[AMRadio] Filament Voltage

[Dan Hall]

Greetings:

I have very poor filament voltage regulation on the Gates BC1-J. The
transmitter is designed with a rheostat on the front panel to set the
voltage to 10 volts. Of course it is designed to run around the clock. If I
set the voltage at standby to 10 (filaments glowing, all plate voltages off)
when I move to transmit the filament voltage drops to just over 9V. The best
efficiency is around 63% (2075 VDC, .380 A and 500 watts out). Leaving
everything else alone I then crank the filament voltage up to 10 volts and
get 73% (2050 VDC .400 A and 600 watts out).

The problem is that when I key up, the filament voltage soars to about 10.75
volts.

Now, should I run the tubes at 9 volts in transmit and 10 at standby or 10
volts in transmit and 10.75 at standby?

Thanks
Dan
KJ7FX