Hi David,

That's an idea I haven't tried yet. I had tried a series C and R from gate to ground with no benefit but had not tried drain to gate.

I'm really not sure where it is oscillating. I am unable to determine that from what can only be described as utter chaos on the scope trace.

With some amount of luck I will have a better behaved PA on MF soon. LF is another story. I do have a plan but not a quick fix.

73,
Paul

Hi Paul.

Idea number ????      If your amplifier is oscillating above MF, then you may be able to tame it by using a series capacitor and resistor between drain and gate. This will apply frequency dependent negative feedback which should stop the oscillation. (Not ideal as it shouldn't oscillate anyway...but a likely fix)

Values are debatable, but 220R (1W) and 1000pF would be a place to start.

73

David

On Sun, Jan 7, 2018 at 12:19 PM, N1BUG <[email protected]> wrote:

Congratulations to 2E0ILY, G0LUJ, EB8ARZ/2, K3RWR, and WA3TTS/2 for the great trans-Atlantic work last night! Well done all.

After more than a year working toward it, I made my first two-way LF QSO with K3RWR. I was proud of myself for convincing the amplifier to put 16 watts into the antenna without any apparent funny business. Shortly after, while trying to set up on WSPR for the night, the amplifier took off and blew another FET. I then decided it was a good night for sleeping. :-)

73,
Paul N1BUG