[Elecraft] K3 KIO3 Problem with WSJT-X?

[N4ZR]

I am trying to diagnose a problem with my K3/KIO3 which surfaced during 
the ARRL VHF contest.  Previously, I had used this setup for hundreds of 
QSOs on HF.

I am using an external Startec USB soundcard.  The KIO3 IN jack is 
cabled to the speaker output of the soundcard.  The KIO3 OUT jack is 
cabled to the soundcard's LIN IN jack.  Now here's the problem.  When I 
transmit with all cables connected, and listen to the monitor on the 
headphones, I hear a tremendous blast of polyphonic audio so long as the 
KIO3 OUT line is connected to the soundcard.  If I pull that line from 
the sound card's LIN IN jack, then the FT8 audio in the monitor sounds 
completely normal.

It seems at least possible that the polyphonic audio bleat is being 
produced by feedback somehow occurring between LIN IN and LIN OUT on the 
KIO3.  Two possibilities - either the sound card has failed in this 
peculiar way, or there is some setting, either in my WIN 10 computer's 
sound settings or in the K3's settings, that is causing the coupling 
between LIN IN and LIN out.

Any suggestions gratefully received

-- 
73, Pete N4ZR
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