Envelope-to: dave@picks.force9.co.uk
Delivery-date: Thu, 12 Jan 2006 18:10:48 +0000
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Date: Thu, 12 Jan 2006 18:09:42 +0000
From: Dexter McIntyre W4DEX <dmcintyre@att.net>
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To: RSGB LF <rsgb_lf_group@blacksheep.org>, LowFer LWCA <lowfer@lwca.org>
Subject: LF: XKO off due to amp failure
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Reply-To: rsgb_lf_group@blacksheep.org

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