[Elecraft] K2/100 funny reading

[Vic Rosenthal]

I just noticed a strange phenomenon with my K2/100.  I adjust the power control
for 100 watts and transmit into a dummy load.  The external wattmeter shows 96w,
more or less correct.  Then I transmit into my real antenna and I see only 65w. 
The SWR on the antenna is only 1.37:1, so the K2 is not reducing the power
because of that.

The above happens on 15 meters.  On 20 meters, I get 100 watts on both the dummy
and the real antenna (whose SWR is much better, 1.05:1).

Any ideas?

Vic K2VCO