>Has anyone tried tapping off of the B+ via a dropping resistor to provide
>screen voltage to a tetrode?
Sure. A dropping R and a zener string shunt screen-regulator is
preferred for smallish AB1 amplifiers with minimal screen current
requirements.
>If you only need a 100ma or less wouldn't this work? >With acceptable E
regulation?
Yes. However, if the anode supply was 9kV no-load (typical 8171), there
would be 900w of regulator circuit dissipation during receive. That's why
larger Class AB1 amplifiers usually use a series pass screen-regulator
with a c.20mA bleeder to handle reverse screen current instead of a zener
shunt regulator.
Rich---
R. L. Measures, 805-386-3734, AG6K
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