Just finishing up building my KPA100 and performing
transmiter testing and noticed I was only able to get
a reading of 93w on 12m (one the K2 display), while I
could get 100w+ on all other bands. Current drain on
12m was similar to all other bands (less than 18A by
measuring voltage drop across R7.) Forward power was
calibrated at 20w level using the RF probe provided in
the base K2 kit across 50 ohm non-inductive dummy
load. Forward power indication on all bands on my MFJ
tuner's meter was 10-25w higher than the indication on
the K2 itself, but I don't really trust its accuracy.
I wouldn't guess a low pass filter issue as it is
shared between 15/12/10m, and output was fine on 15m
and 10m, but I haven't swept the LPF with an SWR
analyzer or anything, since I don't own one. Could
this low power be caused by incorrect bias current
setting? I found this setting to be quite tricky, and
I'm not for sure I got it right. I was using a
digital meter to do the measurement, and I found the
display update delay to make the setting difficult. I
was using a Fluke 111, and the display blipped through
approximately .5A on its way to approximately .8A,
which was my target setting. Any insight would be
appreciated.
-Ben K1NT
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