Subject: glowbugs V1 #223
glowbugs Wednesday, January 14 1998 Volume 01 : Number 223
Date: Tue, 13 Jan 98 10:42:09 CST
From: "Mark Dittmar" <Mark_Dittmar@maxtor.com>
Subject: 7044 tube
Hello all-
I have recently found a copious and cheap supply of 7044 tubes, a
twin triode according to my tube manual, using either 6.3 VAC or 12 VAC
for filaments depending on wiring config. Is this tube a DIRECT
substitution for any other twin triodes, like a 12AT7, 12AX7, 12AU7, etc
?
Thanks & 73,
Mark Dittmat
AB0CW
Date: Tue, 13 Jan 1998 22:33:52 -0800
From: "Paul Carreiro, N6EV" <n6ev@badger1.net>
Subject: Glowbug using 50HC6?
Hi Glowbugers...
I picked up a small glowbug rig for $2 at our local swap a few weeks ago.
It uses a 50HC6 along with some other unknown missing octal type tube
(rectifier perhaps). This appears to be one of those direct AC rigs as there
is no transformer.
The 50HC6 sparks a braincell of memory about some glowbug rig using this tube,
but can't find a schematic or reference to it in my archive.
Does anyone remember such a rig? It's a crystal controlled rig. Any
schematic
available? Anyone know what the mystery tube is?
Next step would be trace out the schematic (a real bear because of the tight
construction), or part it out.
Thanks for the help.
73/ZUT!
Paul N6EV
P.S. Check out my web site for recently uploaded pics of my station /
boatanchors.
Paul F. Carreiro - N6EV - ex-N6HCS - El Camino Village, CA
mailto:n6ev@badger1.net - http://www.qsl.net/n6ev/
QRP - Boatanchors - Glowbugs - Mobile CW - QRQ +45WPM - ZUT!
NorCal #367 - QRP-L #236 - QRP ARCI #8885 - FISTS #1407
SCQS #1 - Southern California QRP Society - WQ6RP
Zuni Loop Mountain Expeditionary Force (QRP Field Day) - K6ZNI
Date: Wed, 14 Jan 1998 08:53:50 -0700
From: Dexter Francis <cwest@xmission.com>
Subject: Re: 7044 tube
Mark -
The 7044 is a "computer rated" medium-mu twin triode, with
a 9H pinout, the same as a 5687, but not the 12AX7.
The 12AT7/X7/Y7 is base 9A.
9A = PT2, GT2, KT2, HT2, HT1, PT1, GT1, KT1, HM
9H = PT2, GT2, KT2, H, H, KT1, GT1, HM, PT1
The bias/plate current curves are probably not the same
as a 12AX7, judging form the tabulated data in the RC-29
databook.
- -df
- ----------------------------------------------------
Need to Buy or Sell Tubes, Parts or BA Gear?
Visit our Web site at http://www.xmission.com/~cwest/
e-mail to: tubes@usa.net -or- cwest@xmission.com
P.O. Box 22443, Salt Lake City, Utah 84122
Date: Wed, 14 Jan 1998 11:29:18 EST
From: EWoodman <EWoodman@aol.com>
Subject: Xfmr and Choke Rewinding
I've had an old aircraft battery charger kicking around for a few years. I
finally
decided to tear into it and see if I could salvage any goodies. What I've got
is a 56V CT 40 Amp (that's right 40 amps!) power transformer and a BIG filter
choke. Now seeing as both of these are open frame construction, it seems to me
that I should be able to do some rewinding. I'd like to rewind the secondary
on the power transformer into a hefty center tapped filament transformer and
strip the core and rewind the choke to use as modulation reactor (large value
choke) for Heising modulation. I've never done this before but have read in
several old books that it isn't that difficult (or so they say!). Anyone have
any pointers before I dig in and screw something up?
(Such as type of wire, material to use between winding layers, etc.) Or should
I just give up and find someone who can use them as is for some project before
I ruin them?
Tnx and 73 Eric KA1YRV
Date: Wed, 14 Jan 1998 12:17:10 -0500
From: "Ornitz, Barry L" <ornitz@eastman.com>
Subject: RE: Xfmr and Choke Rewinding
Eric, KA1YRV, wrote:
>I've had an old aircraft battery charger kicking around for a few years. I
>finally decided to tear into it and see if I could salvage any goodies. What
>I've got is a 56V CT 40 Amp (that's right 40 amps!) power transformer and a
>BIG filter choke. Now seeing as both of these are open frame construction, it
>seems to me that I should be able to do some rewinding. I'd like to rewind
>the secondary on the power transformer into a hefty center tapped filament
>transformer and
>strip the core and rewind the choke to use as modulation reactor (large value
>choke) for Heising modulation. I've never done this before but have read in
>several old books that it isn't that difficult (or so they say!). Anyone
>have any pointers before I dig in and screw something up?
>(Such as type of wire, material to use between winding layers, etc.) Or
>should I just give up and find someone who can use them as is for some
>project before I ruin them?
>
>Rewinding the power transformer as a really BIG filament transformer should
>be quite easy. Winding a high inductance choke, for use at high voltage DC
>such as a modulation choke, is not nearly as simple. Finding small gauge
>enameled copper wire is difficult enough, as is finding proper insulation
>materials. Unless you have infinite patience, you will need a lathe or
>winding machine. There is considerable skill involved in this - it is not
>the job for a beginner. Start with a low voltage transformer with large
>gauge wire first to learn on before trying to do anything with high voltage.
>
>My suggestion is to use the transformer and choke, as is, in a full-wave
>center-tap circuit with choke input. Your output voltage will be about 24 to
>25 volts (at 40 amps), perfect for powering many military surplus rigs. Your
>supply should do very well, even with an ART-13 to power. If the existing
>unit has selenium rectifiers, replace them with proper heat-sinked silicon
>diodes. A really big electrolytic capacitor for the output is not very
>expensive. Alternately a small pair of 12 volt batteries in series can be
>used in place of the electrolytic.
>
>It has been a long time since I have seen a QST article on rewinding
>transformers - probably the late 1960's. Find one of these articles if you
>can before starting the project. Just remember the voltages involved and be
>careful. Shorts in a high voltage choke are NOT pretty!.
>
> 73, Barry L. Ornitz WA4VZQ ornitz@tricon.net
End of glowbugs V1 #223
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