Daily GLOWBUGS
Digest: V1 #43
via AB4EL Web Digests @ SunSITE
Purpose: building and operating vacuum tube-based QRP rigs
Subject: glowbugs V1 #43
glowbugs Tuesday, May 27 1997 Volume 01 : Number 043
Date: Sun, 25 May 1997 18:35:04 -0700 (PDT)
From: tomrice@netcom.com (Tom R. Rice)
Subject: Inca Transformer Info?
I've come across a strange transformer, which, if
it is what I suspect, i.e., a plate-to-line dude,
could be very useful for my upcoming AM rig.
It's labelled:
Inca Transformer No. GH 15
Phelps Dodge Copper Products Corporation
Inca Manufacturing Division, Los Angeles, Calif.
An ohmmeter check reveals a balanced winding pair on
one side and a pair of tapped, balanced windings on the
"low" side.
Apologies for the multiple postings; with four radio
lists to deal with, I'm trying to cover all the bases ;-)
If someone can come up with the actual characteristics,
'twould be very nice indeed.
Thanks in advance, WB6BYH
"Remember, you must always grind forward, never backwards."
-- Sally to Buster in "The Cameraman"
- --
"Start off every day with a smile and get it over with." --W.C.Fields
Tom R. Rice
tomrice@netcom.com
CIS: 71160,1122
Date: Mon, 26 May 1997 00:42:55 -0500 (CDT)
From: mjsilva@ix.netcom.com (michael silva)
Subject: Re: ? on regens
Lee wrote:
<report of experiments removed>
>Why then do most all regen schematics call
>for a audio choke load on det. As far as I can see
>they causwe hum without any other advantages
>except when you have a low amount of b+ to work
>with. Am running 125v on plate and it osc at about
>15v on screen.
Thanks for the report, Lee. I think you've got the answer in your
comments above -- I believe it is a throwback to the days of low plate
voltages. The only other advantage I can see to a plate choke is that
it can be turned into a resonant audio load to provide some peaking.
BTW, the rule I've seen is that screen grid tubes make the most
sensitive detectors at around 30 volts on the screen. Just for grins
you might want to try reducing your feedback coupling to oscillate at
30 volts on the screen and see if it makes much difference.
73,
Mike, KK6GM
Date: Mon, 26 May 1997 01:36:28 -0500 (CDT)
From: Chris Broadbent <cfb@bga.com>
Subject: Bad GRC-109 Experience plus RX vs RX/TX Antenna Performance.
I had an unpleasant experience with my newly aquired GRC-109.
Yesterday, I bought a 6 volt lead-acid battery for remote operation. I have
visions of using the 109 when camping. Unfortunately, I could find either
6AH batteries, or ones the size of a normal 12V car battery with 560 CA
rating (they didn't state the AH rating)! At $30 for the big battery, and
$10 for the small one, I chose a big one, given the 13A draw of the 109 on
transmit.
Anyways, when trying out the power supply with my new battery, I found that
the vibrator didn't operate. Upon removing it from the PSU and determining
that 6V was reaching its socket just fine, I tried to power the vibrator
directly, first through high wattage resistors. I kept on dropping the
resistance, with no sign of life. Eventually, having no further choice, I
simply connected straight to the battery. Lo and Behold! It came to life.
I guess the arcing on the contacts may have cleaned them. Drastic, but it
worked!
Delighted, I re-inserted the now working vibrator (ugh, perhaps there is a
better choice of words, but y'all know what I mean). It worked just fine.
One thing of note was the somewhat higher (and correct) TX HT voltage. No
problem, thought I.
In my first post on the condition of my 109, I mentioned possible battery
acid damage to the plug surface and one knob. I guess the acid had made its
way into the TX power plug. Although able to withstand the lower voltage
when run from the mains (due probably to the 130V setting I use), the plug
did not do so well with the higher potential. There was a bright flash, a
loud bang and a spurt of flame from it, impinging on the PSU TX socket. The
15A fuse blew, probably saving the PSU.
Upon examination of the TX plug, I found a crack in it, going from the HT
pin through the inert pin to the ground pin. It also scorched the surface
of the PSU TX socket (a small area of surface damage only, I believe).
Amazingly, after cleaning off the carbon with alcohol, the outfit still
works, albeit only from the mains on a 150V setting. When using the 130V
setting, I hear a little arcing in the plug. I can't clean in the crack
itself.
The PSU still works fine from the battery, but I won't be powering the TX
that way until I can come up with a fix.
Does anyone know where I might find a replacement plug and cord for the 109
TX? Failing that, does anyone know where I might find a plug matching the
TX plug, even if not original equipment? Failing that, has anyone any ideas
how I might solve my problem? Perhaps I could purchase someone's derelict
109 TX with a good power cord.
BTW, WRT the receiver sensitivity with the TX in and out of the antenna
circuit, I too notice a slight increase in signal strength with the TX out
of circuit. However, the operative word here is "slight".
- --
Cheers,
Chris F. Broadbent ( KC5VQL )
Date: Mon, 26 May 1997 00:42:04 -0700 (PDT)
From: Ken Gordon <keng@uidaho.edu>
Subject: Re: Bad GRC-109 Experience plus RX vs RX/TX Antenna Performance.
> BTW, WRT the receiver sensitivity with the TX in and out of the antenna
> circuit, I too notice a slight increase in signal strength with the TX out
> of circuit. However, the operative word here is "slight".
What frequencies did you check this on ?
According to the manual, for best receiver sensitivity on the LOWer
frequencies, one should use a separate antenna for the receiver.
Mine exhibited considerable difference in sensitivity on ALL frequencies.
Another receiver I am examining for a friend exhibits the same symptoms.
I am beginning to wonder if there is a problem with the RF input coils.
Ken W7EKB
Date: Mon, 26 May 1997 09:53:18 -0400 (EDT)
From: leeboo@ct.net (Leon Wiltsey)
Subject: REGENS
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>To: GB
>From: leeboo@ct.net (Leon Wiltsey)
>Subject: ? on regens
>Cc:
>Bcc:
>X-Attachments:
>
>Hi gang
>
>was working on my regen and made some
>interesting discoveries. most of the hum
>I was getting grom the det stage s due to
>the audio choke I was using for the load.
>Moving the choke around changed the amount
>of hum. So I put a small sig in and measured
>it on the scope. Replaced choke with 8k resister
>hum went down and sig went up in voltage
>about 30% Changed res to 22k and sig went up
> full 6db more hum did not change. raising value
>of res more did not raise sig out and just made
> me use more screen voltage to get it to osc.
> Sens went up with sig out with load of 22k.
>Why then do most all regen schematics call
>for a audio choke load on det. As far as I can see
>they causwe hum without any other advantages
>except when you have a low amount of b+ to work
>with. Am running 125v on plate and it osc at about
>15v on screen.
>
>hope someone with much knowledge of regens
>knows the answer.
>
a
68 yr old semidisabled senior
(stroke got my balance & hand to eye coordination)
ham agn as KF4RCL TECK+ (MUCH HAPPINESS)
BUILD MOST OF MY STATION EQUIP
(tubes that is no SOLID STATE)
Leon B Wiltsey (Lee)
4600 Lake Haven BLVD.
Sebring, Fl. 33872
SEBRING FL. THAT WONDERFUL PLACE WHERE THERE IS NO QRM
FROM ANYTHING LOCAL
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Date: Sun, 25 May 1997 22:15:47 -0400 (EDT)
Subject: ? on regens
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To: BOATANCHORS@sco.theporch.com
From: leeboo@ct.net (Leon Wiltsey)
Reply-to: leeboo@ct.net
Sender: owner-boatanchors@sco.theporch.com
68 yr old semidisabled senior
(stroke got my balance & hand to eye coordination)
ham agn as KF4RCL TECK+ (MUCH HAPPINESS)
BUILD MOST OF MY STATION EQUIP
(tubes that is no SOLID STATE)
Leon B Wiltsey (Lee)
4600 Lake Haven BLVD.
Sebring, Fl. 33872
SEBRING FL. THAT WONDERFUL PLACE WHERE THERE IS NO QRM
FROM ANYTHING LOCAL
Date: Mon, 26 May 1997 13:25:06 EDT
From: kb9iua@juno.com (Kevin L Anderson)
Subject: Great List -- Thanks
Just a brief note of thanks to all who contribute
to the Glowbugs list (I read by digest). It reminds
me much of how boatanchors used to be four or
so years ago when it first started and I was a
subscriber. Keep up the good work, and I will
keep on lurking and learning. Just the elmers
I need!
Cheers/73. Kevin Anderson, Glowbugs/BA-list/QRP-L
* * * * * * * * * * * * * * * * * * * * * * *
Kevin Anderson, KB9IUA, Rock Island IL USA
kb9iua@juno.com or kla@helios.augustana.edu
work: anderson@ncrsun1.ncr.usace.army.mil
* * * * * * * * * * * * * * * * * * * * * * *
Date: Mon, 26 May 1997 23:03:25 -0500
From: "Daniel L. Kerl" <dlkerl@ro.com>
Subject: Re: Circuit Board Designers?
I've had good luck using the Protel Easytrax freeware. It'll do
four layers and runs under MSDOS. You can export different
plot formats including Gerber and Postscript. Most PC houses
can handle the Gerber photoplotter format. Download from
http://www.protel.com/download.htm
Dan Kerl
dlkerl@ro.com
End of glowbugs V1 #43
**********************
Created by Steve Modena, AB4EL
Comments and suggestions to modena@SunSITE.unc.edu