06-06-2020, 10:55 PM
A. I built a pair of Dopplesondes with 5F6 preamps. All is operational except the fixed bias. As built, it had -20V B-. With Cathode bias switched in, B- was -340V. After trying lower R for the Bias supply I found with only 56k R, the bias was -94V with one set fixed and-56V with both sets fixed. I now have one 56k R and 22uF C dedicated per tube set. Both tube sets now have -56V max bias each. They still interact quite a bit. I can set bias for both V3+4 and V5+6 but if I have both in fixed bias the idle current for both increases quite a bit. Any guidance here? These current values include a switch to the grey 115VAC PT input tap – originally had used the black 125V tap.
B. Is my TUT bio editable? I did not know that info would be included with every post – can I delete the bio for new posts?
B. Is my TUT bio editable? I did not know that info would be included with every post – can I delete the bio for new posts?


