[Milsurplus] Test your repair skills

[Kenneth G. Gordon]

1) Hidden corrosion in and/or around the VFO tuning capacitor.

2) A bad silver mica shunting capacitor.

3) A bad NPO frequency-set tuning capacitor.

I had the indentical problem which you are having with a 
Heathkit VF-1. It would jump frequency periodically for no 
apparent reason. Tapping on the case, or twisting the chassis 
momentarily fixed it. It took me a year to track it down. It was a 
defective NPO silver mica or ceramic frequency-set tuning 
capacitor, one of those screwdriver adjusted 3 -30 pfd types,  
which was in parallel with the main-tuning cap.

After I replaced it, I had no further problems....and, to my mind, 
it was the last thing I would have suspected.

Ken Gordon W7EKB