[Elecraft] Power Readout Discrepency

[Parker Buckley]

My K2, #2636 has always had a large discrepancy in the
displayed power vs what I see on other, external wattmeters,
including units from Oak Hills and Diamond.  I know these
are not lab quality devices, but I still think things should
agree a little better.  I talked to Eric about this
yesterday at Dayton.  I get the idea that non-linearities in
the rf detector D9 could be a factor.  Has anyone had any
experience with this?  I'm thinking of replacing D9 just to
see if that's the problem.  Below are my K2-indicated power
levels for 10 watts out, measured through a Diamond
wattmeter connected to a commercial dummy load.  Bands
progress from 160 through 10 meters, respectively.  I see
similar non-linearity at lower powers through the WM-2
wattmeter.

8.2, 8.5, 8.8, 8.4, 6.2, 6.8, 8.6, 11.0, 11.0

I would appreciate any comments on this.  I've confirmed
that I have the correct diode at D9 and solder joints are
good.

Parker WD8JOL