted does it estimate how much power is diverted from the dominant mode at the discontinuity. If the explanation of the discontinuity is that some power is converted from dominant propagation mode to another mode, and that those other modes are evanescent, it seems that this analysis of the impact of the discontinuity considers only estimating the decay rate of the evanescent modes without estimation of the relative magnitude of the power diverted to those modes in the first place. Owen -- Article: 218397 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: <+HzH8raNG+RDFAor@ifwtech.co.uk> <1406-43495B8D-905@storefull-3258.bay.webtv.net> Message-ID: Date: Tue, 11 Oct 2005 21:12:21 GMT Reg Edwards wrote: > Let this little anecdote be a friendly warning to they who use meters > with a 0 to infinity SWR scale, or scaled in terms of forward and > reverse power. If the scale were linearly calibrated for |rho| = 0 to 1, would you still be objecting? SWR = (1+|rho|)/(1-|rho|) for 0 <= |rho| <= 1 When SWR = infinity, it doesn't mean infinite current through the meter. It just means that Vref = Vfor where |Vref|/|Vfor| = |rho|. My Heathkit HM-15 allows for full scale to equal Vfor. Then Vref is applied. The scale is a linear indication for |rho|. The corresponding SWR scale just follows the above equation. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218398 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: <+HzH8raNG+RDFAor@ifwtech.co.uk> <1406-43495B8D-905@storefull-3258.bay.webtv.net> Message-ID: Date: Tue, 11 Oct 2005 21:15:22 GMT Reg Edwards wrote: > Cec, you forgot to say sci.physics.electromag were working at 500 MHz > and above. Not true, Reg. My question was specified using RG-213 at 10 MHz. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218399 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: Message-ID: Date: Tue, 11 Oct 2005 21:25:53 GMT Ian White G/GM3SEK wrote: > The Bird doesn't require any upstream and downstream boundary > conditions. When Bird requires a 50 ohm environment, they are requiring 50 ohm boundary conditions for the reading to be valid. If you install the Bird in a 450 ohm environment on both sides of the wattmeter, for instance, it will NOT read a valid forward power and reflected power. In a matched-line 450 ohm environment with absolutely zero reflected power, the Bird will indicate an SWR of 9:1, a |rho| of 0.8 and a ratio of reflected power to forward power of 0.64 even when the reflected power is zero. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218400 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: Cheap interface for your Icom Date: Tue, 11 Oct 2005 15:41:11 -0500 Message-ID: References: Fred, It's been a while since I looked into the RS level converters. Another glance yields no serious shortcoming. The only thing I can see is that a lap-top with 5 volt serial voltages may have problems. However, if it works for you... I roll my own with transistors. 73, Steve, K,9.D;C'I "Fred W4JLE" wrote in message news:fcb8$434586ec$97d558d8$29619@ALLTEL.NET... > I wanted to use Ham Radio Deluxe with my Icom radio. It requires an CI-V > interface. Being the cheapskate that I am, I checked the internet for "roll > your own" information. > > What I found looked really familiar, turns out it is identical to an > interface I built to program my Radio Shack Pro 95 scanner. Plugged it in > and it worked just great. > > This means you can purchase a RadioShack 20-289 cable for $24.99 and replace > the high dollar CI-V if you choose not to build your own. > > Article: 218401 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: <+HzH8raNG+RDFAor@ifwtech.co.uk> <1406-43495B8D-905@storefull-3258.bay.webtv.net> Message-ID: Date: Tue, 11 Oct 2005 21:33:20 GMT Owen Duffy wrote: > If the explanation of the discontinuity is that some power is > converted from dominant propagation mode to another mode, and that > those other modes are evanescent, it seems that this analysis of the > impact of the discontinuity considers only estimating the decay rate > of the evanescent modes without estimation of the relative magnitude > of the power diverted to those modes in the first place. I've always had a rule of thumb that 100 times the diameter of the coax was enough length to 99% establish the TEM mode so Kevin's explaination made sense to me. Apparently, you are not satisfied with Kevin's explaination. Kevin Rhodes email address is available on Google. The reason not to publish it here is to avoid spaming his email account. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218402 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Transmitter ALC Message-ID: References: <6shgk11bict76alt5j6gr0d0trekiu2gal@4ax.com> <1129064635.814589.146980@g49g2000cwa.googlegroups.com> Date: Tue, 11 Oct 2005 21:33:18 GMT On 11 Oct 2005 14:03:55 -0700, nm5k@wt.net wrote: >>A radio that needs 16A in operation, but 25 during tune is a >>pain in the butt on a nominal 20A power supply with over current >>protection that kicks in above 22A! > >Myself, I never tune using full power. With my 706g, I either >put it on "AM", or reduce the drive to a pretty low level. I did the >same on my 730. Only with a good match would I ever test full >power output. I do the same with my tube TS-830.. heck, actually >any transmitter... :/ Quite wise. Nevertheless, large currents are drawn by some radios in low power. For example, I owned a Alinco DX70-TH and their EDX-2 autotuner. When it autotuned, the tx power was reduced to about 10W out, but it still drew in excess of 20A tuning into some loads on some frequencies... which would trip the overcurrent protection in one of my power supplies, so it was unusable on that power supply. People do rough tune radios on full power, and I, like yourself, question the wisdom of that practice. I designed a device to make manual low power tuning with an IC706x more convenient ( http://www.vk1od.net/IC706TuneMate/IC706TuneMate.htm ). It has been interesting that almost all of the feedback that I have received on the article is from screwdriver antenna users who insist that it is absolutely unecessary, they tune their screwdriver for maximum RF Po indication on the IC706x meter using full power in RTTY mode. (Achieving high RF Po indication depends indirectly on low VSWR because of the PA load protection scheme.) Owen -- Article: 218403 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Transmitter ALC References: <6shgk11bict76alt5j6gr0d0trekiu2gal@4ax.com> <1129064635.814589.146980@g49g2000cwa.googlegroups.com> Message-ID: <4eW2f.839$BZ5.587@newssvr13.news.prodigy.com> Date: Tue, 11 Oct 2005 21:34:56 GMT nm5k@wt.net wrote: > Myself, I never tune using full power. Don't trust the foldback circuitry or just being polite? -- 73, Cecil http://www.qsl.net/w5dxp Article: 218404 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: V/I ratio is forced to Z0 Message-ID: References: <+HzH8raNG+RDFAor@ifwtech.co.uk> <1406-43495B8D-905@storefull-3258.bay.webtv.net> Date: Tue, 11 Oct 2005 21:36:00 GMT On Tue, 11 Oct 2005 21:15:22 GMT, Cecil Moore wrote: >Not true, Reg. My question was specified using RG-213 at 10 MHz. True enough, but in the context of the question as to whether the Bird 43 reads sufficiently accurately, the transmission line on which one is interested in the decay of the evanescent modes is the Bird Thruline coupler section, not Rg-213 or any other cable that might be attached to the Bird. Owen -- Article: 218405 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: V/I ratio is forced to Z0 Message-ID: References: Date: Tue, 11 Oct 2005 21:53:24 GMT On Tue, 11 Oct 2005 21:25:53 GMT, Cecil Moore wrote: >Ian White G/GM3SEK wrote: >> The Bird doesn't require any upstream and downstream boundary >> conditions. > >When Bird requires a 50 ohm environment, they are requiring >50 ohm boundary conditions for the reading to be valid. If >you install the Bird in a 450 ohm environment on both sides >of the wattmeter, for instance, it will NOT read a valid forward >power and reflected power. In a matched-line 450 ohm environment >with absolutely zero reflected power, the Bird will indicate an >SWR of 9:1, a |rho| of 0.8 and a ratio of reflected power to >forward power of 0.64 even when the reflected power is zero. (I am assuming your 450 ohm line to be an unbalanced line, impractical as that is, but the issues of balance to unbalanced transition are just noise to the discussion.) Is this about whether the Bird readings are correct for the conditions on the Bird Thruline, or whether the meter readings are extensible to the adjacent transmission line without further interpretation / modelling? The Bird readings should be correct for the conditions on the Bird Thruline. You can safely extend those measurements literally to the adjacent line where the adjacent line is the same as the Bird Thruline and of negligible loss. In other cases, knowing the line parameters, you may be able to use the measurements to some extent to calculating some conditions on the other line. Though the Bird readings in your example for Forward and Reflect Power cannot be assumed valid for the adjacent line, the net power should be correct. I don't think anyone is suggesting that the Bird could be used in a general sense to estimate the VSWR on your 450 ohm line. Owen -- Article: 218406 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: Transmitter ALC Date: Tue, 11 Oct 2005 16:32:59 -0500 Message-ID: References: <6shgk11bict76alt5j6gr0d0trekiu2gal@4ax.com> Owen, You have obviously have extensive knowledge and familiarity with some equipment on this subject. I haven't studied this aspect of the radios I have yet, but offer the following from my design experience. There are several relatively independent considerations which have been mentioned in this thread and I hope this clears up any confusion about which is doing what. My understanding of the true purpose of (what we call) ALC is to prevent distortion in the final amplifier and the resulting "splatter" it causes, while allowing the maximum power out. As you so correctly point out, this originated in the linear amplifiers of old. Distortion at this point causes increased intermodulation (mixing) of the desired signal components and the resulting products appear out of the normal bandwidth = "splatter". There is always SOME of this going on, but as long as it is below about -30 dBc this is considered acceptable. Because there is no Grid current to sense in solid state amplifiers, some other method of detecting the onset of distorting is required. Not knowing what _IS_ done, I can only speculate that knowing the highest level of output power which causes only a small, allowable increase in distortion, an output level detector can be designed which begins to provide feed back which cuts drive when this point is reached; thus paralleling the function of the grid current detection method of old. Because this is an instantaneous feedback system with a relatively high gain, the feed back voltage will exhibit a considerable rise as the device is driven closer and closer to the undesirable point. This must be what we are looking at that is called ALC on the front of the radio. As long as the level of this signal is within the manufacturer's limits, the distortion is limited to the specification and you are assured of the highest power with in-spec distortion. With solid state comes other considerations which are actually separate >from the distortion issue although from a circuitry standpoint they may seem identical. Because these devices have been and are still somewhat sensitive to mis-treatment and can be destroyed instantaneously, various methods are available to help save the devices. However, had they been easily available in tube days, they would have been equally applicable. Sensing and placing a limit on collector/drain current is one method. Some load conditions can cause excessive current resulting in device destruction, so sensing over-current electronically and reducing drive can prevent this. With the advent of simple reverse power sensing circuitry, another fault detection scheme can be used to reduce drive and protect the final power device. Sensing SWR and reducing drive can prevent high device current and destruction, as well. Heat rise can also destroy the device, so sensing device temp and reducing drive controls this also. Because a design has one or more of these, the identity of each could be confused by combining the feedback signal and calling it only "ALC" when in actuality, there are two or more protection schemes present along with the (distortion limiting) ALC. 73, Steve, K'9;D.C,I snipping quite a bit: "Owen Duffy" wrote in message news:o10jk19dgli473a21b098qotl1940t4rdf@4ax.com... > On Sun, 9 Oct 2005 20:11:09 +0000 (UTC), "Reg Edwards" > wrote: > > > > >"Owen Duffy" wrote various ways and means of automatically > >controlling the power output of transmitters. Thanks very much. > > > >Presumably control is needed to limit the power dissipated ... > > Another method of PA protection is thermal protection of the PA... > > > > >In my Icom 735 transceiver the first control requirement appears to be > >met by by placing a limit on the DC collector current or power input. > > You are right, some radios do incorporate over-current protection ... > > Whilst probably intended for PA protection, it has the great benefit > that the radio is less likely to draw excessive current while > adjusting an ATU, ... > > As I described, and for example, from the IC706IIG service manual: > "The reflected wave signal appears ...the antenna is mismatched. The > ...signal level is detected ...and > applied to the ALC circuit as the reference voltage." .... > > Owen > -- Article: 218407 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Transmitter ALC Message-ID: References: <6shgk11bict76alt5j6gr0d0trekiu2gal@4ax.com> Date: Tue, 11 Oct 2005 22:46:36 GMT On Tue, 11 Oct 2005 16:32:59 -0500, "Steve Nosko" wrote: > Because a design has one or more of these, the identity of each could be >confused by combining the feedback signal and calling it only "ALC" when in >actuality, there are two or more protection schemes present along with the >(distortion limiting) ALC. Yes Steve, once you have the gain control mechanism, it becomes the obvious control point for various over-x closed loop control systems. But you are right that the highest priority function is for limitation of distortion due to exessive signal (for the current conditions), and it is that loop that has the most onerous dynamic performance requirements (eg fast attack) for it to perform the intended fuction well. Unfortunately, there is a growing common belief that unless the ALC meter is high upscale, then the rig isn't being talked up enough (the dumbing down of ham radio). There seems a common ignorance that most ALC detectors have a threshold (usually the rated PEP for solid state PAs), and that the slightest deflection of the indicator means that some peak signal has reached that threshold, further deflection causes greater gain reduction in the IF stages, causing the ALC to act more and more as a compressor where overdrive of the PA is likely to occur on transients during ALC attack time. Exceeding the red line, even for occasional transients, is to exceed the capability of the ALC to contain PA distortion due to overload. My thought is that if you want audio compression, use a speech processor, not the ALC. Mentioning speech processors. A correctly adjusted speech processor is proably better protection against overdrive than depending on ALC alone. The peaks are contained (clipped) and the distortion products filtered off, before getting near the PA which does not have effective post filtering for clipping distorion. Owen -- Article: 218408 of rec.radio.amateur.antenna From: David Subject: EZNEC model of sleeve antenna Message-ID: Date: Tue, 11 Oct 2005 23:15:51 GMT Thank you to whoever provided the coordinates for the model of this antenna. I wrote them down and entered them when I saw them in your posting but the original email has been automatically removed from the folder in my email client. There has been a lot of discussion and side issues raised from my original post but I am grateful for you taking the time to provide the information for me. I am a novice with regard to antenna theory and have no previous experience with antenna modeling. Your post has given me a good starting point. I entered the coordinates and (beside initially selecting wavelengths instead of inches) the model ran fine. I was then able to scale it up to the frequency of interest (920 MHz) and now I am playing with the sleeve diameter, sleeve length and radiator length to observe how these are effecting radiation pattern and SWR. There was also mention of a book regarding basic antenna modeling, my next step will be to purchase a good book to help me understand the process and limitations etc. Thanks again Regards David Huisman Article: 218409 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: Need RDF Yagi alternative References: <20rq13-5m2.ln1@p400bob.personal.cox.net> <13eab$434affc3$d80c392d$10862@NAXS.COM> Message-ID: Date: Tue, 11 Oct 2005 18:31:07 -0500 Since Bruce hasnt responded A cavity filter is a very narrow band filter usually of silvered copper pipe construction. At 160MHz its going to be about 18" long and maybe 3" dia. You might be able to get away with a helical filter instead. Thats a copper/silverplated coil inside a silvered/copper box. I'd suggest three coupled together if you were serious. They could then be in a (say) 4" x 2" x 2" box. In this case the use is as a tuned TRF receiver connected direct to a RF measuring device. When you are close you simply watch the meter and walk towards where it gets stronger and away from where it is weaker! I'll comment on your other post in a moment. Cheers Bob Jim wrote: > > I am not familiar with a "cavity filter". I'll do some Googling on that. > Can you fill me in on it's use? Article: 218410 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: Need RDF Yagi alternative References: <20rq13-5m2.ln1@p400bob.personal.cox.net> <650c$434afc93$d80c392d$667@NAXS.COM> Message-ID: Date: Tue, 11 Oct 2005 19:00:29 -0500 Hi again Jim I'd suspect you need an attenuator of maybe 60dB in 6dB steps! I cant see the 10dB variable one as being useful. Of course at 50dB or more coax leakage might be an issue! The other researcher you mentioned most likely dropped to signal strength only mode when they got close. Antenna directivity up close in my view isnt a viable way of doing it. As a rough guide you get a 6dB change in signal power everytime you double or halve the distance. This means that if you maximum signal measured distance is maybe 6ft and it must work out to 2000 yards then you have to allow for 60dB of measurement range. This is further complicated by the turtle antenna being at ground level, in fact in the mud and dirt. I dont know what that loss represents but I'd add 30dB to be sure. Your whole system then must have some method of measuring over that range of 90 odd dB and have useful directional nulls etc doing so. This is where the big step attenuator and antenna changing/removal help. Should the antenna work okay? I guess the question is did you include the ground in the modelling? Obviously you'd get some major sky direction lobes/response from ground reflection but the worry is how it affects overall directivity. My gut feel is that the F/B would be markedly different and nowhere near the 48dB. At 1M above ground there may be sufficient detuning of elements to widen the frontal lobe but I doubt it would be a huge excursion. Do you find the null is much sharper than the frontal lobe? The bottom line though is that in your application it isnt as critical as someone (like amateurs) trying for maximum performance. This means I should stop complaining! Okay on the screening. Well as I mentioned the test is to plug a 50 ohm load in the antenna socket and see if it responds at a distance of say 5ft. If it doesnt then dont worry about screening. If it does it depends on how much and then whether things like coax leakage have to be factored in. I'll stop ranting/waffling on now..! Cheers Bob Jim wrote: > True, I haven't thought of everything, but I have done this: Article: 218411 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: <+HzH8raNG+RDFAor@ifwtech.co.uk> <1406-43495B8D-905@storefull-3258.bay.webtv.net> Message-ID: Date: Wed, 12 Oct 2005 02:03:10 GMT Owen Duffy wrote: > Cecil Moore wrote: >>Not true, Reg. My question was specified using RG-213 at 10 MHz. > > True enough, but in the context of the question as to whether the Bird > 43 reads sufficiently accurately, the transmission line on which one > is interested in the decay of the evanescent modes is the Bird > Thruline coupler section, not Rg-213 or any other cable that might be > attached to the Bird. I didn't read it that way, Owen. IMO, the real question is: What length of 50 ohm coax needs to be attached to the Bird input and output to ensure that a 50 ohm environment is present? -- 73, Cecil http://www.qsl.net/w5dxp Article: 218412 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: Message-ID: <8b_2f.15566$6e1.12775@newssvr14.news.prodigy.com> Date: Wed, 12 Oct 2005 02:04:52 GMT Owen Duffy wrote: > I don't think anyone is suggesting that the Bird could be used in a > general sense to estimate the VSWR on your 450 ohm line. I thought that was the subject of the discussion. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218413 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: <+HzH8raNG+RDFAor@ifwtech.co.uk> <1406-43495B8D-905@storefull-3258.bay.webtv.net> <44eba$434bffff$97d558d8$29118@ALLTEL.NET> <6kdok15gb0r3ghnn4pdpq7m1o553hvposg@4ax.com> Message-ID: Date: Wed, 12 Oct 2005 02:06:22 GMT Richard Clark wrote: > Certainly anything that is third hand and name dropping - but you > already knew that from my previous posting. It's obvious that you cannot bring yourself to believe that e=mc^2. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218414 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: V/I ratio is forced to Z0 Message-ID: References: <8b_2f.15566$6e1.12775@newssvr14.news.prodigy.com> Date: Wed, 12 Oct 2005 02:13:21 GMT On Wed, 12 Oct 2005 02:04:52 GMT, Cecil Moore wrote: >Owen Duffy wrote: >> I don't think anyone is suggesting that the Bird could be used in a >> general sense to estimate the VSWR on your 450 ohm line. > >I thought that was the subject of the discussion. >From an earlier post: In the case of the Bird 43, I suggest that if had, say, at 1MHz, 75 ohm line and a 75 ohm load on the load side, that the V/I raio for the travelling waves in the region of the sampling element would be so close to 50 ohms as to not materially affect the accuracy of measurements on the 50 ohms coupler section, irrespective of the fact that the sampling element has only 0.02% of a wavelength of 50 ohm line on its load side. (For avoidance of doubt, nothing in the foregoing is to imply the Bird 43 would be directly measuring or indicating the conditions on the 75 ohm line.) Owen -- Article: 218415 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: Message-ID: <1m_2f.15570$6e1.4509@newssvr14.news.prodigy.com> Date: Wed, 12 Oct 2005 02:16:29 GMT Ian White G/GM3SEK wrote: > You have changed the impedance environment to 450 ohms, and that's > fine... but all of the Bird's readings are perfectly correct if the > system reference impedance remains defined at 50 ohms. I have changed the system reference impedance to 450 ohms. Assuming a tube PA with a pi-net output, 50 ohms doesn't exist anywhere anymore. The system reference impedance is no longer 50 ohms so the Bird wattmeter is being abused and misused. You can do the same thing by using a DC voltmeter on an RF voltage or by using a hammer on a screw. If you want to know the SWR on 450 ohm line, use a 450 ohm SWR meter. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218416 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: <8b_2f.15566$6e1.12775@newssvr14.news.prodigy.com> Message-ID: Date: Wed, 12 Oct 2005 02:25:33 GMT Owen Duffy wrote: > In the case of the Bird 43, I suggest that if had, say, at 1MHz, 75 > ohm line and a 75 ohm load on the load side, that the V/I raio for the > travelling waves in the region of the sampling element would be so > close to 50 ohms as to not materially affect the accuracy of > measurements on the 50 ohms coupler section, irrespective of the fact > that the sampling element has only 0.02% of a wavelength of 50 ohm > line on its load side. If there is 75 ohm coax on the input of the Bird, the reflected power reported by the Bird on the coax will be off by an infinite percent. That's pretty inaccurate. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218417 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: V/I ratio is forced to Z0 Message-ID: <6etok1pcelntp3bkj0hrqi0c3an2an2unv@4ax.com> References: <8b_2f.15566$6e1.12775@newssvr14.news.prodigy.com> Date: Wed, 12 Oct 2005 02:41:33 GMT On Wed, 12 Oct 2005 02:25:33 GMT, Cecil Moore wrote: >Owen Duffy wrote: >> In the case of the Bird 43, I suggest that if had, say, at 1MHz, 75 >> ohm line and a 75 ohm load on the load side, that the V/I raio for the >> travelling waves in the region of the sampling element would be so >> close to 50 ohms as to not materially affect the accuracy of >> measurements on the 50 ohms coupler section, irrespective of the fact >> that the sampling element has only 0.02% of a wavelength of 50 ohm >> line on its load side. > >If there is 75 ohm coax on the input of the Bird, the reflected >power reported by the Bird on the coax will be off by an infinite >percent. That's pretty inaccurate. The Bird does not measure or report the conditions on the coax, it measures and reports the conditions in the immediate region of the sampling element which is some 40mm inside the Thruline coupler section. Owen -- Article: 218418 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: <8b_2f.15566$6e1.12775@newssvr14.news.prodigy.com> <6etok1pcelntp3bkj0hrqi0c3an2an2unv@4ax.com> Message-ID: Date: Wed, 12 Oct 2005 04:06:07 GMT Owen Duffy wrote: > The Bird does not measure or report the conditions on the coax, it > measures and reports the conditions in the immediate region of the > sampling element which is some 40mm inside the Thruline coupler > section. I don't know what this argument is all about. Consider the following: XMTR---75 ohm coax---Bird---75 ohm load Are you saying the Bird's placement will result in a reflection coefficient of 0.2? I seriously doubt that is true. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218419 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Aluminum tubing? References: <1128562179_21@isp.n> <1129086831.223288.307380@g44g2000cwa.googlegroups.com> Message-ID: <1003f.475$dO2.207@newssvr29.news.prodigy.net> Date: Wed, 12 Oct 2005 04:09:33 GMT rckchp wrote: > Look here : > http://users.lmi.net/~ryoung/Sonerai/Aircraft_Aluminum_Sources.htm Heck, MFJ is even carrying Hy-gain Aluminum Tubing now in 6' telescoping sections. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218420 of rec.radio.amateur.antenna From: "Asimov" Subject: Re: Aluminum tubing? Message-ID: References: <3130303038373835434966E877@zetnet.co.uk> Date: Wed, 12 Oct 2005 04:11:02 GMT "Dave Piggin" bravely wrote to "All" (09 Oct 05 18:52:24) --- on the heady topic of "Re: Aluminum tubing?" DP> From: Dave Piggin DP> Xref: core-easynews rec.radio.amateur.antenna:218532 > Also, why do we say tube rather than valve? DP> Because a tube allows a substance through it without restriction, a DP> valve is a device for controlling such. DP> Dave Croutons de boeuf! They are all cathode ray tubes. Valve is from the stupide French who couldn't translate tube properly and the Brits then blindly adopted it. A*s*i*m*o*v ... Goose Pester Blondo Yip Lives! Article: 218421 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: V/I ratio is forced to Z0 Message-ID: References: <8b_2f.15566$6e1.12775@newssvr14.news.prodigy.com> <6etok1pcelntp3bkj0hrqi0c3an2an2unv@4ax.com> Date: Wed, 12 Oct 2005 04:50:51 GMT On Wed, 12 Oct 2005 04:06:07 GMT, Cecil Moore wrote: >Owen Duffy wrote: >> The Bird does not measure or report the conditions on the coax, it >> measures and reports the conditions in the immediate region of the >> sampling element which is some 40mm inside the Thruline coupler >> section. > >I don't know what this argument is all about. Consider the >following: > >XMTR---75 ohm coax---Bird---75 ohm load > >Are you saying the Bird's placement will result in a reflection >coefficient of 0.2? I seriously doubt that is true. I don't have the equipment at hand to do that experiment, but I have done another experiment. XMTR -- 2m of RG58 -- Bird43 -- 1.2m of RG213 Bird43 -- 20m RG6 (75 ohms) -- antenna. 1.2m of 50 ohm coax between the Birds is 4.2% of an electrical (wavelength.) I have made measurements with only one 100W slug which is moved from instrument to instrument. The tx was adjusted to 100W forward on the first instrument. Both instruments read 100W forward. Both instruments read 2W reflected. When I swap the instruments around, I get the same results. It is only a simple test, but I am not convinced that measurements from one position are signficantly different to the other position, despite the transmission line "environment" being different. I am not surprised that both instruments read similarly, despite the fact that one doesn't have any 50 ohm coax on the load side of itself, whereas the other one does. Owen -- Article: 218422 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: <8b_2f.15566$6e1.12775@newssvr14.news.prodigy.com> <6etok1pcelntp3bkj0hrqi0c3an2an2unv@4ax.com> Message-ID: Date: Wed, 12 Oct 2005 05:36:38 GMT Owen Duffy wrote: > XMTR -- 2m of RG58 -- Bird43 -- 1.2m of RG213 Bird43 -- 20m RG6 (75 ohms) -- antenna. I don't have any argument with your results. Try this instead. XMTR -- 2m of RG58 -- Bird43 -- 1.2m of RG6 Bird 43 -- 20m RG6 -- antenna The second Bird will NOT indicate the actual SWR on the RG6. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218423 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: V/I ratio is forced to Z0 Message-ID: <3h8pk1hvp80tv1mk0pe86b5jrjjlje15ak@4ax.com> References: <8b_2f.15566$6e1.12775@newssvr14.news.prodigy.com> <6etok1pcelntp3bkj0hrqi0c3an2an2unv@4ax.com> Date: Wed, 12 Oct 2005 06:05:19 GMT On Wed, 12 Oct 2005 05:36:38 GMT, Cecil Moore wrote: >Owen Duffy wrote: >> XMTR -- 2m of RG58 -- Bird43 -- 1.2m of RG213 Bird43 -- 20m RG6 (75 ohms) -- antenna. > >I don't have any argument with your results. Try this instead. > >XMTR -- 2m of RG58 -- Bird43 -- 1.2m of RG6 Bird 43 -- 20m RG6 -- antenna > I won't waste the time, I can predict that they will most likely be different. Transmission line theory tells me that the Z in the region of each Bird will be different, and that will probably result in a different indicated VSWR. It is a sidetrack, just noise. The measurements I reported were identical, although one Bird was surrounded by 50 ohm line, and the other had 75 ohm line on one side of it. The 75 ohm line did not cause a measureable difference in meter readings in that simple trial. Owen -- Article: 218424 of rec.radio.amateur.antenna From: Carl Domanico Subject: For Sale Message-ID: Date: Wed, 12 Oct 2005 07:27:21 GMT Hi I have for sale two Comet/NCG Meters : 1) NCG-3000 118 mHz-530 MHz SWR / Wattmeter 5-20-200 Watts Bought New in Box for $ 110.00...Item is in mint condition. Make offer 1) Comet CMX-3 140 mHz - 525 MHz SWR / Wattmeter 20-50-200 watt Is remotable...Paid $ 170.00 New In Box Item is in Mint condition. Make offer... Thanks Carl N2MFW Article: 218425 of rec.radio.amateur.antenna From: Mike M. Subject: Re: Anyone Have Plans for Dual Band Beam 2m/70cm? Message-ID: References: <1sE2f.349$q%.118@newssvr12.news.prodigy.com> Date: Wed, 12 Oct 2005 07:56:22 GMT On Tue, 11 Oct 2005 01:21:01 GMT, Cecil Moore wrotF: >Hal Rosser wrote: >> The elements for the 70 cm band are so small, they don'r interefere with the >> 2m band > >But the opposite may not be true since 444/3=148. L.B. Cebik has an article on a dual band quad. He uses element placement to reduce interaction between the 2m and 70 cm elements. < http://www.cebik.com/vhf/satq.html> Article: 218426 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: <8b_2f.15566$6e1.12775@newssvr14.news.prodigy.com> <6etok1pcelntp3bkj0hrqi0c3an2an2unv@4ax.com> <3h8pk1hvp80tv1mk0pe86b5jrjjlje15ak@4ax.com> Message-ID: <0S63f.534$dO2.380@newssvr29.news.prodigy.net> Date: Wed, 12 Oct 2005 11:56:44 GMT Owen Duffy wrote: > It is a sidetrack, just noise. The main point of the discussion has been: An SWR meter calibrated for Z0=50 ohms will not accurately report the actual SWR on a line that is not Z0=50 ohms. Of the four following configurations, in a lossless situation, which one accurately reports the SWR on both sides of the SWR meter? 1. XMTR---50 ohm coax---SWR meter---50 ohm coax---load 2. XMTR---50 ohm coax---SWR meter---75 ohm coax---load 3. XMTR---75 ohm coax---SWR meter---50 ohm coax---load 4. XMTR---75 ohm coax---SWR meter---75 ohm coax---load -- 73, Cecil http://www.qsl.net/w5dxp Article: 218427 of rec.radio.amateur.antenna From: "Frank" References: <7etfk1lpvpspfgi7u6vd8u0bm4kc463i44@4ax.com> <0jw2f.9312$y_1.3496@edtnps89> <8g8lk15u9hecqslo7n3udnr6jjpkbjnl7p@4ax.com> <7gU2f.9979$y_1.4296@edtnps89> Subject: Re: How to model on EZNEC Message-ID: Date: Wed, 12 Oct 2005 13:32:16 GMT > With the exception of the sleeve wires, the model follows this > convention and a trial with different end-to-end connections for the > sleeve gives identical results. > > If someone doubts that the sleeve is effective or the model of same is > invalid, as I said before, remove it and place a parallel resonant > trap at the top of the "coax" running from ground to the bottom of the > antenna. The results will be very (but not exactly) similar. > > With a one amp source, there will be a current standing wave on the > "coax" with a peak amplitude of approximately 1/2 amp. Changing the > height above ground changes this dramatically and the angle of maximum > radiation above ground changes dramatically as well. > > Those wanting to spend more time with it can try adding wires to each > end of the sleeve, tying the wires together; changing the length of > the sleeve and re-resonating the rod, and so forth. > > Because the top of the sleeve is a multiwire junction I prefer to use > a separate wire to hold the source. Checking your lines of code more carefully, I see that they are all in the same direction, except for the small radials connecting the top of the sleeves. What I noticed is that the card sequence is not in order, which was why I was confused. Not sure how important this is. What I have noticed is that similar structures (GP with depressed radials, for example) produce erroneous TRP results. It will be interesting to try such computations on variants of your sleeve antenna. My results did not show significant current on the outer shield of the coax. This may be due to my inability to implement the "Mininec" ground. > Since I'm a long time client of Roy's and a beta tester for MultiNEC, > I use EZNEC with MultiNEC as a shell. I get the best of both worlds > and MultiNEC will also invoke Arie's fine program, which I use for the > neat full-color 3-D plotting. EZNEC keeps me honest with all of the > segment length checking, antenna viewing and other fine features. > > MultiNEC offers full spreadsheet entry, and other features too > numerous to mention. It writes EZNEC input files just dandy. It will > do the same with your Nec-Win. Nec-Win Pro does have a Pseudo built-in NEC-Win Plus interface, which allows spread sheet entry, and it will also interface with Excel. I am not familiar with MultiNEC, or EZNEC, although I do have ARRL's EZNEC version, but have never used it. I understand that EZNEC is an excellent program, thought it does not support NEC code entry, or the S/M ground. 73, Frank Article: 218428 of rec.radio.amateur.antenna From: "Frank" References: Subject: Re: EZNEC model of sleeve antenna Message-ID: <%i83f.15845$S4.14328@edtnps84> Date: Wed, 12 Oct 2005 13:35:55 GMT "David" wrote in message news:HIX2f.15350$U51.14571@news-server.bigpond.net.au... > Thank you to whoever provided the coordinates for the model of this > antenna. > > I wrote them down and entered them when I saw them in your posting but the > original email has been automatically removed from the folder in my email > client. > > There has been a lot of discussion and side issues raised from my original > post but I am grateful for you taking the time to provide the information > for me. > > I am a novice with regard to antenna theory and have no previous > experience with antenna modeling. Your post has given me a good starting > point. > I entered the coordinates and (beside initially selecting wavelengths > instead of inches) the model ran fine. > I was then able to scale it up to the frequency of interest (920 MHz) and > now I am playing with the sleeve diameter, sleeve length and radiator > length to observe how these are effecting radiation pattern and SWR. > > There was also mention of a book regarding basic antenna modeling, my next > step will be to purchase a good book to help me understand the process and > limitations etc. > > Thanks again > > Regards > > David Huisman I recommend Cebik's book from www.nittany-scientific.com. The ARRL modeling course is probably similar, since Cebik was also involved in its development. Regards, Frank Article: 218429 of rec.radio.amateur.antenna From: Gene Fuller Subject: Re: Aluminum tubing? References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> Message-ID: Date: Wed, 12 Oct 2005 13:39:25 GMT Roger Conroy wrote: [snip] >>>>>>Why do you guys in the US always omit the "i" in aluminium ? >> >> >>You mean the second "i"? Probably because we spell it correctly: Aluminum. >>;~) > > > But you do it ONLY to Alumin(i)um. What about Lithium, Barium, Chromium, > Ruthenium, Titanium, Uranium, and so on......? Hmmmm, does "so on" also include Lanthanum, Molybdenum, Platinum, and Tantalum? 73, Gene W4SZ Article: 218430 of rec.radio.amateur.antenna Message-ID: <434D1703.8FC61A36@chaio_guido.net> From: Guido Sarducci from NYC Subject: Re: Aluminum tubing? References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> Date: Wed, 12 Oct 2005 14:00:36 GMT Chaio ! I always use the terlit when I am at home because at the malls they are not clean. I also change the earl in my pickup truck. Article: 218431 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Anyone Have Plans for Dual Band Beam 2m/70cm? Date: Wed, 12 Oct 2005 09:44:23 -0500 Message-ID: <1233-434D2147-25@storefull-3256.bay.webtv.net> References: Mike M wrote: "L.B. Cebik has an article on a dual band quad. He uses slement placement to reduce interaction between the 2m and 70cm elements." Sure. Mount the elements for one band at right angles to those for the second band. Best regards, Richard Harrison, KB5WZI Article: 218432 of rec.radio.amateur.antenna From: "Frank" References: <%i83f.15845$S4.14328@edtnps84> Subject: Re: EZNEC model of sleeve antenna Message-ID: Date: Wed, 12 Oct 2005 15:59:12 GMT wrote in message news:gqaqk1tgkhos7o7j4lqi6iqejhhct46sfj@4ax.com... > On Wed, 12 Oct 2005 13:35:55 GMT, "Frank" > wrote: > >>I recommend Cebik's book from www.nittany-scientific.com. The ARRL >>modeling >>course is probably similar, since Cebik was also involved in its >>development. >> > > I have both. In my opinion, the ARRL's modeling course book would a > better choice for those starting out in modeling. That isn't meant > that is limited. Anyone who finishes the course should have an > excellent understand of modeling and able to knowledgeably make > complex models using programs such as EZNEC or NecWinPlus+. > > Nittany's book would be a better choice for those who prefer using NEC > card input formats. > > 73, > Danny, K6MHE Good point. I should have mentioned that the book deals almost exclusively with NEC card input formats. 73, Frank Article: 218433 of rec.radio.amateur.antenna From: Jim Kelley Subject: Re: V/I ratio is forced to Z0 Date: Wed, 12 Oct 2005 10:29:53 -0700 Message-ID: References: <8b_2f.15566$6e1.12775@newssvr14.news.prodigy.com> Cecil Moore wrote: > If there is 75 ohm coax on the input of the Bird, the reflected > power reported by the Bird on the coax will be off by an infinite > percent. That's pretty inaccurate. Why wouldn't the meter correctly indicate the reflection resulting from the mismatch between the 50 ohm wattmeter and the 75 ohm transmission line? ac6xg Article: 218434 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: V/I ratio is forced to Z0 Message-ID: <9elqk1p460cfvln542oulbi74eet2j908j@4ax.com> References: <8b_2f.15566$6e1.12775@newssvr14.news.prodigy.com> <6etok1pcelntp3bkj0hrqi0c3an2an2unv@4ax.com> <3h8pk1hvp80tv1mk0pe86b5jrjjlje15ak@4ax.com> <0S63f.534$dO2.380@newssvr29.news.prodigy.net> Date: Wed, 12 Oct 2005 18:34:35 GMT On Wed, 12 Oct 2005 11:56:44 GMT, Cecil Moore wrote: >Owen Duffy wrote: >> It is a sidetrack, just noise. > >The main point of the discussion has been: An SWR meter >calibrated for Z0=50 ohms will not accurately report the >actual SWR on a line that is not Z0=50 ohms. > No Cecil, the thread subject and the quote of your text in the first message of the post was the main point of discussion: >The transmission line length must only be long enough such that >the V/I ratio is forced to the Z0 value. According to some pretty >smart guys I asked, that's about 2% of a wavelength. It seems that the statement you have quoted is not born out in practice, though I note that you "seriously doubt that is true". I have found out what I needed to know, thanks... Owen -- Article: 218435 of rec.radio.amateur.antenna From: "Fred W4JLE" References: <6muij11sgp4h5hj9u39ndqfir0cocpvkf0@4ax.com> <8fblj1ho8ej0ihucalee6comabmo87h1b3@4ax.com> <11jmc9on86rvfcc@corp.supernews.com> <73063$433c14ac$97d56a13$3806@ALLTEL.NET> <5NX_e.1591$Fi3.75@newssvr29.news.prodigy.net> <1128045830.794934.214900@g14g2000cwa.googlegroups.com> <1129120141.286151.251960@g47g2000cwa.googlegroups.com> Subject: Re: Fractal Antennas Date: Wed, 12 Oct 2005 14:54:37 -0400 Message-ID: <5b34$434d5c2e$97d558d8$9687@ALLTEL.NET> Bill, how can you possibly believe (history aside) that the people from fractenna would do such a thing. Especially since their warm wonderful personalities have enticed all knowledgeable amateurs to use nothing but fractal antennas. "Bill" wrote in message news:1129120141.286151.251960@g47g2000cwa.googlegroups.com... > Only post on usenet by "tennapro" from AOL. He jumps in to defend the > fractenna faction and disappears. We've seen this before. > Article: 218436 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: <8b_2f.15566$6e1.12775@newssvr14.news.prodigy.com> Message-ID: Date: Wed, 12 Oct 2005 19:31:57 GMT Jim Kelley wrote: > > Cecil Moore wrote: >> If there is 75 ohm coax on the input of the Bird, the reflected >> power reported by the Bird on the coax will be off by an infinite >> percent. That's pretty inaccurate. > > Why wouldn't the meter correctly indicate the reflection resulting from > the mismatch between the 50 ohm wattmeter and the 75 ohm transmission line? The question implies that the mismatch would cause appreciable reflections. I have not witnessed that happening at HF but perhaps others have. On MFJ meters, for instance, the one inch wire through the ferrite toroid probably wouldn't cause an appreciable mismatch. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218437 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: Transmitter ALC Date: Wed, 12 Oct 2005 13:24:23 -0500 Message-ID: References: <6shgk11bict76alt5j6gr0d0trekiu2gal@4ax.com> "Owen Duffy" wrote in message news:fdfok11juirunt2ouc175efdsrohpm4ooe@4ax.com... > On Tue, 11 Oct 2005 16:32:59 -0500, "Steve Nosko" > wrote: > > [ clippers active...] Owen, Though this is not antenna talk... Thanks for the confirmation of my half experience, half judgment-based-on-knowledge based understanding. > Unfortunately, there is a growing common belief that unless the ALC > meter is high upscale, then the rig isn't being talked up enough (the > dumbing down of ham radio). snip... My thought is that if you want > audio compression, use a speech processor, not the ALC. Interesting misconception. I'll remember this when I find that some clarification is needed on ALC. A good explanation "tool" is to say that the ALC "meter" deflection is an indication of how much over drive you are trying to give due to too much audio. I understand that it is an indication of the gain reduction being applied to keep the PEP at the design max. If it is done correctly, it should provide no compression effect at all. > Mentioning speech processors. A correctly adjusted speech processor is > proably better protection against overdrive than depending on ALC > alone. The peaks are contained (clipped) and the distortion products > filtered off, before getting near the PA which does not have effective > post filtering for clipping distorion. > Owen > -- I'd be careful in saying it this way because it appears to connect the compression concept with the over drive concept and they are independent concepts. The purpose of ALC is to set the proper PEP level (highest, but not "too much") and the purpose of compression is to improve "talk power / intelligibility" by increasing the average envelope power ( AEP ?) while NOT changing the peak (improve peak-to-average-ratio of speech). 73, Steve, K,9.D;C'I Article: 218438 of rec.radio.amateur.antenna From: "John N9JG" Subject: Data sheet for MTSD-V1 Stepper Motor Driver Board Date: Wed, 12 Oct 2005 14:40:58 -0500 Message-ID: I am in the process of designing a remotely tuned capacitor for a loop antenna. I have just received from Digi-Key a Modern Technology MTSD-V1 Unipolar Stepper Motor Driver Board. Unfortunately, the packing box did not contain a data sheet describing how to use the board. Digi-Key's catalog lists the board's capabilities but does not give information on how to connect to the board. A Google on the board did not give me any links to a data sheet for the board. Has anyone ever used this board, and would you be able to copy the data sheet and send it to me? You can contact me at john@xgotwalsx.com (remove the two 'x' letters from the domain name). Article: 218439 of rec.radio.amateur.antenna From: "John N9JG" Subject: Re: Data sheet for MTSD-V1 Stepper Motor Driver Board Date: Wed, 12 Oct 2005 14:50:36 -0500 Message-ID: References: I am happy to report that Digi-Key customer service promptly emailed me a 7-page PDF file of the data sheet. My hat is off to Digi-Key and its excellent customer service. -- John, N9JG "John N9JG" wrote in message news:dijos8$prf$1@mailhub227.itcs.purdue.edu... >I am in the process of designing a remotely tuned capacitor for a loop >antenna. I have just received from Digi-Key a Modern Technology MTSD-V1 >Unipolar Stepper Motor Driver Board. Unfortunately, the packing box did not >contain a data sheet describing how to use the board. Digi-Key's catalog >lists the board's capabilities but does not give information on how to >connect to the board. A Google on the board did not give me any links to a >data sheet for the board. > > Has anyone ever used this board, and would you be able to copy the data > sheet and send it to me? You can contact me at john@xgotwalsx.com (remove > the two 'x' letters from the domain name). > Article: 218440 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: <8b_2f.15566$6e1.12775@newssvr14.news.prodigy.com> <6etok1pcelntp3bkj0hrqi0c3an2an2unv@4ax.com> <3h8pk1hvp80tv1mk0pe86b5jrjjlje15ak@4ax.com> <0S63f.534$dO2.380@newssvr29.news.prodigy.net> <9elqk1p460cfvln542oulbi74eet2j908j@4ax.com> Message-ID: Date: Wed, 12 Oct 2005 19:52:56 GMT Owen Duffy wrote: > No Cecil, the thread subject and the quote of your text in the first > message of the post was the main point of discussion: Yes, the thread subject was the main point. Z0's other than 50 ohms do not force the V/I ratio to 50 ohms (for matched lines) and 2% of a 10 MHz WL of RG-213 is of a *sufficient* length to force the V/I ratio to 50 ohms. >>The transmission line length must only be long enough such that >>the V/I ratio is forced to the Z0 value. According to some pretty >>smart guys I asked, that's about 2% of a wavelength. I've already apologized for my memory being faulty on that one. If what you want are additional apologies, you've got it. I hereby triple dog apologize for my faulty memory. The above statement was incomplete and was therefore wrong. What more do you want me to say about it? It was wrong, so of course, it "is not born out in practice". > It seems that the statement you have quoted is not born out in > practice, though I note that you "seriously doubt that is true". What I seriously doubted being true is that a 50 ohm Bird wattmeter has a 0.2 reflection coefficient when placed in a 75 ohm feedline. I just don't think that 40mm (1.5") is enough length to establish a 50 ohm environment inside the Bird. But I might be wrong on that one. I know my Autek WM-1 doesn't cause appreciable reflections when placed in a 75 ohm feedline. I think, from the beginning, you have confused what Reg said with what I said. I am basically on your side in the argument. ***Additional Context*** The question of a year ago was not what is the minimum length required to force V/I to Z0 (although that can be had from Kevin's posting quoted from s.p.e.) I was arguing with Reg over whether the lengths of coax into and out of *my* SWR meter forces V/I to be 50 ohms. I use two foot lengths of RG-400. (That's ~2% of a wavelength at 10 MHz.) Two feet is a *sufficient* length to cause V/I to equal Z0 (in a matched line). Two feet is not the *absolute minimum* length but is instead a *sufficient* length and the length I use in my shack. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218441 of rec.radio.amateur.antenna From: Jim Kelley Subject: Re: V/I ratio is forced to Z0 Date: Wed, 12 Oct 2005 12:46:50 -0700 Message-ID: References: <8b_2f.15566$6e1.12775@newssvr14.news.prodigy.com> Cecil Moore wrote: > Jim Kelley wrote: > >> >> Cecil Moore wrote: >> >>> If there is 75 ohm coax on the input of the Bird, the reflected >>> power reported by the Bird on the coax will be off by an infinite >>> percent. That's pretty inaccurate. >> >> >> Why wouldn't the meter correctly indicate the reflection resulting >> from the mismatch between the 50 ohm wattmeter and the 75 ohm >> transmission line? > > > The question implies that the mismatch would cause appreciable > reflections. I have not witnessed that happening at HF but > perhaps others have. On MFJ meters, for instance, the one inch > wire through the ferrite toroid probably wouldn't cause an > appreciable mismatch. The Bird manual shows a section of 50 ohm transmission line. But even the N connectors are 50 ohms. I assume even one of those would show up on a TDR. ac6xg Article: 218442 of rec.radio.amateur.antenna From: "Phil" References: <1233-434D2147-25@storefull-3256.bay.webtv.net> Subject: Re: Anyone Have Plans for Dual Band Beam 2m/70cm? Message-ID: Date: Wed, 12 Oct 2005 20:21:38 GMT Try this link for ideas. http://www.cushcraft.com/support/pdf/a27010s.pdf Phil, KB2HQ "Richard Harrison" wrote in message news:1233-434D2147-25@storefull-3256.bay.webtv.net... > Mike M wrote: > "L.B. Cebik has an article on a dual band quad. He uses slement > placement to reduce interaction between the 2m and 70cm elements." > > Sure. Mount the elements for one band at right angles to those for the > second band. > > Best regards, Richard Harrison, KB5WZI > Article: 218443 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: <8b_2f.15566$6e1.12775@newssvr14.news.prodigy.com> Message-ID: Date: Wed, 12 Oct 2005 20:25:56 GMT Jim Kelley wrote: > The Bird manual shows a section of 50 ohm transmission line. But even > the N connectors are 50 ohms. I assume even one of those would show up > on a TDR. Probably would, but would it cause appreciable reflections? I don't think it would have |rho|=(75-50)/(75+50)=0.2 when used with 75 ohm coax. Owen said something about 40mm. I just don't think 40mm (1.5") is long enough to establish a 50 ohm environment but I could be wrong. I've never owned a Bird. I suspect |rho| would calculate out to be much less than 0.2. And of course there would be two discontinuities, one from 75 ohms to 50 ohms and one from 50 ohms back to 75 ohms. Given the short length between those two discontinuities, one probably interferes with and tends to cancel the effects of the other as would happen with a zero length of feedline. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218444 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FM antenna ambient temperature References: <1129148048.982537.139070@o13g2000cwo.googlegroups.com> Message-ID: <2oe3f.763$q%.605@newssvr12.news.prodigy.com> Date: Wed, 12 Oct 2005 20:30:54 GMT CD wrote: > If you have an FM transmitter setup to transmit 150W and you put a > thermometer about 15ft away with the FM antenna directly pointed at it, > will the thermometer reading change? If the thermometer has a 1/2WL column of mercury, it certainly will. :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 218445 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: Need RDF Yagi alternative Date: Wed, 12 Oct 2005 15:12:56 -0500 Message-ID: References: <1128970687.485157.40010@g44g2000cwa.googlegroups.com> Duncan, This is commonly called the TDOA to distinguish it from the 4-6 antenna Doppler systems. 73, K9DCI, Steve "Duncan" wrote in message news:1128970687.485157.40010@g44g2000cwa.googlegroups.com... > > Jim wrote: > > This isn't strictly a Ham question, but I hope you all can help me anyway. > > > > I am using small transmitters in the 166-167 mhz range in some Box Turtle > > research I am doing. My RDF antenna is a 3 element Yagi designed via > > Yagicad 4.1 which works pretty well. It has 48db front/back and about 90 > > degrees beamwidth in the H pattern. > > > > This works well for initial locating......usually starting 1500 to 2000 feet > > from my transmitter, but the closer I get, the more inaccurate it becomes. > > > > What kind of antenna design could I switch to when I get to close range that > > would have a narrower beam so I could pinpint my target? It would be nice > > to have something smaller than my 35" x 21" yagi for close in work, but the > > beam width is the primary concern. > > > > Yagicad doesn't let me design solely on beam width (at least I haven't > > figured out how) so is there another way to go on this?? > > > > Thanks > > Jim > > > The doppler shift method mentioned by Dave has worked very well for me > but it only gives you a chioce between 2 directions. If you know the > kind of area your turtles are likely to be then it should work > otherwise you can use iyt in conjunction with you yagi antenna to get a > accurate direction. The doppler shift method (unlike directional > antennas) is not affected by signal strength. This is because it works > by using two small antennas and determining which one the radio wave > hits first (this type of device usually generates a tone which > dissapears when the wave hits both antennas at the same time). This > tells you with a good degree of accuracy that the transmitter is in > front of or behind you. > Article: 218446 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: Need RDF Yagi alternative Date: Wed, 12 Oct 2005 15:09:44 -0500 Message-ID: References: Some good suggestions. One caution with "nulling" antennas. You say "small transmitters", so I don't know how much of a factor the following is. Also, if you are using the typical wildlife chirping transmitters, my #2 may not be completely appropriate: When close to the transmitter, RF can enter the receiver directly, via the coax or just the receiver itself. When in the antenna null, this "Blow-by" can exceed the level coming via the antenna and make the null antenna useless. Loops are pretty simple, and the cardiod loop is pretty much an optimum loop. There are two relatively simple solutions. Any of the phase sensing methods can solve this problem. (the Doppler is another solution, but it's not simple). You can also take two or more "nulling" readings at a comfortable distance (terrain permitting) to triangulate the position. I even have a loop for 2M and one for 440 (cute little 1" diameter). One is an offset attenuator. Google on that & you'll see a simple but very effective device except it won't narrow up your beam pattern. A better, though a little more complex is what is commonly called the "TDOA". This is a two antenna phase sensing system which, when well made, gives an indication which allows you to walk right up to the transmitting antennas until the target is actually be in between the two antennas. These can find the keyed 5W. hand held in a shoulder-to-shoulder line-up of people all holding one. The one I designed has an extra FET (not a bunch of ICs) and a center reading meter which gives a left-right indication, nice but not necessary. I don't remember if I have an electronic package on it though. No "u's" in my address. Good luck, & 73, Steve, K9DCI "Jim" wrote in message news:e2bd0$434aabe2$d80c3c80$26657@NAXS.COM... > This isn't strictly a Ham question, but I hope you all can help me anyway. > > I am using small transmitters in the 166-167 mhz range in some Box Turtle > research I am doing. My RDF antenna is a 3 element Yagi designed via > Yagicad 4.1 which works pretty well. It has 48db front/back and about 90 > degrees beamwidth in the H pattern. > > This works well for initial locating......usually starting 1500 to 2000 feet > from my transmitter, but the closer I get, the more inaccurate it becomes. > > What kind of antenna design could I switch to when I get to close range that > would have a narrower beam so I could pinpint my target? It would be nice > to have something smaller than my 35" x 21" yagi for close in work, but the > beam width is the primary concern. > > Yagicad doesn't let me design solely on beam width (at least I haven't > figured out how) so is there another way to go on this?? > > Thanks > Jim > > Article: 218447 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: Need RDF Yagi alternative Date: Wed, 12 Oct 2005 15:11:29 -0500 Message-ID: References: wrote in message news:judlk1psq9vm45ektnsjfis9ovu1fgav0r@4ax.com... > On Tue, 11 Oct 2005 01:03:34 -0400, "Jim" wrote: > > ...> > You already got two good suggestions from others. Here's a third. > Build a MOXON square, less gain than yagi but if built right the MOXON > has a very distinct readward null, you exploit the null. Another > small advantage is it's smaller than a 2 element yagi for the same > band. > > Allison Look up the "Tape Measure Yagi" It is designed to have a null off the back, but you'll have to adjust the center freq. 73, Steve, K,9.D.C'I > > > Article: 218448 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: Need RDF Yagi alternative Date: Wed, 12 Oct 2005 15:14:42 -0500 Message-ID: References: <1128970687.485157.40010@g44g2000cwa.googlegroups.com> I forgot about these. These are easier to make than the "cardioid loops". K,9.D;C'I "Dave" wrote in message news:vuidnQp82IrxXtfeRVn-3Q@crocker.com... > actually... for some reason i didn't put it on that web page, but you can > have a unidirectional null with that simple system. to do that you make the > antennas 1/4 wavelength apart and make one feed line 1/4 wave longer than > the other. in this way you get a cardioid pattern since the only direction > that won't have a phase shift is when the signal gets to the antenna with > the longer feedline first and the other one exactly 1/4 cycle later. just > be sure to take the coax velocity factor into account. > > "Duncan" wrote in message > news:1128970687.485157.40010@g44g2000cwa.googlegroups.com... > > > > Jim wrote: > >> This isn't strictly a Ham question, but I hope you all can help me > >> anyway. > >> > >> I am using small transmitters in the 166-167 mhz range in some Box Turtle > >> research I am doing. My RDF antenna is a 3 element Yagi designed via > >> Yagicad 4.1 which works pretty well. It has 48db front/back and about 90 > >> degrees beamwidth in the H pattern. > >> > >> This works well for initial locating......usually starting 1500 to 2000 > >> feet > >> from my transmitter, but the closer I get, the more inaccurate it > >> becomes. > >> > >> What kind of antenna design could I switch to when I get to close range > >> that > >> would have a narrower beam so I could pinpint my target? It would be > >> nice > >> to have something smaller than my 35" x 21" yagi for close in work, but > >> the > >> beam width is the primary concern. > >> > >> Yagicad doesn't let me design solely on beam width (at least I haven't > >> figured out how) so is there another way to go on this?? > >> > >> Thanks > >> Jim > > > > > > The doppler shift method mentioned by Dave has worked very well for me > > but it only gives you a chioce between 2 directions. If you know the > > kind of area your turtles are likely to be then it should work > > otherwise you can use iyt in conjunction with you yagi antenna to get a > > accurate direction. The doppler shift method (unlike directional > > antennas) is not affected by signal strength. This is because it works > > by using two small antennas and determining which one the radio wave > > hits first (this type of device usually generates a tone which > > dissapears when the wave hits both antennas at the same time). This > > tells you with a good degree of accuracy that the transmitter is in > > front of or behind you. > > > > Article: 218449 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: Need RDF Yagi alternative Date: Wed, 12 Oct 2005 15:26:17 -0500 Message-ID: References: <20rq13-5m2.ln1@p400bob.personal.cox.net> <650c$434afc93$d80c392d$667@NAXS.COM> "Jim" wrote in message news:650c$434afc93$d80c392d$667@NAXS.COM... > True, I haven't thought of everything, but I have done this: > > ... My > transmitter antennas are horizontal trailing insulated wire. I think talk about polarization is relatively meaningless with this. I have a > fairly long cable so am able to hold it at arm's length from my body. It > does have a very good null and I use both front and null in my RDFing. With a good rear nul, your presence in the rear should give minimal effect. > > My radio might not be the best as far as sheilding.....it is plastic cased. > So I made a fiderglass holster for it with aluminum screen embedded in the > fiberglass resin all the way around...kind of like a Faraday cage. I don't > really know how this helps. It is not grounded, Ground is sort of meaningless at this point. Look up the "Offset Attenuator". 73, Steve, K,9.D;C'I Article: 218450 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: Need RDF Yagi alternative Date: Wed, 12 Oct 2005 15:37:17 -0500 Message-ID: References: > Sorry I'm too tired to look up a better example, but > http://members.aol.com/BmgEngInc/Adcock.html > is still pretty good. It's essentially about like the > "phased verticals" the other fellow mentioned, in that > they both result in a "cardioid" pattern, i.e. a sharp > *notch* in the pattern, broadside to the array in this > case. Thanks, Sluggo, but this is partly an oops! The BMG pages are a very good resource (as are many RDF sites). OOPS! The Adcock is just like a loop -- two nulls off both broadside faces. The version that looks similar (previously mentioned) where you have two vertical dipoles spaced 1/4 wave and a 3/4 wave connecting cross-feed line gives the cardioid -- one null. "Sluggo" wrote in message news:h3dmk1p0od57ig3q5qpm1qgq5gkdtdq3lm 73, Steve, K,9.D;C'I Article: 218451 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: Need RDF Yagi alternative Date: Wed, 12 Oct 2005 15:20:22 -0500 Message-ID: References: <20rq13-5m2.ln1@p400bob.personal.cox.net> "Bruce" wrote in message news:Xns96EBC33DC1298xxxyyyzzz@216.77.188.18... > ... > > Now, if the receiver IS well shielded enough, if you can insert a > switchable attenuator in the coax, you can reduce the signal strength > significantly...and, FM receivers get very non-linear below about 20dB > quieting, they quiet faster than the actual input. In otherwords, you > could get 3-4 dB quieting change for 1dB of singal change. What this will > do is make you antenna pattern SEEM narrower....> -Bruce Two things here. The "offset attenuator" gets you the equivalent to a shielded receiver without the shielding and very simple construction. There are designs on the web for "quieting meters" and I have even seen one design where the receiver s-meter signal was summed with the quieting signal resulting in one very large dynamic range signal strength indicator. 73, Steve, K,9.D;C'I Article: 218452 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: Need RDF Yagi alternative Date: Wed, 12 Oct 2005 15:29:02 -0500 Message-ID: References: <20rq13-5m2.ln1@p400bob.personal.cox.net> <650c$434afc93$d80c392d$667@NAXS.COM> "Bob Bob" wrote in message news:u90u13-go9.ln1@p400bob.personal.cox.net... > Hi again Jim > > I'd suspect you need an attenuator of maybe 60dB in 6dB steps! I cant > see the 10dB variable one as being useful. Of course at 50dB or more > coax leakage might be an issue! When you see the numbers for the Offset attenuator you won't believe them, though true. > Okay on the screening. Well as I mentioned the test is to plug a 50 ohm > load in the antenna socket and see if it responds at a distance of say > 5ft. If it doesnt then dont worry about screening. If it does it depends > on how much and then whether things like coax leakage have to be > factored in. Good test. 73, Steve, K,9.D;C'I Article: 218453 of rec.radio.amateur.antenna From: Jim Kelley Subject: Re: V/I ratio is forced to Z0 Date: Wed, 12 Oct 2005 14:11:41 -0700 Message-ID: References: <8b_2f.15566$6e1.12775@newssvr14.news.prodigy.com> Cecil Moore wrote: > Jim Kelley wrote: > >> The Bird manual shows a section of 50 ohm transmission line. But even >> the N connectors are 50 ohms. I assume even one of those would show >> up on a TDR. > > > Probably would, but would it cause appreciable reflections? > I don't think it would have |rho|=(75-50)/(75+50)=0.2 > when used with 75 ohm coax. Owen said something about 40mm. > I just don't think 40mm (1.5") is long enough to establish > a 50 ohm environment but I could be wrong. I've never owned > a Bird. I suspect |rho| would calculate out to be much less > than 0.2. And of course there would be two discontinuities, > one from 75 ohms to 50 ohms and one from 50 ohms back to 75 > ohms. Given the short length between those two discontinuities, > one probably interferes with and tends to cancel the effects > of the other as would happen with a zero length of feedline. Ummm, I don't know, Cecil......sounds a little fishy to me. ac6xg Article: 218454 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: How to model on EZNEC References: <7etfk1lpvpspfgi7u6vd8u0bm4kc463i44@4ax.com> <0jw2f.9312$y_1.3496@edtnps89> <8g8lk15u9hecqslo7n3udnr6jjpkbjnl7p@4ax.com> <7gU2f.9979$y_1.4296@edtnps89> <6itqk1h878ujh8v7h0e3tfslj6apsfk779@4ax.com> Message-ID: Date: Wed, 12 Oct 2005 21:22:36 GMT Wes Stewart wrote: > I don't know what "S/M" ground is, ... Sado/Masochistic? :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 218455 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: <8b_2f.15566$6e1.12775@newssvr14.news.prodigy.com> Message-ID: <7gf3f.644$dO2.96@newssvr29.news.prodigy.net> Date: Wed, 12 Oct 2005 21:30:43 GMT Jim Kelley wrote: > Ummm, I don't know, Cecil......sounds a little fishy to me. Let's say you had a one inch piece of 50 ohm coax in the middle of a longer piece of 75 ohm coax. I'll bet the reflections from one discontinuity would virtually cancel the reflections from the other discontinuity. After all, the math should work if the length of the 50 ohm piece is zero, or 1/2WL, or 1WL, or ... In fact, a one inch piece of 50 ohm coax should cause the same steady-state interference conditions as a (one inch plus one wavelength) piece of 50 ohm coax. Don't you agree? -- 73, Cecil http://www.qsl.net/w5dxp Article: 218456 of rec.radio.amateur.antenna From: Jim Kelley Subject: Re: V/I ratio is forced to Z0 Date: Wed, 12 Oct 2005 14:38:22 -0700 Message-ID: References: <8b_2f.15566$6e1.12775@newssvr14.news.prodigy.com> <7gf3f.644$dO2.96@newssvr29.news.prodigy.net> Cecil Moore wrote: > Jim Kelley wrote: > >> Ummm, I don't know, Cecil......sounds a little fishy to me. > > > Let's say you had a one inch piece of 50 ohm coax in the > middle of a longer piece of 75 ohm coax. I'll bet the > reflections from one discontinuity would virtually > cancel the reflections from the other discontinuity. > After all, the math should work if the length of the > 50 ohm piece is zero, or 1/2WL, or 1WL, or ... > > In fact, a one inch piece of 50 ohm coax should cause > the same steady-state interference conditions as a (one > inch plus one wavelength) piece of 50 ohm coax. Don't > you agree? So basically you want me to agree that it's ok to use 75 ohm connectors in a 50 ohm system - as long as you use two of them separated by 0, 1/2, or 1 (etc) wavelength. Could be true, I suppose. Still, I'd rather you tried it out on your radio first. :-) ac6xg Article: 218457 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: <8b_2f.15566$6e1.12775@newssvr14.news.prodigy.com> <7gf3f.644$dO2.96@newssvr29.news.prodigy.net> Message-ID: Date: Wed, 12 Oct 2005 21:52:45 GMT Jim Kelley wrote: > So basically you want me to agree that it's ok to use 75 ohm connectors > in a 50 ohm system ... Heck, you probably already use PL-239's. :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 218458 of rec.radio.amateur.antenna From: Owen Duffy Subject: Mythbusters: V/I ratio is forced to Z0 Message-ID: <440rk1pg559akgta2q4d38s4le3noihnp8@4ax.com> Date: Wed, 12 Oct 2005 22:09:51 GMT The myth: Measurements with a Bird 43 of the conditions on the Thruline section are invalid unless it has some minimum length of 50 ohm line on both sides of itself. I have performed a test using components at hand where the Bird 43 has 75 ohm line on both sides of itself, and the test configuration is designed to present a 50+j0 ohm load at the point where the Bird 43 sampling element is located. The question is, how does the Bird respond? The test in detail. Each component is in a list from the source to the load: IC706IIG 1m RG58 with UHF connectors MFJ949E ATU 3m RG6 (Zo=75 ohm) with BNC connectors Bird 43 5.27m Belden 9275 (Zo=75 ohm, vf=0.83) with BNC connectors 50 ohm dummy load Short adapters were used to connect to the Bird's Type N connectors, the dummy load's Type N connectors and the MFJ949 UHF connector. The half wave resonance of the 5.27m length of RG6 was determined by s/c one end and connecting the other end via an adapter to a MFJ259B and finding the impedance dip at 23.05MHz. The calculated vf from this test is 0.81, which reconciles reasonably with the specs. Free space wavelenght at the test frequency is 13m. The transmitter was set to 23.05MHz, and the ATU tuned to develop rated power output. The ATU is only used to present the rated load to the transmitter so as to obtain 100W for the test, to suit the Bird 43 element. It is inconsequential to the DUT (the Bird 43). With this configuration, it is expected that the impedance at the Bird 43 is approximately 50+j0, and that there would be almost zero reflected power. The Bird 43 indicated 100W forward power and a quarter of a needle width detection on reflected power. The Bird 43 would appear to provide valid readings for the conditions on the Bird 43 Thruline section in this case, notwithstanding that there is not any 50 ohm transmission line attached to the Bird 43 + N-BNC adapters. The myth that measurements with a Bird 43 of the conditions on the Thruline section are invalid unless it has some minimum length of 50 ohm line on both sides of itself is BUSTED. Has anyone experimental evidence to the contrary? Owen PS: I hasten to add / apologise, I do not watch much television, but I was forced to endure Mythbusters when visiting a friend recently. It's about as scientific as what goes on here, so I thought the style appropriate! -- Article: 218459 of rec.radio.amateur.antenna From: "Fred W4JLE" References: <1129148048.982537.139070@o13g2000cwo.googlegroups.com> <2oe3f.763$q%.605@newssvr12.news.prodigy.com> Subject: Re: FM antenna ambient temperature Date: Wed, 12 Oct 2005 18:20:26 -0400 Message-ID: But once it heats, it will no longer be a half wave. What then? "Cecil Moore" wrote in message news:2oe3f.763$q%.605@newssvr12.news.prodigy.com... > CD wrote: > > If you have an FM transmitter setup to transmit 150W and you put a > > thermometer about 15ft away with the FM antenna directly pointed at it, > > will the thermometer reading change? > > If the thermometer has a 1/2WL column of mercury, > it certainly will. :-) > -- > 73, Cecil http://www.qsl.net/w5dxp Article: 218460 of rec.radio.amateur.antenna From: Allodoxaphobia Subject: Re: FM antenna ambient temperature Date: 12 Oct 2005 22:45:10 GMT Message-ID: References: <1129148048.982537.139070@o13g2000cwo.googlegroups.com> <2oe3f.763$q%.605@newssvr12.news.prodigy.com> On Wed, 12 Oct 2005 18:20:26 -0400, Fred W4JLE wrote: > "Cecil Moore" wrote: >> CD wrote: >> > If you have an FM transmitter setup to transmit 150W and you put a >> > thermometer about 15ft away with the FM antenna directly pointed at it, >> > will the thermometer reading change? >> >> If the thermometer has a 1/2WL column of mercury, >> it certainly will. :-) > > But once it heats, it will no longer be a half wave. What then? Thermal Modulation. Article: 218461 of rec.radio.amateur.antenna From: Jim Kelley Subject: Re: V/I ratio is forced to Z0 Date: Wed, 12 Oct 2005 15:38:11 -0700 Message-ID: References: <8b_2f.15566$6e1.12775@newssvr14.news.prodigy.com> <7gf3f.644$dO2.96@newssvr29.news.prodigy.net> Cecil Moore wrote: > Jim Kelley wrote: > >> So basically you want me to agree that it's ok to use 75 ohm >> connectors in a 50 ohm system ... > > > Heck, you probably already use PL-239's. :-) When I use them, they're effectively 50 ohm connectors. What are they when you use them, Cecil? :-) ac6xg Article: 218462 of rec.radio.amateur.antenna From: Jim Kelley Subject: Re: Mythbusters: V/I ratio is forced to Z0 Date: Wed, 12 Oct 2005 16:13:24 -0700 Message-ID: References: <440rk1pg559akgta2q4d38s4le3noihnp8@4ax.com> Owen Duffy wrote: > The myth: Measurements with a Bird 43 of the conditions on the > Thruline section are invalid unless it has some minimum length of 50 > ohm line on both sides of itself. > > I have performed a test using components at hand where the Bird 43 has > 75 ohm line on both sides of itself, and the test configuration is > designed to present a 50+j0 ohm load at the point where the Bird 43 > sampling element is located. The question is, how does the Bird > respond? > > The test in detail. Each component is in a list from the source to the > load: > > IC706IIG > 1m RG58 with UHF connectors > MFJ949E ATU > 3m RG6 (Zo=75 ohm) with BNC connectors > Bird 43 > 5.27m Belden 9275 (Zo=75 ohm, vf=0.83) with BNC connectors > 50 ohm dummy load > > Short adapters were used to connect to the Bird's Type N connectors, > the dummy load's Type N connectors and the MFJ949 UHF connector. > > The half wave resonance of the 5.27m length of RG6 was determined by > s/c one end and connecting the other end via an adapter to a MFJ259B > and finding the impedance dip at 23.05MHz. The calculated vf from this > test is 0.81, which reconciles reasonably with the specs. Free space > wavelenght at the test frequency is 13m. > > The transmitter was set to 23.05MHz, and the ATU tuned to develop > rated power output. The ATU is only used to present the rated load to > the transmitter so as to obtain 100W for the test, to suit the Bird 43 > element. It is inconsequential to the DUT (the Bird 43). > > With this configuration, it is expected that the impedance at the Bird > 43 is approximately 50+j0, and that there would be almost zero > reflected power. > > The Bird 43 indicated 100W forward power and a quarter of a needle > width detection on reflected power. > > The Bird 43 would appear to provide valid readings for the conditions > on the Bird 43 Thruline section in this case, notwithstanding that > there is not any 50 ohm transmission line attached to the Bird 43 + > N-BNC adapters. > > The myth that measurements with a Bird 43 of the conditions on the > Thruline section are invalid unless it has some minimum length of 50 > ohm line on both sides of itself is BUSTED. > > Has anyone experimental evidence to the contrary? > > Owen What made you decide to use 23.05 MHz and 5.27 meters of .81 VF feedline? ac6xg Article: 218463 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: V/I ratio is forced to Z0 References: <8b_2f.15566$6e1.12775@newssvr14.news.prodigy.com> <7gf3f.644$dO2.96@newssvr29.news.prodigy.net> Message-ID: Date: Wed, 12 Oct 2005 23:50:46 GMT Jim Kelley wrote: > When I use them, they're effectively 50 ohm connectors. What are they > when you use them, Cecil? :-) PL-259's are notorious for not being 50 ohms. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218464 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Mythbusters: V/I ratio is forced to Z0 Message-ID: <007rk194l9s3mnme1cddjuh8naeuu7dpju@4ax.com> References: <440rk1pg559akgta2q4d38s4le3noihnp8@4ax.com> Date: Wed, 12 Oct 2005 23:28:22 GMT On Wed, 12 Oct 2005 16:13:24 -0700, Jim Kelley wrote: > > >Owen Duffy wrote: > >> The myth: Measurements with a Bird 43 of the conditions on the >> Thruline section are invalid unless it has some minimum length of 50 >> ohm line on both sides of itself. >> >> I have performed a test using components at hand where the Bird 43 has >> 75 ohm line on both sides of itself, and the test configuration is >> designed to present a 50+j0 ohm load at the point where the Bird 43 >> sampling element is located. The question is, how does the Bird >> respond? >> >> The test in detail. Each component is in a list from the source to the >> load: >> >> IC706IIG >> 1m RG58 with UHF connectors >> MFJ949E ATU >> 3m RG6 (Zo=75 ohm) with BNC connectors >> Bird 43 >> 5.27m Belden 9275 (Zo=75 ohm, vf=0.83) with BNC connectors >> 50 ohm dummy load >> >> Short adapters were used to connect to the Bird's Type N connectors, >> the dummy load's Type N connectors and the MFJ949 UHF connector. >> >> The half wave resonance of the 5.27m length of RG6 was determined by >> s/c one end and connecting the other end via an adapter to a MFJ259B >> and finding the impedance dip at 23.05MHz. The calculated vf from this >> test is 0.81, which reconciles reasonably with the specs. Free space >> wavelenght at the test frequency is 13m. >> >> The transmitter was set to 23.05MHz, and the ATU tuned to develop >> rated power output. The ATU is only used to present the rated load to >> the transmitter so as to obtain 100W for the test, to suit the Bird 43 >> element. It is inconsequential to the DUT (the Bird 43). >> >> With this configuration, it is expected that the impedance at the Bird >> 43 is approximately 50+j0, and that there would be almost zero >> reflected power. >> >> The Bird 43 indicated 100W forward power and a quarter of a needle >> width detection on reflected power. >> >> The Bird 43 would appear to provide valid readings for the conditions >> on the Bird 43 Thruline section in this case, notwithstanding that >> there is not any 50 ohm transmission line attached to the Bird 43 + >> N-BNC adapters. >> >> The myth that measurements with a Bird 43 of the conditions on the >> Thruline section are invalid unless it has some minimum length of 50 >> ohm line on both sides of itself is BUSTED. >> >> Has anyone experimental evidence to the contrary? >> >> Owen > >What made you decide to use 23.05 MHz and 5.27 meters of .81 VF feedline? > >> I have performed a test using components at hand where the Bird 43 has >ac6xg -- Article: 218465 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Mythbusters: V/I ratio is forced to Z0 References: <440rk1pg559akgta2q4d38s4le3noihnp8@4ax.com> Message-ID: Date: Thu, 13 Oct 2005 01:43:48 GMT Owen Duffy wrote: > The myth: Measurements with a Bird 43 of the conditions on the > Thruline section are invalid unless it has some minimum length of 50 > ohm line on both sides of itself. > > I have performed a test using components at hand where the Bird 43 has > 75 ohm line on both sides of itself, and the test configuration is > designed to present a 50+j0 ohm load at the point where the Bird 43 > sampling element is located. The question is, how does the Bird > respond? > > The test in detail. Each component is in a list from the source to the > load: > > IC706IIG > 1m RG58 with UHF connectors > MFJ949E ATU > 3m RG6 (Zo=75 ohm) with BNC connectors > Bird 43 > 5.27m Belden 9275 (Zo=75 ohm, vf=0.83) with BNC connectors > 50 ohm dummy load > > Short adapters were used to connect to the Bird's Type N connectors, > the dummy load's Type N connectors and the MFJ949 UHF connector. > > The half wave resonance of the 5.27m length of RG6 was determined by > s/c one end and connecting the other end via an adapter to a MFJ259B > and finding the impedance dip at 23.05MHz. The calculated vf from this > test is 0.81, which reconciles reasonably with the specs. Free space > wavelenght at the test frequency is 13m. > > The transmitter was set to 23.05MHz, and the ATU tuned to develop > rated power output. The ATU is only used to present the rated load to > the transmitter so as to obtain 100W for the test, to suit the Bird 43 > element. It is inconsequential to the DUT (the Bird 43). > > With this configuration, it is expected that the impedance at the Bird > 43 is approximately 50+j0, and that there would be almost zero > reflected power. > > The Bird 43 indicated 100W forward power and a quarter of a needle > width detection on reflected power. > > The Bird 43 would appear to provide valid readings for the conditions > on the Bird 43 Thruline section in this case, notwithstanding that > there is not any 50 ohm transmission line attached to the Bird 43 + > N-BNC adapters. > > The myth that measurements with a Bird 43 of the conditions on the > Thruline section are invalid unless it has some minimum length of 50 > ohm line on both sides of itself is BUSTED. Actually, the results of your experiment proves the myth to be true and not to be a myth at all. There's 104.17 watts of forward power through the Bird and 4.17 watts of reflected power back through the Bird. Why does the Bird ignore those actual power values? > Has anyone experimental evidence to the contrary? Yes, your experiment. Assuming 100 watts delivered to the load, the forward power on the 75 ohm coax is actually about 104.17 watts so the Bird's forward power reading is in error by 4.17 watts. The reflected power on the 75 ohm coax is about 4.17 watts so the Bird's reflected power reading is in error by close to an infinite percentage. The Bird 43 is reading neither of the actual power values correctly. All you have just proven is that the Bird 43 gives invalid readings when it is in a 75 ohm environment. THERE ARE ABOUT 4.17 WATTS OF REFLECTED ENERGY FLOWING BACK THROUGH THE BIRD AND THE BIRD COMPLETELY IGNORES IT. So the Bird is not even yielding valid readings for forward and reflected power through itself. That's exactly what I have been saying all along. If it were calibrated for 75 ohms, it would indicate the correct values. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218466 of rec.radio.amateur.antenna From: Sluggo Subject: Re: Need RDF Yagi alternative Message-ID: References: Date: Thu, 13 Oct 2005 02:53:32 GMT On Wed, 12 Oct 2005 15:37:17 -0500, "Steve Nosko" wrote: >OOPS! The Adcock is just like a loop -- two nulls off both broadside faces. >The version that looks similar (previously mentioned) where you have two >vertical dipoles spaced 1/4 wave and a 3/4 wave connecting cross-feed line >gives the cardioid -- one null. > >"Sluggo" wrote in message >news:h3dmk1p0od57ig3q5qpm1qgq5gkdtdq3lm > > > 73, Steve, K,9.D;C'I > Thanks for the correction; I'm only in my 40's but I've been hamming a long time, and the years are starting to blur... Now that I think back on my "real world" experience, the boom on what I thought was an Adcock could well have been a wavelength at 2M, tho, as I said, it's kinda fuzzy now... so it may be that the elements were NOT fed at the center. Oh well, either way, a good notch is going to beat the best yagi. Man, those must be some tasty turtles, to go to all this trouble to track 'em down... 73, tnx agn.. Sluggo Article: 218467 of rec.radio.amateur.antenna From: nospam@nouce.bellatlantic.net Subject: Re: Need RDF Yagi alternative Message-ID: <05jrk1lj5ghbf01f8mqe0m8ijie1oilgbr@4ax.com> References: Date: Thu, 13 Oct 2005 02:56:22 GMT On Wed, 12 Oct 2005 15:11:29 -0500, "Steve Nosko" wrote: > > wrote in message >news:judlk1psq9vm45ektnsjfis9ovu1fgav0r@4ax.com... >> On Tue, 11 Oct 2005 01:03:34 -0400, "Jim" wrote: >> >> ...> >> You already got two good suggestions from others. Here's a third. >> Build a MOXON square, less gain than yagi but if built right the MOXON >> has a very distinct readward null, you exploit the null. Another >> small advantage is it's smaller than a 2 element yagi for the same >> band. >> >> Allison >Look up the "Tape Measure Yagi" It is designed to have a null off the back, >but you'll have to adjust the center freq. >73, Steve, K,9.D.C'I I've built both. The Tape measure yagi is not nearly as good off the back and a bit larger. Moxon well done is an easy 35+ db null off the back and sharper. Allison Article: 218468 of rec.radio.amateur.antenna From: "Asimov" Subject: Re: Aluminum tubing? Message-ID: References: Date: Thu, 13 Oct 2005 04:11:02 GMT "Gene Fuller" bravely wrote to "All" (12 Oct 05 13:39:25) --- on the heady topic of "Re: Aluminum tubing?" GF> From: Gene Fuller GF> Xref: core-easynews rec.radio.amateur.antenna:218617 GF> Roger Conroy wrote: [,,,] > But you do it ONLY to Alumin(i)um. What about Lithium, Barium, Chromium, > Ruthenium, Titanium, Uranium, and so on......? GF> Hmmmm, does "so on" also include Lanthanum, Molybdenum, Platinum, and GF> Tantalum? What about wolfram, (aka tungsten)!? A*s*i*m*o*v ... One tequila, two tequila, three tequila, floor.... Article: 218469 of rec.radio.amateur.antenna From: N7ZZT - Eric Oyen Subject: Re: Fractal Antennas References: <6muij11sgp4h5hj9u39ndqfir0cocpvkf0@4ax.com> <8fblj1ho8ej0ihucalee6comabmo87h1b3@4ax.com> <11jmc9on86rvfcc@corp.supernews.com> <73063$433c14ac$97d56a13$3806@ALLTEL.NET> <5NX_e.1591$Fi3.75@newssvr29.news.prodigy.net> <1128045830.794934.214900@g14g2000cwa.googlegroups.com> <1129120141.286151.251960@g47g2000cwa.googlegroups.com> <5b34$434d5c2e$97d558d8$9687@ALLTEL.NET> Message-ID: Date: Thu, 13 Oct 2005 00:02:33 -0700 Fred W4JLE wrote: > Bill, how can you possibly believe (history aside) that the people from > fractenna would do such a thing. > > Especially since their warm wonderful personalities have enticed all > knowledgeable amateurs to use nothing but fractal antennas. > > "Bill" wrote in message > news:1129120141.286151.251960@g47g2000cwa.googlegroups.com... >> Only post on usenet by "tennapro" from AOL. He jumps in to defend the >> fractenna faction and disappears. We've seen this before. >> not all. Some of the antennas that fractenna, inc. supposedly manufactures were put up for a "test case" to some hams. I had initially requested to be one of those hams. after a small number of e-mail exchanges, I never heard anything further from fractenna, inc or any person there-in. thus, I tend not to take that company, or its current CEO/CTO and resident "engineer" very seriously. in fact, I tale exception to a company that has attempted to sue another company from overseas in an attempt to limit their ability to market a competing product here in the states. so, my question is this: whats the real deal with fractal antennas and why is it that all information that can be found about them so vague in nature? -- DE N7ZZT Eric Oyen Phoenix, Arizona e-mail: n7zzt(at)hotmail(dot)com the difference between intelligence and stupidity is that intelligence has its limits. Article: 218470 of rec.radio.amateur.antenna From: kashe@sonic.net Subject: Re: Aluminum tubing? Message-ID: <263sk1phir2c6th6q22ibtl9v47mva6fhe@4ax.com> References: <1128562179_21@isp.n> <4348f9f7.286775451@news.blueyonder.co.uk> Date: Thu, 13 Oct 2005 07:29:29 GMT On Wed, 12 Oct 2005 13:39:25 GMT, Gene Fuller wrote: >Roger Conroy wrote: > >[snip] > >>>>>>>Why do you guys in the US always omit the "i" in aluminium ? >>> >>> >>>You mean the second "i"? Probably because we spell it correctly: Aluminum. >>>;~) >> >> >> But you do it ONLY to Alumin(i)um. What about Lithium, Barium, Chromium, >> Ruthenium, Titanium, Uranium, and so on......? > >Hmmmm, does "so on" also include Lanthanum, Molybdenum, Platinum, and >Tantalum? > >73, >Gene >W4SZ Not to mention Adnauseam. "-)