01-05-2022, 11:36 AM
I connected my oscilloscope to the grid of the magnetic tuning amp and was able to easily peak the 77 trimmer for maximum signal (this with signal generator with a medium signal at 1000kc). I then removed the 6H6 discriminator and installed a dummy tube base with leads on the plate pins, to which I then connected the oscilloscope. I was able to easily trim 85A and 85B for maximum signal, also found that 77 could be trimmed better (it had peaked at a different setting due to the scope lead capacitance).
Magnetic tuning still doesn’t seem to function. I am suspecting that the 6H6 May be bad, although it shows good on my emissions tester. When first tested, heaters did not work; but when I measured heater resistance at 7ohms, I reinstalled it in the tester and it checked good. An original Philco tube....
Next step is to remove chassis and measure voltage across the AFC kill switch.
Magnetic tuning still doesn’t seem to function. I am suspecting that the 6H6 May be bad, although it shows good on my emissions tester. When first tested, heaters did not work; but when I measured heater resistance at 7ohms, I reinstalled it in the tester and it checked good. An original Philco tube....
Next step is to remove chassis and measure voltage across the AFC kill switch.
