Bryan,
The potential issue with T1 is getting the phase for the secondary wrong.? If that is the case, instead of push-pull, the two IRF510s will both conduct simultaneously and cancel each other.? That is when the oscilloscope is needed; to verify the phase.? If this is the case, you should see RF on both gates and almost none on T2.
Since all of the other checks were OK, this is the last thing that I can think of that could be causing the issue.? At least one of the IRF510s is conducting as the bias adjustment confirms.? Even with the other one failed open, you should see some RF out.
I checked my 40meter 50watt PA with my RF probe and did see first a slight drop (there is a 6DB attenuator on the input), the same voltage on the gates, then a significant increase on the drains of the IRF510s, and finally another increase in voltage on the output of T3.
At Input BNC? ? ?R3/R4 Junction? ? ?IRF510 Gates? ? ? ?T3 Primary? ? ?T3 Secondary? ? ?Output BNC
? ? 10.4? ? ? ? ? ? ? ? ? ? ?6.43? ? ? ? ? ? ? ? ? ? ? ?9.7? ? ? ? ? ? ? ? ? ? ? ? 20? ? ? ? ? ? ? ? ? ? 43? ? ? ? ? ? ? ? ? ? ? ?37.4
I measured 39watts out.? Verifies that the RF probe is working OK.? NOT lab grade.
The above measurements are made with 13.8 volts to both the QCX+ and the 50watt Amp.
I hope the above helps.
73
Evan
AC9TU
