Hi Alex,
You can not properly cathode modulate a linear triode by varying
bias.
First... any modulated stage has to be heavily into in class C in
order to have linear modulation. You can't modulate it if it is
linear, at least not in any useful manner.
Second... varying bias in one triode stage alone, especially a GG
triode, would not cut the tube fully off. It would be impossible to
have 100% negative peaks because of feed through.
This is why AM transmitters use class C tubes heavily into cutoff,
and if the use cathode modulation they also modulate earlier stages
besides the class C PA, and why GG amps are never modulated without
modulating earlier stages as well.
> Here is an idea that one could use :)
> Instead ZENERS use a DC amplifier offset to the voltage you need for
> the proper tube biasing. Now you can add audio to it and you have
> created an XCELENT AM transmitter :)
73, Tom W8JI
W8JI@contesting.com
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