[Amps] instability issue - a bit more info

[N1BUG]

On a suggestion I checked the oscillation with a scope. It agrees 
with my frequency counter - oscillation around 400 - 450 kHz.

I failed to add in my first post... when this problem occurred 
during "normal" operation on 12M, the amp seemed stable during 
transmissions, apparently taking off at the moment of transition 
back to receive. That in mind, I am wondering if I should 
investigate the timing of relay and bias switching. This behavior 
may suggest the vacuum relay contact on the amp is opening before 
cutoff bias is applied.

The other really ugly thing I failed to mention is that this 
oscillation would then continue until I toggled the amp 
operate/standby switch to standby. I suspect this LF RF is getting 
into places where there should not be RF.

73,
Paul


-- 
Paul Kelley, N1BUG
RFI Committee chair,
Piscataquis Amateur Radio Club
http://www.k1pq.org