In article ,
Fred McKenzie wrote:

If anyone is interested in the stability "fix", it involves using a
tantalum electrolytic capacitor (low ESR) in parallel with the 100 UF,
and a 330 Ohm 1 Watt resistor in parallel with the RF Choke.

That was Saturday. Today the "fix" is not working! The only difference
in my setup was the power supply.

I wanted to see if tuning an amplifier with less drive, might result in
more power when drive was increased. I tried 2 Watts, and then 0.3
Watts drive. In all cases, the instability shows up as garbage on the
nearby AM radio. The garbage comes and goes as tuning is adjusted.
When tuned with 0.3 Watts, output was the same when changing to the 2
Watt source. I think the amplifier is acting as an oscillator being
excited by the drive.

One difference between this "fix" and the one from the 70s, was before
the 100 UF capacitor had been replaced by three 22UF tantalum capacitors
in parallel. The current version only has one 22 UF tantalum capacitor
in parallel with the 100 UF. This may explain the motor-boating sound
of the interference.

My amplifiers oscillate but my oscillators don't!

Fred
K4DII