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Author Topic: Can anyone help me to identify this homebrew xmitter?  (Read 3503 times)
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KC9KEP
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« on: October 29, 2012, 02:25:42 PM »

Hello all,

I've recently purchased this homebrew transmitter.  It appears to feature a lot of "iron", but I don't know what the builders source for a schematic was (if any).

It features a single 6146 tube (inside the sub enclosure) some unidentifyable 9-pin miniature tube (it may be a 6GH8) and two 6DQ6's.

I suspect that the 9-pin is an audio mic pre-amp, the two 6DQ6's may be audio drivers and the 6146 the final output.  I see no oscillator so my guess is that he used an external VFO.

I'm thinking that this may be an AM mode transmitter.  Is this transmitter design familiar to anyone?  (Links to photographs follow)

Thanks & 73
KC9KEP

http://www.bignick.net/temp/a.JPG
http://www.bignick.net/temp/n.JPG
http://www.bignick.net/temp/m.JPG
http://www.bignick.net/temp/h.JPG
http://www.bignick.net/temp/d.JPG
http://www.bignick.net/temp/c.JPG
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W7TFO
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« Reply #1 on: October 29, 2012, 02:36:20 PM »

Decent economy construction technique, harkens back to the TVI days with the shielding and tube types.

It doesn't follow any of the period designs in either ARRL or Jones books from the period '50 thru '65, but looks to use many of the proven circuits in those books.

It is good to see an 'independent' design that worked.

73DG
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Just pacing the Farady cage...
kb3ouk
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« Reply #2 on: October 29, 2012, 02:41:58 PM »

That's a TCS modulation transformer.
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K9PNP
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« Reply #3 on: October 29, 2012, 06:38:45 PM »

Looks to me like the single 6146 amplifier which was, IIRC, in the ARRL Handbook late 50's or early 60's.  Looks similar to the amp from Aug 56 QST by Lew McCoy.  Of course, these weren't modulated.  Just wondering if this one is plate modulated since the 6146 amp is in the 60-80 watt range and the mod iron says 20 watts.  But since it is a Collins by Chicago Transformer, that is probably the CCS rating.  The 6DQ6's should be capable of 50-60 watts or so audio, since they were used at 25-30 watts input for RF.
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73,  Mitch

Since 1958. There still is nothing like tubes to keep your coffee warm in the shack.

Vulcan Theory of Troubleshooting:  Once you have eliminated the impossible, whatever remains, however improbable, must be the truth.
K9PNP
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« Reply #4 on: November 01, 2012, 06:55:30 PM »

Found what I was looking for in the 1962 ARRL Handbook.  Pg 182 is "A 90-watt all purpose amplifier".  Pg 271 is "25 watt modulator using push-pull 6BQ6GT's".  These look to be similar to your rig when put together.
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73,  Mitch

Since 1958. There still is nothing like tubes to keep your coffee warm in the shack.

Vulcan Theory of Troubleshooting:  Once you have eliminated the impossible, whatever remains, however improbable, must be the truth.
KM1H
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« Reply #5 on: November 03, 2012, 09:48:24 PM »

It looks more like Mc Coy's Novice Gallon 2 tube TX and then a later article added the modulator for when the Novice got his General. Both were QST and HB published.

Carl
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