Daily GLOWBUGS
Digest: V1 #46
via AB4EL Web Digests @ SunSITE
Purpose: building and operating vacuum tube-based QRP rigs
Subject: glowbugs V1 #46
glowbugs Friday, May 30 1997 Volume 01 : Number 046
Date: Thu, 29 May 1997 18:53:49 -0500 (CDT)
From: Dave <gekko95@ix.netcom.com>
Subject: Silly signature line...
To slow the tide of queries to me why my sig line says
what it said in my last post (AES Update)...
Part of an inside joke (eh, McAulay?) from another
email. Forgot to clear it outta there.
To those who emailed me about it, thar's yer answer, mate
:)
Dave
Note the conspicuous absence of a signature line
Date: Fri, 30 May 1997 02:02:56 +0000
From: "Brian Carling, Radio AF4K" <bry@mnsinc.com>
Subject: Re: Antigue Electronic Supply
For information about AES, try:
http://www.mnsinc.com/bry/hamlynx/hamdealr.htm
On 29 May 97 at 7:31, Adam Liette spoke about Antigue Electronic
Supply and said:
>
> I know I could just call them and it would be faster, but
> does AES (Arizona) have a webpage and/or e-mail?
> Would be very helpful in finding their prices.
>
> TNX
> Adam Liette
> URL:kb8ydx.base.org
> E-Mail:kb8ydx@geocities.com
>
> --------- --------
> / |
> / ----| / ___
> / | |___
> / -------- ___|
> ..._._
>
****************************************************
*** 73 from Radio AF4K/G3XLQ Gaithersburg, MD USA *
** E-mail to: bry@mnsinc.com *
*** See the interesting ham radio resources at: *
** http://www.mnsinc.com/bry/ *
****************************************************
Date: Fri, 30 May 1997 09:13:06 +0100
From: BOB DUCKWORTH <bob@atl.org>
Subject: space charge tubes scarce?
I wasn't paying attention, 1 demerit tallied.
How scarce are these 12K5 etc?
- -bob
Date: Fri, 30 May 1997 09:07:59 -0700
From: "R. Eric Sluder" <sludere@gte.net>
Subject: FT243 to HC-6?
Got a question for the group that has probably already been addressed
before, but here it is again. Was there an adapter ever made to convert
FT-243 to HC-6 pin spacing? I got my rocks from Phoenix xtals and want
to use them in my DX-60 as well as my DX-20. I'd like to know before
hunting for one at the next hamfest. Or, if you know of any homebrew
methods? Any enlightenment would be appreciated.
73,
Eric
- --
~~~~~~~~~~~~~~~~~~~~~~~~~~
R. Eric Sluder, KB9BGS
3339 Eden Way
Carmel, IN 46033-3070 USA
<><
~~~~~~~~~~~~~~~~~~~~~~~~~~
Date: Fri, 30 May 1997 10:08:50 +0000
From: "Brian Carling, Radio AF4K" <bry@mnsinc.com>
Subject: Re: "Autotransformer modulation"
Somemore comments from Dave, G3UUR on this theme:
Going back to the autotransformer modulation, the
problem with single-ended class 'A' modulators is the
power dissipation required in the modulator tubes. For
instance, to modulate 100W DC input to the PA you
require 50W of audio and you can only get about 12W
from each of four 807s running at 25W input in class
'A'. The peaks of modulation may just reach 100% if
you're lucky. Five tubes in parallel in the modulator
would be better as it would give some margin for
transformer losses, etc. A push-pull class 'B'
modulator with two 807s could give enough output for
100% modulating 150W input and the power consumption
would be little more than that required for two 807s in
class 'A' which could just about modulate a DC input of
50W. Push-pull class 'B' is a must for the higher power
levels. The autotransformer trick is OK for rigs of up
to about 25W DC input, but above that you pay in size
and power for the economy of the modulation
transformer. I like to use it for rigs like a single
6BW6 modulating a single 6BW6 at 10W DC input or an
EL34 or 807 modulating a 2E26 or 807 running at 25W DC
input. I have tried parallel class 'A' modulators, but
they become big and very hot as you try to go for more
and more RF power out. Using the existing amplifier
into another output transformer reversed (secondary to
primary) for the high impedance feed to the PA might be
a way round your problem if you can find a transformer
intended for a large enough DC component of current in
the original primary, which becomes the secondary of
the new arrangement and has the take the DC feed to the
PA stage.
================
BTW - I THIN K tht he means 6GW8 / ECL86 not 6BW8.
Bry
****************************************************
*** 73 from Radio AF4K/G3XLQ Gaithersburg, MD USA *
** E-mail to: bry@mnsinc.com *
*** See the interesting ham radio resources at: *
** http://www.mnsinc.com/bry/ *
****************************************************
Date: Fri, 30 May 1997 11:06:54 -0400
From: Ray LaRue <raylarue@gte.net>
Subject: "autotransformer modulation"
Didn't keep the original post, but I think you are talking about
"heising" modulation.
A brief discription is found in Bill Orr's "The Radio Handbook", 16th
edition, p 292. It is described as "the oldest system of plate
modulation. It usually consists of a class A audio amplifier, coupled
to the RF amplifier, by means of a modulation choke coil". "It is
sometimes known as "constant current" modulation. Because of the
effective 1:1 ratio of the coupling choke, it is impossible to obtain
100 % modulation unless the plate voltage to the modulated stage is
dropped slightly", by a resistor.
It's a technique used in the recent past by broadcast engineers, who
have had a failure of the regular class B, modulation transformer. They
have jury rigged a Heising system, while waiting for a new transformer.
73,
Ray, W4BYG
Date: Fri, 30 May 1997 10:00:44 -0600
From: mack@mails.imed.com (Ray Mack)
Subject: Re: FT243 to HC-6?
Eric:
I don't know of a conversion from FT-243 to HC-6. You can go
the other way really easy. Just demolish any Octal plug (a defunct
tube or a relay). Take 2 pins and solder them over the pins of the
HC6. There are several tricks to get the pins not to wiggle.
As you can guess from above, the pin spacing for HC 6 and
FT-243 is identical; the pins are just smaller on the HC6. What comes
to mind is to take a defunct HC6 and unsolder the can. Demolish an
octal socket and take 2 pins from the socket and solder them onto the
header for the HC6. Presto chango! Again this may not be especially
mechanically sound, but it should work.
Ray Mack
WD5IFS
mack@mails.imed.com
Friendswood (Houston), TX
______________________________ Reply Separator _________________________________
Subject: FT243 to HC-6?
Author: "R. Eric Sluder" <sludere@gte.net> at mails
Date: 5/30/97 9:07 AM
Got a question for the group that has probably already been addressed
before, but here it is again. Was there an adapter ever made to convert
FT-243 to HC-6 pin spacing? I got my rocks from Phoenix xtals and want
to use them in my DX-60 as well as my DX-20. I'd like to know before
hunting for one at the next hamfest. Or, if you know of any homebrew
methods? Any enlightenment would be appreciated.
Date: Fri, 30 May 1997 09:29:12 -0600 (MDT)
From: Art Winterbauer <art@comet.ucar.edu>
Subject: Re: FT243 to HC-6?
I've taken an old FT-243 xtal holder and soldered "legs" to each pin.
The legs were snapped from a paperclip. Then I plugged the converter
with legs into the HC-6 holder on the rig, and the FT-243 xtal into
the converter.
Sometimes, tho, the larger FT-243 xtal was too sluggish in the circuit
intended for the HC-6.
- --Art wa5oes
Date: Fri, 30 May 1997 09:10:56 -0700 (MST)
From: Jeff Duntemann <jeff.duntemann@coriolis.com>
Subject: Re: space charge tubes scarce?
At 09:13 AM 5/30/97 +0100, BOB DUCKWORTH wrote:
>I wasn't paying attention, 1 demerit tallied.
>How scarce are these 12K5 etc?
Not scarce at all, judging either by their prices (often under $2, even at
AES) or by difficulty of finding them, which has always (for me at least)
been nil. I keep thinking RCA must have made gazillions of them in the
late fifties, never imagining that transistors would wipe out the empty
state car radio almost completely by 1964 or so. AES has them, Alltronics
has them, most other tube dealers have them--often VERY cheap and often on
sale. What were they ever used in besides those ugly greasy AM car radios?
I find them in loose tube boxes at hamfests for a quarter. They're
definitely out there. Their only real downside is that they're current
hogs. The 12AL8 one-tube audio amp I have on the bench right now draws 900
mils cold, dropping to about 650 mils when the cathodes are up to temp. I
could well imagine that a five tube superhet might draw three amps
continuously--which is tough to get out of a wall wart, which was my
original concept. (I run 12V things like this off gel cells.)
- --73--
- --Jeff Duntemann KG7JF
Scottsdale, Arizona
Date: Fri, 30 May 1997 11:22:06 -0500 (CDT)
From: mjsilva@ix.netcom.com (michael silva)
Subject: Using switching PS to get B+ from 12v -- ideas?
Hi all,
I'm very interested in putting together a (semi) portable rig (current
plans are three 5EA8s (sic) for receiver, 6EA8 and 6AQ5 for
transmitter), and I'm thinking about how to get 300 or so volts out of
a car battery. I know the old way to do it, but does anybody know
enough about switching regulators to comment on the difficulty of doing
it that way? Any parts or manufacturers recommendations?
73,
Mike, KK6GM
Date: Fri, 30 May 1997 13:00:28 -0400
From: Adam Liette <kb8ydx@geocities.com>
Subject: Can I do anything with these?
I have the following tubes. Can I use any in a transmitter?
6BH6
6U8A
12AU7A
6CL6
12AT7/ECC81
12AX7
NOTE: The 4th one is 6CL6 NOT 6L6. Just letting everyone know before they
just about faint like I did. I was looking for schematics and thought I
didn't have that type of tube, which I didn't.
All help appreciated!
TNX ES CUL
Adam Liette
URL:kb8ydx.base.org
E-Mail:kb8ydx@geocities.com
- --------- --------
/ |
/ ----| / ___
/ | |___
/ -------- ___|
..._._
Date: Fri, 30 May 1997 14:20:44 -0400 (EDT)
From: rdkeys@csemail.cropsci.ncsu.edu
Subject: Weekend BA/GB/CWist funzies.....yes/no?????
Well, the weekend is here, and I need another reality check.....
So, I will monitor 7050 and 3579 for activity, anytime after dark.
I will try to have the Hartley/Regen up on 3579, and Big Bertha/RAL
as backup. On 40 I will park the SRT-14/R-388.
Try any hour on the hour on either QRG anytime after dark.
The usual CQ BA call will suffice, with 0300Z reserved for the QRQ CWists
on 7050.
Hope to see some of you there.....
73/ZUT DE NA4G/Bob UP
Date: Fri, 30 May 1997 14:15:40 +0100
From: BOB DUCKWORTH <bob@atl.org>
Subject: Re: Using switching PS to get B+ from 12v -- ideas?
Junkbox swap time!
I've about a dozen Triad inverter transformers.
Complete with apps sheet or look in 67 handbook
at the mobile transceiver construction article.
600VDC and 300VDC (centertapped secondary) at 120mil total.
Two transistors, some diodes and caps, two bias resistors
and your set.
Don't know about switching other than it's like an
inverter with an autotransformer and some feedback
to vary pulse width as needed to maintain power at
voltage or current set point.
- -bob
michael silva wrote:
>
> Hi all,
>
> I'm very interested in putting together a (semi) portable rig (current
> plans are three 5EA8s (sic) for receiver, 6EA8 and 6AQ5 for
> transmitter), and I'm thinking about how to get 300 or so volts out of
> a car battery. I know the old way to do it, but does anybody know
> enough about switching regulators to comment on the difficulty of doing
> it that way? Any parts or manufacturers recommendations?
>
> 73,
> Mike, KK6GM
Date: Fri, 30 May 1997 13:38:36 -0500 (CDT)
From: Bob Roehrig <broehrig@admin.aurora.edu>
Subject: Re: Using switching PS to get B+ from 12v -- ideas?
On Fri, 30 May 1997, michael silva wrote:
> I'm very interested in putting together a (semi) portable rig (current
> plans are three 5EA8s (sic) for receiver, 6EA8 and 6AQ5 for
> transmitter), and I'm thinking about how to get 300 or so volts out of
> a car battery. I know the old way to do it, but does anybody know
> enough about switching regulators to comment on the difficulty of doing
> it that way? Any parts or manufacturers recommendations?
Look in some of the older ARRL handbooks. ARRL also had a "Mobile
Handbook" at one time too. You should find designs for transistorized
DC/DC converters. Most just use a pair of power transistors and a
torroidal transformer. It's kind of a replacement for the vibrator
supply. Triad made transformers specifically for this job. I built one
to replace the dynamotor in my old trunk mounted Motorola 80-D rig.
E-mail broehrig@admin.aurora.edu 73 de Bob, K9EUI
CIS: Data / Telecom Aurora University, Aurora, IL
630-844-4898 Fax 630-844-5530
Date: Fri, 30 May 1997 14:47:51 -0500
From: John Michael <MICHAEL@ecs.umass.edu>
Subject: Re: Can I do anything with these?
>I have the following tubes. Can I use any in a transmitter?
>6BH6
>6U8A
>12AU7A
>6CL6
>12AT7/ECC81
>12AX7
You can't really do much with these as PA tubes, I'm afraid Adam. The 6CL6
with a plate dissipation of around 7 watts is the heftiest of the bunch.
Of course anything you can get to oscillate can be used as an output tube if
you don't care how far you go. Anyone here used the 6CL6 in an exciter
stage? The 12AT/AU/AX tubes are all twin triodes, of various Gm. You could
use them in a mike preamp stage in a transmitter.
Best wishes,
John Michael michael@ecs.umass.edu
Date: Fri, 30 May 1997 14:10:20 -0500 (CDT)
From: mjsilva@ix.netcom.com (michael silva)
Subject: B+ from 12v -- torroid sources?
Yes, I do remember seeing articles about torroids used in inverters.
Even have a vague memory of an article on wrapping the core with glass
cloth and baking it in an oven...
So, where would a person look for such a torroid (wound or unwound)?
73,
Mike, KK6GM
Date: Fri, 30 May 1997 15:43:48 -0500
From: Conard Murray <ws4s@InfoAve.Net>
Subject: BA swaplist info
----
From: Eugene Rippen <soundval@foothill.net>
To: baswaplist@foothill.net
Cc: soundval@foothill.net
Date: Friday, May 30, 1997 1:55 PM
Subject: 400 Subscribers & Thanks
>THANKS to brian Carling of HEATH@listserv.temp.gov
>and thTHANKS to the Administrator of rec.radio.swap
>who this week both posted notices of this baswaplist
>reflector: baswaplist has about 70 new subscribers.
>
>As of this time there are now 400 SUBSCRIBERS
>
>For our most recent new ones the Welcom message follows:
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>
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>It is located at: baswaplist@foothill.net
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>
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>
Date: Fri, 30 May 1997 13:48:49 -0700 (PDT)
From: Ken Gordon <keng@uidaho.edu>
Subject: Re: FT243 to HC-6?
> Got a question for the group that has probably already been addressed
> before, but here it is again. Was there an adapter ever made to convert
> FT-243 to HC-6 pin spacing? I got my rocks from Phoenix xtals and want
> to use them in my DX-60 as well as my DX-20. I'd like to know before
> hunting for one at the next hamfest. Or, if you know of any homebrew
> methods? Any enlightenment would be appreciated.
Carefully cut the pins off an old octal socket and push them over the HC-6
pins. Viola! Perfect fit.
Ken W7EKB
Date: Fri, 30 May 1997 17:30:04 -0400
From: Adam Liette <kb8ydx@geocities.com>
Subject: QRP Transmitter
Hello again. I found a 6AQ5A I might use fer a transmitter.
Got a schematic from W4FK's sight (TNX Bry). If I can find
all the stuff to put it together, think I'll try it.
Someone said something abt an xmtr with a 6L6 and a 6U8.
Anyone have the schematic somewhere?
TNX ES 73
Adam Liette
URL:kb8ydx.base.org
E-Mail:kb8ydx@geocities.com
- --------- --------
/ |
/ ----| / ___
/ | |___
/ -------- ___|
..._._
Date: Fri, 30 May 1997 16:45:32 -0600
From: mack@mails.imed.com (Ray Mack)
Subject: Re: Using switching PS to get B+ from 12v -- ideas?
Mike:
The old way to do it is OK as others have said. I might be
inclined to swap Bob Duckworth for one of his transformers. These
circuits usually run around 200 Hz and use a tape wound toroid. They
are self excited oscillators.
A tape wound toroid is made by taking a very long piece of
narrow, thin sheet steel and winding it like a flat spring into a
toroid. The toroid is then encapsulated in plastic of some sort. The
toroid is basically a normal power line transformer type core except
it is toroid shaped.
These circuits have *NO* regulation. They basically convert
the incoming voltage to a 50% duty cycle rectangular wave and use the
winding ratio to step up the voltage. If the input voltage drops, the
output voltage drops.
There are any number of circuits made by Maxim, Unitrode,
Motorola, and just about every other semiconductor manufacturer that
will provide for regulated DC-DC converters. These are basically the
same thing as the classic circuit except they use a master oscillator
and circuitry that varies the duty cycle to regulate the voltage out.
These also tend to run in the supersonic range so the whine problems
of the classic circuits are less. The size of the transformer is less
also. A transformer for a 50KHz converter at 200 Watts will weigh
less than a pound and fit in the palm of your hand.
You can make a more modern version of the classic circuit by
making a 50 KHz oscillator that drives a couple of IRF510 FET's in
push-pull driving a transformer wound on a mix 26 toroid or on a 3B5
pot core. Again, remember that you won't have any regulation in this
situation. The regulation is probably not a problem for a firebottle
rig.
Ray Mack
WD5IFS
mack@mails.imed.com
Friendswood (Houston), TX
______________________________ Reply Separator _________________________________
Subject: Using switching PS to get B+ from 12v -- ideas?
Author: mjsilva@ix.netcom.com (michael silva) at mails
Date: 5/30/97 11:22 AM
Hi all,
I'm very interested in putting together a (semi) portable rig (current
plans are three 5EA8s (sic) for receiver, 6EA8 and 6AQ5 for
transmitter), and I'm thinking about how to get 300 or so volts out of
a car battery. I know the old way to do it, but does anybody know
enough about switching regulators to comment on the difficulty of doing
it that way? Any parts or manufacturers recommendations?
Date: Fri, 30 May 1997 18:39:28 +0000
From: "Brian Carling, Radio AF4K" <bry@mnsinc.com>
Subject: Re: Using switching PS to get B+ from 12v -- ideas?
Bob & Mike - caution when using SWITCHING POWER SUPPLIES!
Some of them REALLY do cause a LOT of hash in the receiver!
The Lambda ones that I tried some years ago did, anyway!
ZUT! - Bry
On 30 May 97 at 14:15, BOB DUCKWORTH spoke about Re: Using switching
PS to get B+ fr and said:
> Junkbox swap time!
> I've about a dozen Triad inverter transformers.
> Complete with apps sheet or look in 67 handbook
> at the mobile transceiver construction article.
> 600VDC and 300VDC (centertapped secondary) at 120mil total.
> Two transistors, some diodes and caps, two bias resistors
> and your set.
> Don't know about switching other than it's like an
> inverter with an autotransformer and some feedback
> to vary pulse width as needed to maintain power at
> voltage or current set point.
> -bob
>
>
> michael silva wrote:
> >
> > Hi all,
> >
> > I'm very interested in putting together a (semi) portable rig
> > (current plans are three 5EA8s (sic) for receiver, 6EA8 and 6AQ5
> > for transmitter), and I'm thinking about how to get 300 or so
> > volts out of a car battery. I know the old way to do it, but does
> > anybody know enough about switching regulators to comment on the
> > difficulty of doing it that way? Any parts or manufacturers
> > recommendations?
> >
> > 73,
> > Mike, KK6GM
>
****************************************************
*** 73 from Radio AF4K/G3XLQ Gaithersburg, MD USA *
** E-mail to: bry@mnsinc.com *
*** See the interesting ham radio resources at: *
** http://www.mnsinc.com/bry/ *
****************************************************
Date: Fri, 30 May 1997 18:39:29 +0000
From: "Brian Carling, Radio AF4K" <bry@mnsinc.com>
Subject: Re: Can I do anything with these?
Adam, you can use ALL of those tubes in a transmitter!
None of them will get you above the QRP 5 watt "full gallon" level
though! There are some excellent designs out for transmitters using
the 6U8.
6CL6 is a common driver or VFO tube used in small xmtrs too!
73 - Bry, AF4K
On 30 May 97 at 13:00, Adam Liette spoke about Can I do anything with
these? and said:
> 12AX7
****************************************************
*** 73 from Radio AF4K/G3XLQ Gaithersburg, MD USA *
** E-mail to: bry@mnsinc.com *
*** See the interesting ham radio resources at: *
** http://www.mnsinc.com/bry/ *
****************************************************
Date: Fri, 30 May 1997 16:15:48 -0700
From: "A Redshirt" <occupant@ns.net>
Subject: On switching P.S. to get B+ from 12VDC...
Folks:
As I threw away about fifteen G.E. MASTR PRO mobile
power supplies last month, I though "I bet SOMEBODY...."
Anyway, these things power the last of the tube-final type
commercial FM two way stuff that Generous Eccentric
produced. The torroid xfmr is about at big around as a Coke
can; maybe 1 1/2' tall, and the unit would cause tubes like
5894s and 8072s to pound out up to one hundred watts
(with two transformers; the single xfmr supply was good
for 25-40 watts out the hole). Remember that this is ICAS
rating.
These power supplies ought to be available at most junk
meets...er, Swap Fests for about $0.05 a pound. Two
Phillips head screws, one connector, and the jewel is in
your hand. Torroid, xsistors, filter caps, everything one
needs for the ideal B.A. mobile! One piece. Heat sink
built in. Standard made-in-USA parts used throughout.
Designed for PTT operation. Stack those Torroids, grab
that 807, and kick some 'phone BUTT while mobile!!
See also your local VHF/UHF FM types. Say "GE MASTR
PRO mobile supplies wanted!", and stand back. There
were literally *millions* of these things produced, and
they would be excellent for the mobile B.A. amateur....
And the FM guys will never realize what the resolute
B.A.-type can accomplish with something like this that
has little value to them...
(I have specs, pinouts, blah blah blah, if there is sufficient
interest...)
de John
occupant@ns.net
Date: Fri, 30 May 1997 16:32:28 -0700 (PDT)
From: Ken Gordon <keng@uidaho.edu>
Subject: Re: Can I do anything with these?
>
> I have the following tubes. Can I use any in a transmitter?
>
> 6BH6
Sharp cutoff pentode. Could probably use this one as very low power
transmitter. Plate resistance is 1.4 meg. Should make a decent crystal
oscillator or VFO tube. Suppressor is separate from cathode.
> 6U8A
9 pin miniature. Medium mu triode and sharp cutoff pentode. Would make a
good triode oscillator with following pentode amp. Low power. About 2.5
watts in class A. More in class C.
> 12AU7A
Medium mu dual triode. Could be used as a low power transmitter.
> 6CL6
Pentode. Pretty decent power for its size, about 3 watts. Used as driver
in many small transmitters.
> 12AT7/ECC81
High mu dual triode. Pretty small but would make a pretty good VFO/Cathode
follower.
> 12AX7
High mu dual triode. Could run 7.5 watts as class B push-pull amp. if you
push it a bit.
Hope this is what you are looking for.
Ken W7EKB
Date: Fri, 30 May 1997 20:06:39 -0700 (MST)
From: Chris Trask <ctrask@primenet.com>
Subject: Re: Can I do anything with these?
On Fri, 30 May 1997, Ken Gordon wrote:
>
> I have the following tubes. Can I use any in a transmitter?
>
> 6BH6
> 6U8A
> 12AU7A
> 6CL6
> 12AT7/ECC81
> 12AX7
>
Actually, I can see a complete QRP transceiver here, with a
buffered crystal oscillator in the transmitter and a rather nice regen
or direct conversion receiver.
I gotta go.
Regards,
Chris
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End of glowbugs V1 #46
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