NEED HELP! No grid current on my Johnson Valiant I transmitter!

[KF4IZE]

Hello All,

I was in the middle of the QSO when I lost grid current on my Johnson Valiant I xmter. I have good readings in the OSC and BUFFER positions, but zero current in GRID or PLATE, NO RF output. Any help would be greatly appreciated! Thanks much in advance.

73,
Will KF4IZE

[KB2WIG]

 Can you hear the osc onyour receiver?
Do you have a scope?

Yoy could try signal tracing with the scpd ho see where the signal goes away
. Keeping your hand nx in your pocket,check the stage voltages.


Klc

[N1BCG]

Start with the easy tests:

1) Switch bands - there are a lot of contacts on the rotary band switch.

2) Rotate the AM/CW/SSB Mode switch - the RF path goes through this switch.

3) Check the voltages on the Drive pot - one lead is connected to the +300 volt supply, the wiper supplies voltage to the screen grid of the 5763 driver tube, and the remaining contact is grounded. This is a wire wound pot and they are known to burn/wear out.

Clark

[KF4IZE]

Thanks to all whom responded to my plea for help. As it turned out, it was the 6BY5 bias rectifier tube that gave up the ghost. So, in the meantime, I have relegated back to the solid-state bias mod until I can obtain another bias tube. I discovered this, of course, after much testing of various circuits. It never fails; at the end of the day, the culprit almost always turns out to be something minute or trivial. I guess I need to brush up on my troubleshooting techniques.

73,
Will KF4IZE

[KL7OF]

It never fails; at the end of the day, the culprit almost always turns out to be something minute or trivial. I guess I need to brush up on my troubleshooting techniques.

73,
Will KF4IZE

You just did....