Tube Amps / Music Electronics
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|12/11/1999 3:12 PM|
hey all, can anyone recommend any alternative
methods of reducing the "B+" coming outta' a
BF Bandmaster power tranny - besides the zener diode trick?
I installed 3 24volt 5 watt zeners in series off
the center tap and reduced the B+ from 452VDC to
about 396VDC -BUT- the darn 72volt bias tap circuit
behaved very weirdly .. using the standard 10K-L pot
and a 22K resistor from one side to pot chassis
ground the negative volrage available read from -31
to -56 vdc, but I could not get anything more than
7.6ma of bias current through the power tubes (4 6V6GT - in a 5F8-A Twin circuit), after removing the zeners,
the bias swing available was -67 to -28vdc and I easily
able to gewt about 22ma per tube- problem is I feel
like I am killing those poor 6V6'ers with aroung 452 volts on the plates. helllllllppppp
|Ken Gilbert Put the zeners back in.|
Dave H. You could put the Zeners in the pos... -- 12/13/1999 2:32 PM