[Johnson] Ranger 1 Question/Problem

[Bruce J. Howes]

Hi guys (and gals),
 
My Ranger 1 seems to have developed a odd problem.
 
I was using it yesterday and all seemed fine until about 1/2 hour into
operation.
 
After about 1/2 hour I noted a "motor boating" sound in the receiver when
the transmitter was not keyed.
This would start out slow and then speed up until it covered up the stations
I was listening to on the receiver.
 
If I would key the transmitter then noise would stop briefly, then return in
30 seconds to to 1 minute.
This only happens when the VFO is selected, if I use a xtal setting, xtal in
the socket, no noise is noted.
I suspect that a component in the VFO is heating up and failing, perhaps a
capacitor allowing interstage leakage.
 
My question is if anyone has run across this before, and if so what
component failed?
Due to the tight conditions of the Johnson VFO, I would like to minimize the
surgery needed to diagnose and correct the fault.
Also the rather delayed nature of the problem makes it somewhat difficult to
repeat on the bench.
 
The key thing here is that it only seems to happen with the VFO on, not in
the xtal position, so it does seem to be a VFO fault.
Your ideas, thoughts and suggestions?
 
Thanks!
 
73 Bruce W1UJR