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[AMPS] Shunt regulated high voltage psu

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Subject: [AMPS] Shunt regulated high voltage psu
From: gdaught6@leland.stanford.edu (George T. Daughters)
Date: Wed, 30 Jan 2002 12:08:07 -0800

Hi,

Rich wrote...

> //   Sounds good.  How did you protect the screen from loss of anode
> potential?.

This reminded me of a 4-65A amp (class C) that I built for 40m many 
years ago.  After installing a bigger fan (cooler is gooder) I hooked 
everything back up to the power supply, which was in a separate 
cabinet. 

Well, almost everything.  Not the anode supply; but the "stiff" 
screen supply was connected.

The first time I keyed up, the screen potential was applied, and the 
tube performed like one of the old focal-plane shutter type 
flashbulbs.  It gave off a very bright light, nearly white... none of 
that wussy orange color... for a fraction of a second (1/4? 1/2 
second?)and I was left with a 3-65A.  

It was an expensive show in a brief time. 

In my tetrode amplifiers since that time, screen voltage application 
always requires the presence of appropriate anode voltage (and 
appropriate control grid bias, as well!) whatever the method of 
screen regulation (or lack thereof.)

73, 
George Daughters, K6GT


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