K2/100 Low output on 20/17 only

[Ralph McClintock-2]

Hello all,
 I have discovered that the 20 and 17 meter ouput power of my K2/100 is running around 65-70 watts maximum. The other bands all put out the normal 100 watts. (85-90 watts on 10 meters.) When you try to go up to the 70-100 watt level on 20 or 17 meters the K2 flashes a Hi-Currect warning. The rig keeps going but only puts out 65 watts. I checked all the caps in the 20/17 output filter and all are printed as the correct values. The 2 coils have the correct # of turns and are in the correct positions. The 100 watt amp has all the updates. I am suspecting that 1 or more of the capacitors is out of tolerance in the 20/17 filter assembly--- but then !
 Any ideas would be appreciated.
Ralph  W1ZK
K2/100 # 3827
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[Vic K2VCO]

Ralph McClintock wrote:
> Hello all, I have discovered that the 20 and 17 meter ouput power of
> my K2/100 is running around 65-70 watts maximum. The other bands all
> put out the normal 100 watts. (85-90 watts on 10 meters.) When you
> try to go up to the 70-100 watt level on 20 or 17 meters the K2
> flashes a Hi-Currect warning.

First check the current draw with the K2 set to 10 watts.  If it puts
out 10 watts with reasonable current (less than 3A), the problem is in
the amplifier.  In that case, there may be a problem with C80/81 and/or
R190/20.  Elecraft has supplied replacements for these components --
some resistors were overly inductive, and some capacitors low in value.

If you can't get 10 watts with reasonable current from the driver, then
check the tuning of the bandpass filters on 20/17 meters.  My early K2
had to have some extra capacitance added to the trimmers to hit resonance.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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