Tommy,
You are going to need a K2PAKIT from Elecraft. That kit includes a
matched set of PA transistors (replace both) as well as replacements for
Q11 and Q13 (also replace both). After you install Q11 and Q13, but
before you install Q7 and Q8, check the voltage on the base solder pads
for Q7 and Q8 during a TUNE - it should be no higher than 0.64 volts and
no lower than 0.61 volts. If it is not in range, find the cause and fix
that first so you do not zap the new PA transistors.
In addition to the PA transistors, check diodes D16 and D17 in the
KPA100 wattmeter and also diodes D1 and D2 in the KAT100 wattmeter and
replace them if there is any question about their health. You might
want to order 4 1N5711 diodes (Elecraft PN E560004) and arbitrarily
replace them.
What normally happens with a static surge on the antennas is that the
wattmeter diodes fail, and that causes the K2 to not sense the power
output - the MCU in the base K2, thinking there is no power output,
cranks up the drive to maximum possible, and that stresses the PA in the
base K2.
Good prevention is to add a DC path across all your feedlines (a high
value resistor - 5k to 50k will do or a 100 uHy choke of sufficient
current capacity) to bleed off static charge and arrange any antenna
switch to connect your K2 to a dummy load when not in use. You can get
static buildup on an antenna with no DC path across the feedline without
lightning - wind, rain, or snow can also cause a significant static
charge to build on the antenna.
73,
Don W3FPR
On 4/17/2013 8:58 PM, Tommy Mitchell wrote:
I sent this to Elecraft support, but I thought I'd post it here too to see
if the collective wisdom of the group might have anything to add.
Tonight during dinner I noticed my K2/100 (w/ KAT100) was showing no noise
on the S Meter. I unplugged the headphones and could hear no signals at
all, as if the antenna was disconnected. If I tried to tune, the ATU would
light up (sometimes) and it would run a tuning cycle, but I don't know if
it was finding a match. No noise at all on the bands.
I started taking the panels off and the next disconcerting bit was when
bits of plastic started falling out. Q11 and Q8 are both split in half
with most of the body of Q11 loose in the chassis and the base side of Q8
split from the collector & emitter.
I had left my radio on this afternoon while I was a few doors up the hill
working and we had a short thunderstorm. There were no close strikes (very
little lightning at all) but yeah, I should have disconnected things but
didn't realize I had left it in that state. A visual inspection doesn't
show anything else obviously wrong aside from some slight scorch mark where
Q11 went boom. No traces look blown and there are no signs that any of the
caps or resistors in that area are damaged.
Aside from Q11 & Q8, are there other likely candidates for replacement or
places to check? The ATU & PA100 pass a visual inspection. The storm is a
pretty strong correlation, but are there any other likely scenarios that
could cause this failure?
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