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[Amps] Bias Zener Diodes In Parallel ?++

To: <amps@contesting.com>
Subject: [Amps] Bias Zener Diodes In Parallel ?++
From: W8JI@contesting.com (Tom Rauch)
Date: Fri, 19 Jul 2002 22:45:41 -0400
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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