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previous: Casey4s RG,Thanks for the s... -- 6/5/2000 4:21 AM View Thread

Re: Runaway Bias

6/5/2000 3:25 PM
Gil Ayan
Re: Runaway Bias
"(4) Yes, I can get from -38.5 to -41.6 by turning the 25k pot.  
(5) The tubes are good, NOS, TV-7 tested, but I put a known good used pair of 6L6's in ther just to be sure, they biased at around 160 ma :o(  
With the plates at 535V like you have, 6L6s will most likley require around -55VDC to work well. You need to have a bias range of about -35 to -65 if you want to accommodate all kinds of tubes... so what you may want to do is scale back the resistive elements in your bias supply (excpet the pot), or... increase the pot value (however, typically, unless you use trimmers, nice chassis-mounted bias type pots come in only a couple of values).  
Good luck,  

Casey4s Re: Runaway Bias (driving me nutz) -- 6/5/2000 7:44 PM