Good morning experts,
KXPA100 (serial #996) is back from the Elecraft shop. It spent about 3 weeks 
unconnected from its KX3. I sent it in because the amp was faulting and 
shutting down with NO detection of the fault using the KX3 or KXPA100 
utilities. The amp relay clicked and … just shut down in both the CW and SSB 
portions of the bands running ANY power (15watts or higher). My wire antennas 
are resonant.

The amp came back with a clean bill of health, my faults could not being 
replicated in the lab. The KXPA100 came back calibrated with factory test 
equipment (KX3) values. My 90 days of repair warranty is ticking …

The tech suggested that maybe the KX3 was overdriving the amp and suggested I 
do the Elecraft KXPA100 + KX3 Power Calibration. Beforehand, we eliminating 
cabling and power supply issues between the 2 units.

I have completed the CAL 75 calibration twice (2 times quickly, as he 
suggested) and with 110 watts selected on the KX3, the ATU in bypass mode and 
dummy load connected, I get the following power outputs and SWR readings from 
the KX3 display. 80 and 6 meters are well underperforming …. So far, I have had 
no faults, good news! Yes, the dummy load is swept as flat SWR via my RigExpert 
AA54.

Band    Watts           SWR     TX Gain 
1.840   100                     1.6             3.4
3.585   58                      1.1             4.6
7.120   87                      1.2             4.4
10.130  92                      1.3             3.7
14.200  97                      1.2             3.0
18.100  98                      1.2             2.4
21.200  93                      1.2             2.8
24.930  86                      1.4             2.4
28.400  93                      1.5             3.9
50.125  54                      1.1             5.0

For TX Gain (tX.X), see the KX3 manual, Appendix B, page 54. If I put the ATU 
back in with the dummy load and tune each band, the above values really don’t 
change at all, even on 80 and 6. The tech mentioned that he was not familiar 
with the TX Gain values and could not share any light on their goodness or 
validity. Can anyone speak to their reasonableness?

How do I get 80 and 6 meters to full power from the amp? Am I worrying 
needlessly? Sorry for the long post, help me, gurus!

Dave, K6WDE, KX3 #4599
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