[Elecraft] K3 output stage high SWR - fault-finding?

[g7vjr]

Hi guys,

I have a problem with my K3 reading 5.0:1 or more SWR on tune into a 50 ohm
load. I was alerted to this problem when I could not get the same SWR my
analyser was showing for a new antenna, and quickly  discovered the K3 had
developed a fault on all bands.

The K3 shows a high SWR into a pure 50 ohm load or resonant antenna on both
Ant 1 or Ant 2. I find that if I use an external SWR meter and connect the
K3 to a dummy load through that, the SWR shows high on both the K3 and the
SWR meter. I have checked the dummy load and patch lead. So, at a guess, the
SWR reading on the K3 is correct and there is something wrong in the output
stage of my K3. 

I have the ATU module and find this is able to tune back to 1.0:1, but I'm
pretty sure that's treating the symptom rather than the cause!

Any suggestions or advice on fault-finding this would be most welcome;
sadly, I'm off the air!

Many thanks,
Michael G7VJR

K3/100 no. 1904
KXV3
KAT3
KRX3
KDVR3

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