[Boatanchors] Re: FS: TMC GPR-750 TAC-1 Tuner

[Robert R. Kerr]

I have a TAC-1.  It does look a lot like the BC-939, except it has two 
thermocouple line current meters at the top of the front panel - one for 
each side of a balanced line.  Can be used to feed either balanced or 
unbalanced lines.  The case has a pocket on the side for a reference 
table giving settings for the switches and counter dials for various 
frequencies from 2 to 30 MHz, but I tune mine initially by listening to 
the receiver noise amplitude.  There's a big fixed vacuum capacitor that 
can be clipped in parallel with the enormous butterfly variable 
capacitor at the low end of the frequency range.  I presume it could be 
used on 160 M if a larger fixed cap could be found.  I think a 1kW 
rating would be conservative, judging by the size of components inside.
The thermocouples for the meters on mine have burned out.  I think they 
weren't sealed well and the thermocouple junctions corroded; resistance 
increased; overheated and fried with high current - so they had to be 
bypassed.

Bob
WB4TGG

kd4e wrote:
> Plasma column?  Sounds like Star Trek!  :-)
>
> Does it look sort of like the BC-939?
>
> http://www.nj7p.org/millist/pic/bc-939a.jpg
> <http://www.nj7p.org/millist/pic/bc-939a.jpg>
>
> Do you know if the thermocouples are intact?
> I read several old posts that reported that the
> thermocouples are often found disassembled.
>
> I found this picture of the TMC GPR-750:
>
> http://www.jamminpower.com/eBay/TMC/GPR-750.html
> <http://www.jamminpower.com/eBay/TMC/GPR-750.html>
>
> Rated to about 500W 80-10M?
>
> Do you have an asking price in mind?
>
>> It is an overgrown Johnson matchbox that screws down to a TMC GPT-750
>> transmitter. This one was used to tune a RF source (think Hartley
>> oscillator using a 833) into a plasma column. Conard
>>
>> Conard Murray wrote:
>>> Hey Gang,
>>> Anyone need a TMC TAC-1 antenna tuner?
>>> 73,
>>> Conard, WS4S
>>
>> Inquiring minds want to know ... what is it?
>>
>> :-)
>>
>
>