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previous: Carlos I've just had a look at... -- 4/28/2000 7:37 PM View Thread

Re: Power Scaling in London Power amps

4/28/2000 8:43 PM
JaySGRe: Power Scaling in London Power amps
I think it's done with a custom PT which has a variac-like  
secondary section. Minimum might then generate 300Vdc and  
maximum might generate 450V. The bias runs off of a  
tracking voltage regulator scheme. Filament voltage(s) don't  
change with level, so all is well there.  
I built an amp which didn't put out the power I expected, so I added  
a 60V DC power supply to jack up B+. Bias switches on a different  
section of a DPDT. I don't touch it with the amp on, whereas the  
built-in-variac would work that way.