hi again,
> I am courious if any
> one has grounded both grids in the 4cx400 and tried driving it like a
> triode?
several years ago eimac published an amateur radio application note about
this mode of operation (AS-1). the bottom line was ...
big glass tetrodes like 4-125, 4-250, 4-400, and 4-1000 work pretty
well as triodes, but the "high perveance" tetrodes like 4x150, 4x250, 4x350,
etc. *DON'T* work well as triodes. their control grids draw huge
currents... an example was given where the 4x150a had a grid current
of 1.3 a, screen current was 0.5 a, and the anode current was 0.8 a
at the peak of the driving voltage. this is not a "favorable
distribution" of cathode current. (it probably makes the 4x150a a
pretty neat flashbulb... remember them?)
there wasn't a 4cx400 at the time, but i'm betting they are pretty
poor triode amps!
73,
k6gt
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