[Amps] regulated screen supply

[DEHAYS Dominique]

Hello ,

I'm looking for ideas.... I am using a QBL5-3500 amplifier on 2m. Untill 
now , I have been using unregulated screen power supply with quite good 
success , but since I've moved to a new place , my mains voltage is higher 
than previously and my screen voltage went up to 1000v ( instead of 800v 
recommanded for that tube) . Off course , it is possible to use a small 
variac on the transformer primary , but a better idea would be to design 
and build a 800V screen regulator , if possible , an high performance 
design , like the one designed by GM3SEK in his famous " Tetrode Boards" , 
with the various protections needed..
But the tube is a little bit greedy ( or GRIDdy :0))

Screen voltage is 800V WG2 power is 100W maximum , so screen current can 
go up to 120ma during normal operation. There is nothing said in the tube 
data sheet about negative screen current , but there is no reason why it 
cannot occur.
So I am looking for a design able to statisfy my needs. Maybe the GM3SEK 
can be modified to run with that tube?

73 Dom/F6DRO