[Elecraft] KXPA100 70 to 80w out Max with KX3 drive at 15W???

[Kyle Krieg]

Hello all,

I used my KXPA100 this past weekend and noticed some lower than normal
output on both SSB and CW.  Sitting on the bench today I've noticed that
I'm only putting out around 70 to 80W max where I used to push close to
100w in previous outings.

I tested the drive of the KX3 to find that to be 15W max, so that is good
and spot on.  I've checked the power setting output on the KX3 to drive up
to 110W.  I've powered the KX3 from both the back of the amp and an
external power supply with the same results.  The KXPA100 power is from an
Astron power supply.  On key down it gives it about 11A's of power.  DC
doesn't drop below 13.5 on key down with the amp on while it's pushing the
72 W output. I've hooked up the KXPA100 utility and everything seems to be
working correctly with no faults found.  Short jumpers were used (less than
2ft) with quality cable from back of the KXPA100 to the Bird wattmeter then
to a HF dummy load.  SWR is flat on all bands.

Here is the power output per band on CW keydown.  The KX3 display is
showing 110W output.

160m : 80w
80m : 78w
60m : 73w
40m : 72w
30m : 80w
20m : 78w
17m : 92w
15m : 85w
12m : 80w
10m : 80w
6m : 76w

These numbers match between the windows utility and Bird wattmeter.

Thoughts?

Kyle