Yesterday afternoon an unexpected thunderstorm developed before I got a
chance to disconnect the antenna. A few cloud to ground strikes hit
probably between a half and one mile way. Also what seems to have been
a cloud to cloud strike occurred overhead while the transmitter was
still connected. After the storm passed I powered back up. Initially
all looked well but after watching the amp for a while I noticed small
erratic changed in the FET current and output power. Also the power
would creep up a bit during key down. Normally while operating at 400
watts the power would drop off a few watts during key down. I let it
run overnight and this morning found the power to be down a bit but
stable. About mid day I was just outside the shack and heard what sound
like a metal pail falling to the floor and rolling around. Upon opening
the shack door I immediately noticed the smell of burnt electronic
components and no output from the amp. Upon removing the amp cover I
saw FET guts scattered over the board and a black area on the PC board
near the FETs. The amp has been so stable and reliable I can't help but
suspect the FETs were damaged during the storm. So I'll be off the air
for a while. On a positive note, since it's as warm outside as in the
house I'll waste no energy airing the odor out before the wife returns home.
Dex, W4DEX / WD2XKO
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