[AMPS] Amp using 833A

[Peter Chadwick]

Tom says:

>I think this goes back to arguments in the past Peter, where Rich 
>felt that:
>
>Any positive grid to cathode potential = unacceptable distortion
>
>That equation isn't true in many if not most cases. The worse thing 
>about the 833 will be stability and the fact that drive power in GG 
>would be too high.

This is all very true. However, there is an anomaly in the argument in that in 
GG AB2, the grid does go positive with respect to the cathode. The reliance is 
on negative feedback to keep distortion down. Further, because the tube is 
either zero bias or can be biased with a zener, the bias supply can be made 
pretty stiff. Absolutely no reason why a stiff bias supply can't be used in 
grounded cathode, or for that matter some NFB too.

The drive power requirement is inherent in the fact that tubes for power 
oscillator use, especially where the load is very variable as in RF heating, are

for best performance, low mu devices.

But there are operation modes other than GG!

73

Peter G3RZP




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