>
>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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