I have a late 60's twin that I have reverted to AB763. I have a TAD quad bias meter. I can not get the bias current (using adjust pot) any higher than about 25 mA. My rail voltage is 457VDC so charts say I can go as high as 47 mA. I have dbbl checked my conversion to AB763 and seems ok. Can anyone give assistance or guidance?
Thank you for your time.