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[AMPS] Screen regulator circuit needed

To: <amps@contesting.com>
Subject: [AMPS] Screen regulator circuit needed
From: measures@vc.net (Rich Measures)
Date: Sun, 15 Nov 1998 05:32:58 -0800
>
>I'm wrestling with trying to get a couple of 811s and a string of VR tubes
>working as a regulator on a 1KV screen supply for a 4-1000 in AB1 (early 60s
>handbook circuit). 

?  One needs triodes with a Mu of under 5 for pass regulator service.  .

>I picked this circuit because I had the 811s. So far I've
>succeeded in building a nifty 200W or so LF oscillator (big surprise).
>
>I've looked at the G3SEK circuit & Ian says it won't stretch to 1KV.  I have
>a couple of other circuits I could try but I'm without a handy supply of low
>mu triodes (60s vintage handbook ckts).
>
>Anybody have any pointers to other circuits or articles?  ....

?  Bipolar transistors have a secondary-breakdown problem which makes 
them problematic in HV pass regulator service.  Power FETs are virtually 
immune to secondary-breakdown.  .  From my experiences, National 
Semiconductor's 723-based "positive floating regulator" circuit (using 
FET pass transistors) is good for regulating screen potentials.    2000v 
regulated output is practical with 600v-rated FET pass transistors.    
Since FETs operate with zero gate current, paralleling FETs for more 
current is easy.  .  On my Web site, there is a diagram and an article 
about this regulator.   My version of National's  "positive floating 
regulator" circuit is short-circuit proof and RF proof.  
-  later, Bill.

Rich. Measures.,www.vcnet.com/measures, 805.386.3734


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