[Elecraft] Very High SWR on all bands; K3 #6957

[Peter Lock]

Good day

I was using my K3 on 80m sideband into a dipole with a good SWR reading 
(1.5:1), in a contest.  I inadvertently yanked the headset cable from 
the rear connectors; my headset has a TRRS plug and was connected via a 
commercial y-adapter to 2x TRS.  I thought I had probably broken one of 
the cables in the y-adapter internally, and as it was cold and I was 
operating portable, I packed up without doing a lot of investigation.

I acquired a new y-adapter which I tested on another rig.  When I went 
back to the K3, I found very high (49 to 99:1) SWR readings on all bands 
into a good dummy load.  The ATU would attempt to make a match but the 
best was 6:1.  I was using 20W tuning power but the results were the 
same using 5W.  The same results were obtained using ANT1 and ANT2 (for 
the avoidance of doubt, with the dummy load on the appropriate output 
socket)

Having found an old thread in the archives 
(https://elecraft.mailman.qth.narkive.com/IHFmlCeA/k3-output-stage-high-swr-fault-finding) 
that reported some possible heat injury to T4 in the SWR bridge with 
similar SWR readings on all bands, I have dismantled the radio and 
inspected T3 and T4 which both look good.  The surrounding area on both 
sides of the RF board looks undamaged. The KAT3 ATU board also looks 
undamaged.

I suspect the mechanical insult to the rear panel is probably unrelated 
to the issue of the high SWR readings, but it is part of the history of 
events.

I would be most grateful for any advice on further troubleshooting.

Peter

M0RYB