[Elecraft] K3 Single Band SWR problem

[Craig D. Smith]

My first real problem (or operator error?) with K3 SN 608 just occurred.  I
got on 20 CW with my usual antenna (a resonant dipole) and the K3 is showing
a 2:1 SWR and folding back power.  I bypass the tuner with this antenna
since its SWR is in the 1.2 to 1.3 range.  My external SWR meter shows the
usual 1.3.  If I engage the K3 tuner it will tune to a 1:1 indication on the
K3 meter and register the requested output power, but the actual output
power measured externally is in the range of 70 to 80 W for 100W on the K3
meter.

Next I tried a known good dummy load and the K3 acts the same with it -
indicates a 2 to 1 SWR.  Interestingly, it works fine with the dummy load on
all the other bands (shows 1.0 to 1 SWR) except 20.  It has worked fine
before on 20 with this same antenna and as far as I know nothing has
changed.  I'm running firmware version 1.78. 

Will welcome any ideas or suggestions

          Thanks
                       ... Craig  AC0DS