[Elecraft] K3: High VSWR indication on 6m only

[Stephen Prior]

Whilst calling CQ on 6m tonight (100W into about 1.3:1 VSWR), all of a
sudden I got a high SWR indication (4.9:1).  Forcing a retune of the auto
ATU did not improve it.  I checked the VSWR with my Kuranishi BR210 analyser
and it reported about 1.5:1 VSWR.

I then connected the K3 to a Bird dummy load.  The K3 reports the VSWR on 6m
into the dummy load as 3.6:1.  On all other bands the K3 reports 1.0:1.  My
Kuranishi meter confirms the VSWR of the Bird load to be no more than 1.2:1
up above 150MHz.

It is as if the K3's reflected power measurement on 6m only has become
faulty. Has this been seen before?

Stephen G4SJP