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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 08:38:02 -0800
On 28 Jan 02, at 14:21, Steve Thompson wrote:

> Possibly or probably - I'll find out when I fire one up (anyone out
> there save me the bother?). They put -ve contours on the 4CX1600B so
> maybe they just cut and pasted the text. Happens all the time - or did
> when I worked in the semiconductor business. Anyhow, that's a
> digression. My guess is that any -ve current is likely to be small,
> and normal operation appears to run around 40mA +ve. It seemed to me
> to be wasteful dumping 40odd mA all the time in a shunt just to meet
> peak demand so I designed a series circuit, then got to thinking about
> protection which is where I came in.

When I was doing my 4cx800a/Dentron MLA2500 conversion, I got some 
plate curves from Svetlana in Russia.  I decided that -20ma was the 
most "wrong way" screen current I'd ever get for a single '800a... I 
diesigned my screen regulator with a zero signal 20ma drain (see "New 
life... QST, May 1996, if you want.)  In actual pretty heavy use 
(contesting) with varying antenna loads and driving conditions, I 
never noticed any more than about -5ma; when it's driven properly and 
loaded properly, +15 - 20 ma is what I see.  (All numbers are "DC" 
meter readings.  It's not that the tube doesn't EVER swing into 
negative screen current on RF anode current peaks... I don't monitor 
that.) 

73,

George Daughters, K6GT


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