[Elecraft] When Transmitting on FT8 - KPA500 has issues - KD8ZYD

[Andy Durbin]

"In my case HDSDR sound output had spontaneously changed to TS-590 TX CODEC creating a feedback loop through
the PC.  Break the loop and all is normal.  

– Question, how do you break the loop?"

In my case I simply changed HDSDR sound output back to the Virtual Audio Cable it was intended to be assigned to.   If not using VAC the normal output selection would probably be PC speakers.

The symptoms of the feedback loop were oscillation of power output and TS-590 ALC at about 1 Hz.   The oscillation frequency depends on the delay between signal detection by my SDRPlay RSP, demodulation by HDSDR, and output on PC USB audio to the TS-590.   Seen it several times.  The first time was quite alarming.  Quick fix is to kill HDSDR.

I don't remember hearing any relay click at 1 Hz but I suppose it's possible the feedback loop could cause the KPA500 attenuator relay to activate.

73,
Andy, k3wyc

73,
Andy, k3wyc