Hi Bill - try using high voltage scan transistors from tv's. These are
rated at 1500V or more for Vceo. Should be available pretty cheaply, I paid
about $1 a piece a little while back. Use a smallish npn transistor to
drive the big one (tv scan transistors have low hfe's) and use a shunt
stabiliser circuit fed from about 1250 to 1500V via a suitable dropper
resistor. I used something similar a while back to stabilise the 750V for a
big tetrode.
John ZS5JF
-----Original Message-----
From: Bill Coleman <n2bc@ibm.net>
To: amps@contesting.com <amps@contesting.com>
To: <amps@contesting.com>
Date: Sunday, November 15, 1998 4:22 AM
Subject: [AMPS] Screen regulator circuit needed
>
>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). 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? If I'm going to
>have to buy parts (shudder), I may as well try something from the current
>decade!
>
>Thanks, Bill N2BC
>
>
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