[Boatanchors] Pigmy Powerhouse PS

[Charlie Cheney]

Gents,

I picked up a Pigmy Powerhouse (QST, Oct. 58) at a flea market a while 
back but never put it on the air. I'd like to run it during SKN and 
future CRX. It works fine on the bench with a lab supply, VFO is quite 
stable. The lab supply is a Lambda that I can barely lift so it isn't 
much of a match for the Powerhouse. I'd like to use an AC-4 since the RX 
will be an R-2B. The AC-4 doesn't put out 150V but an OA2 took care of 
that. I may have to extend the range of the bias control to go negative 
enough to fully turn off the 5933 with nearly 700 volts on the plate but 
that's no problem either.

However, the tube complement is 2 x 5763 and 1 x 5933 and it's of course 
wired for 6.3V while the AC-4 puts out 12.6V.There's no room to replace 
the 5933 with a 1625. I considered an outboard filament xformer but that 
seems rather clumsy since it would need its own AC input. I could put 
the 5763's in series and use a dropping resistor for the 5933 but 
there's a lot of heat going into this small box anyway.

So my thought is to put a Schottky in series with the 12.6V and run the 
filaments on the half-wave-rectified but unfiltered AC. I'll lose a 
little in the forward bias of the diode but with line voltages running 
high anyway, the effective RMS should be high enough.

To save me a set of tubes, please tell me why this won't work!

Thanks and 73,

Charlie K1LDZ