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.