[Elecraft] KPA500 Issue ?

[Paul Ecker]

 Running K4D, KPA500, KAT500 and Win11 PC
I have three antennas connected to the KAT500.
The KPA500 works as expected with antenna 1 & 3 but when antenna 2 is
selected , no power amplification is achieved
Antenna 2 has low SWR on all bands.
I did the testing with the same settings on the K4.
So are there some settings in either the KPA or the KAT setup that I have
missed that may be causing this problem.
Any help would be appreciated
73 Paul w2eck