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?


You probably has a resonance in the DC-cable.

Try to install ferrite rings in the cables going in and out of the
inverter,( in both ends ) plus on the coax from the rig - in both ends.
Put one more than one on the DC-cables to be on the safe side.

Good luck

Rag LA5HE