> Hi Douglas this is a very bad idea. The IMD performance of any tetrode
> is dependant on good screen voltage regulation. The dynamic regulation
That 's true.
> of the plate supply is pretty bad and this obviously causes problems
> with screen regulation if a string of zeners are used.
Why? There is no reason it should cause problems if you wrap
around the zeners with few transistors.
The series resistance of a string of zeners might be too large
compared to the dynamic resistance of the screen, but if you have
enough voltage feeding the shunt regulator (at least twice the
screen voltage under full load) to properly current limit the screen
the zeners won't waddle around enough to hurt.
Just don't use zeners as the shunting device. Use some transistors
so the current gain lowers the shunt impedance. That way you can
use low power zeners, and regulation is good.
John Nelson
> GW4FRX wrote some excellent articles on this in the 80s.John frequents
> this forum so he may wish to comment.Meanwhile try this link for a
> solution http://www.ifwtech.com/g3sek/boards/tetrode/tetrode-1.htm and
> some background info.
>
> Regards
>
> Conrad Farlow G0RUZ
>
>
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73, Tom W8JI
W8JI@contesting.com
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