[Elecraft] Background Noise with Mike Plugged in to Rear Mike Jack

[Pete Smith N4ZR]

I don't normally operate phone, but wanted to contribute a few QSOs to 
my club in SS SSB.  So I recorded messages on my external USB sound 
card, using Audacity.  They sounded fine, both on a speaker and on my 
K3's monitor.  So then I plugged my Yamaha CM-500 condenser mike headset 
into the rear microphone jack, with MIC SEL = rP.L bIAS.  That worked 
OK, but there was a very high level of white noise, audible both with 
live voice and while playing recorded contest messages.  I was reading 
700 watts out without talking.

Experimenting, I discovered that the source of the noise was definitely 
the mike on the rear microphone jack.  I also didn't like the fact that 
in this setup the mike was live while recorded messages were playing.

How can I rig things so that the mike doesn't contribute this high level 
of background noise, and how can I manage things so that the microphone 
is muted when the recorded messages are playing through the line in jack.

-- 
73, Pete N4ZR
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