[AMPS] screen voltage supply

[Rich Measures]

>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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