[TenTec] Omni D issue

[Douglas via TenTec]

One of my Omni D's (series C) has starting having a problem...

It shows up first on CW - the final current will suddenly jump up and trip out the supply.
It seems to do this only over a very narrow temperature range. Cold it's fine, with the final amp assembly warm, it's fine.
As I back off of drive, the behavior returns to normal at around 60 watts. As I push drive toward 100 watts current will jump, especially on high speed CW "dits" from around 16 amps to over 20 and the supply will trip out. As the process is repeated a few times, perhaps due to the the final amp assembly warming up, and then all is fine, making it hard to troubleshoot.

Using a second Omni D with the same power supply, antenna tuner and antenna and all is fine.

Something in the final amp breaking down at a certain temperature range??

Any thoughts?

73,

Doug/WA1TUT