10-11-2016, 11:13 PM
Agree with Trevor, I bet the last stage V6 (or just possibly V5) is acting as a limiter.
I take it that the obvious checks have been done - screen-grid voltage OK? Cathode bias resistance not gone high?
What happens if you pull V4 and feed a medium-level steady 45MHz signal in at its anode valveholder pin (via a DC blocking cap!), can you get 20V out of the detector and is it linear as you vary the input level?
Hours of fun!
I take it that the obvious checks have been done - screen-grid voltage OK? Cathode bias resistance not gone high?
What happens if you pull V4 and feed a medium-level steady 45MHz signal in at its anode valveholder pin (via a DC blocking cap!), can you get 20V out of the detector and is it linear as you vary the input level?
Hours of fun!
