[Elecraft] Rear Mike Jack Question

[N4ZR]

Recently, I began trying to use the rear microphone jack on my K3 with 
my Yamaha boom mike, instead of using a stand-alone USB sound card and 
feeding the signal to the LIN IN jack.  This worked fine for a couple of 
weeks, but today when I tried it, I got very loud white noise driving my 
radio and amp essentially to full scale. I have MIC SEL set to RPH BIAS, 
which has worked in the past. Any MIC gain setting over 7 drives the amp 
to full output.  When I pull the mike plug out of the jack, the problem 
goes away.

Have I inadvertently messed up another setting, or perhaps a failure in 
the mike?

-- 
73, Pete N4ZR
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