[Elecraft] KPA-1500: Strange Symptoms on FT8

[Andy Durbin]

I don't have the same equipment as you but I experienced a very similar problem that I initially thought was caused by a problem with my KPA500.    However, when I looked at the  output of my TS-590S with a scope and spectrum analyzer, I found that it was emitting out of band spurii at the end of each transmission.  The signal was clean before keying ended.  The problem was only seen on 10 m and 6 m.

My KAT500  reported a high SWR at end of transmission because the spike frequency was way off my SteppIR tuned frequency.  My TS-590S problem was caused a failed capacitor that changed the rise time of a pin diode bias signal and disrupted switching between TX and RX.

It may be a good idea to have a close look at your exciter output signal when TX ends.

73,
Andy, k3wyc