Hi Everybody

I hope this isn't the wrong place to ask. if it is, please let me know
where I should post.

I have a Kenwood TS50 installed on a boat with a SGC autotuner. The
tuner is grounded to a dynaplate.

I also have a 2000watt inverter/charger built into the boat for ac power
creation from 12v batteries.

Something strange is going on and I jusr don't know where to start
trouble shooting.

When I transmit on frequencies like 14300MHZ usb, no problem.

If I transmit on 7628 LSB 100watts the FET's in my inverter blow up! As
soon as I key the mike I hear a loud pop and there goes another fet.

I've changed them twice now and since the inverter is bolted into an
awkward spot and weighs 70 pounds (it's all transformer), removing the
inverter and changing them ain't fun.

Tonight I went so far as to disconnect (as in unplug) the AC supply to
the inverter and switch it completely off. As in no LEDS lit, everything
off.

Yet as soon as I keyed the mic, POOF. The fets just blew apart.

Any thoughts as to what might be happening?

FWIW, the coax from radio to tuner runs within about 2 feet of the
inverter, the radio and tuner are powered from the batteries which power
the inverter. So the inverter and radio share Pos. and Neg.

I can only think of a few ways this might be happening:

1) Radiated signal from the coax leaking into the inverter.
2) Radiated signal passing into the inverter via the shared positive or
negative feeds.
3) Some weird ground loop issue.

I have no ideas as to how to diagnose this and trouble shoot it without
having to replace fets everytime. And that's a big job.

Any thoughts would be greatly appreciated.