10-11-2013, 08:31 AM
There should be a negative voltage on the grid cap of the 6K7. Close to zero when receiving no signal and several volts negative when tuned to a station. The negative voltage is produced by the AVC circuit, and the stronger the station the more negative it will be.
If you have a positive voltage on the grid cap, then you most likely have a bad 6K7. Considering that there was 260 V on the control grid of that tube, it is quite likely the tube has been damaged. Actually I am surprised that it still works at all !
If you have a positive voltage on the grid cap, then you most likely have a bad 6K7. Considering that there was 260 V on the control grid of that tube, it is quite likely the tube has been damaged. Actually I am surprised that it still works at all !