[AMRadio] Re: 450T amp

[D. Chester]

I wouldn't run the tube filament at half voltage.  That will shorten the 
tube life just as much as too much voltage.

The 6C21 is rated at some oddball filament voltage like 8.2 volts.  But 
that's for radar pulse modulator service.  The tube is very similar to a 
450TH or TL, but the filament voltage is boosted above normal to give it 
exceptionally high peak emission capability.  The trade-off is shortened 
tube life.  In normal radio transmitter service it should be run at 7.5 
volts.

Don

k4kyv