[Elecraft] K3 high SWR at end of transmission

[w2yf]

I've run into an interesting issue:

I get a high SWR report from the SW; command on a K3 -- only at the end of
a transmission cycle.

Things I have tested:

- Occurs on ANT1 or ANT2.
- Occurs when LPA is engaged (5w) or PA is engaged (25w).
- Always occurs, if transmission is 15 seconds long, or 3 seconds long.
- Occurs on antenna matched at 1.3:1 and a perfectly matched dummy load.
- Occurs with ATU engaged and without ATU engaged.
- Is only at the end of transmission as the transmission envelope is
falling off
- I have calibrated the transmitter, identical results as above.
- All coax has been swapped -- identical results.
- SWR throughout entire transmission is 1.1:1, but then when PTT closes it
reports 20.9:1
- Bar graph on K3 shows no SWR variance at all, from the bar graph
perspective it is as if nothing is happening with SWR... this only appears
when polled via the "SW;" command (via Hamlib).

Is this a known bug in the K3 firmware? Is it symbolic of hardware that is
on the edge of failure?

The fact that it occurs only at the end of transmission and never during
(regardless of length) is odd.

Tom, W2YF