Hi folks,
While phone contesting yesterday I found there is audio feedback from
headphones/external speakers through the microphone without the PTT being
pressed. Monitor level was initially set at about 15. I was using a Heil
BM-10ic headphone through the front panel with bias turned on. They have tiny
ear pads that could easily let an amount of noise slip past to the microphone.
The audio line out on my K3 back panel goes to a computer which has garden
variety speakers hooked to it's audio out.
On the radio I had the AF control turned most of the way up and was riding the
RF (IF) gain. NR was on with a setting of F1-2. I found that when the RF gain
was turned up something like half way or more (depending on signal level) the
audio level would creep up as though AGC was pumping. If the gain was further
increased the characteristic howl of feedback resulted. Remember all this was
occurring without PTT (no PTT light). I would have thought the microphone
would be dead without PTT.
I turned down the monitor to 8 and the feedback was not as much but was still
present. Finally I moved the volume control slider for the computer speakers
to the bottom and that eliminated the feedback.
I'm very surprised to find a microphone connected to the K3 is live and that
the audio is being feed to the audio outputs without the PTT being pressed
resulting in the described feedback. That is disappointing because it limits
the ways that I can use my radio. I'm wondering if this may be the source of
some noise comments here on the reflector. Does anyone else have any
experience with this or any constructive comments?
Have a good day and 73.
Jim, W0EM
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