Static in KX-165A

I have two KX-165A nav/coms in my Cessna 320F and static can be heard
through the headsets from both of these radios. The static is not
noticeable while flying, but can be heard during taxi. It can also be
heard with both engines off and all circuit breakers pulled except the
radio circuit breakers. If I turn off the KMA-28 the static is much
quieter, but still present. I've tried different headsets and plugging
into a different intercom jack, but still the static is there. If I turn
the radios off, then the static is gone, so it is coming from the radios.
Is there an adjustment on the KX-165A's that could get rid of this static?

MikeM wrote:
Disconnect the power plug going into the back of the Turn Coordinator.
If the noise goes away, repost, and I will make some suggestions.

I pulled the circuit breaker for the TC and the noise is still there.

Chad Lemmen wrote:

I have two KX-165A nav/coms in my Cessna 320F and static can be heard
through the headsets from both of these radios. The static is not
noticeable while flying, but can be heard during taxi. It can also be
heard with both engines off and all circuit breakers pulled except the
radio circuit breakers. If I turn off the KMA-28 the static is much
quieter, but still present. I've tried different headsets and plugging
into a different intercom jack, but still the static is there. If I turn
the radios off, then the static is gone, so it is coming from the radios.
Is there an adjustment on the KX-165A's that could get rid of this static?

MikeM wrote:
Chad Lemmen wrote:

I pulled the circuit breaker for the TC and the noise is still there.

Is the squelch opening on either of the Com receivers? (In other words
does the noise follow the volume control of the respective Com
receiver?)

No

What happens if you disable the squelch in the two Com rxs if you pull
the volume control knob out? (If the squelch in either/both Coms is
open all the time, then pulling the knob out would make no difference)

I'll try this, but since the noise doesn't follow the volume control this
will probably open the squelch.

How about the Nav receivers? Does the hash loudness follow the Nav
volume control?

I'll have to check this, but unless I select nav1 or nav2 on the KMA-28
audio panel you can't listen to the navs so I wouldn't think the sound is
coming from the nav.

Did this ever work right, or is it a problem that just cropped up?

It's a new problem. The only thing that was done recently was the installation
of UMA light wedges. I also pulled the breaker on these though and the
problem didn't go away.

MikeM wrote:


Chad Lemmen wrote:

MikeM wrote:
Did this ever work right, or is it a problem that just cropped up?

It's a new problem. The only thing that was done recently was the installation
of UMA light wedges. I also pulled the breaker on these though and the
problem didn't go away.

Not familiar with UMA light wedges. Are they flourescent/electroluminescent, as
opposed to incandescent or LEDs?

They are electroluminescent, but since I get the noise even with the breaker
pulled for these lights I don't think they are what is causing it.
Maybe this sound has always been there, but I don't think so or at least
I just noticed it. I can also hear the retractable landing lights in
the headsets when the lights are either extending or retracting. This
is also something I never noticed before.