[Milsurplus] [ARC5] Navy GP-7 Transmitter Connectors Available

[Mike Hanz]

On 12/21/2010 2:34 PM, Joseph Pinner wrote:
> Can you run a GP-7 or TBW on 400 cycle power?

Sadly, no.  There simply isn't enough iron in the power transformers to 
support the lower frequency at the power level required of the 
transformers.  You also have the problem of keying the set in CW mode 
with a lower line frequency, which in theory would require larger 
filtering capacitors to maintain the same ripple specification.  
However, there are a variety of lab inverters that can be tuned upward 
to 800Hz.  My favorite is the older Behlman series like the 100-C and 
100-AS, though you could probably squeak by with a 75-C or 75-AS at 
750VA.  They don't usually bring as high a price as the later ones with 
a digital meter, but still provide a kilowatt with less than 1/2% 
distortion.  You have to have patience and keep looking - the ones on 
ebay at the moment all suffer from the overpriced buy-it-now problem, 
but occasionally you will see one appear for a lot less.  Repair is 
fairly easy - the older ones are all discrete component designs and only 
uses any chips in the small oscillator drawer, IIRC.

Vy 73,
Mike  KC4TOS