[Milsurplus] grc-9; am-66 amp power supply

[Richard Brunner]

Robert said:
"> I have the French manual (in English) on the amp and its dynamotor power
> supply.  I've often felt like kicking myself for not buying the hardware 
> years ago
> when Fair had them.  Don't know where they all went when Fair sold them 
> but
> none have ever turned up on any list that I know of."

Do not kick yourself, it isn't worth it.  I had one from Fair, and it has 
significant design deficiencies.  It gives a genuine 90 Watts output on CW, 
but the difference on CW between 10 or 15 Watts to 90 Watts is 
insignificant.  On AM the biasing on the final 2E22's suppressors for 
suppressor modulation is way too low, -40 volts, the same as in the GRC-9 
with 500 plate volts, and should be about -100 volts for 700 plate volts in 
the AM-66, so output only goes down about 10% when you switch from CW to AM 
when it should go down 75%, thus modulation is all downward.  To be fair it 
doesn't sound too bad, but it is poor design.  I think they knew what they 
had done, but built it anyway to meet design output requirementson AM. 
(FWIW, -40 volts on the suppressor for AM is too low for the GRC-9 too.) 
The AM-66 is designed for a whip, (wand) and half-wave antenna, and does not 
load well into a dipole.  Also the receive signals are back-coupled through 
the transmitter, and there is noticable attenuation.  I sold mine with no 
regrets.

Richard Brunner, AA1P