Constant squeal/RX indication on GNS 530W

[Fearless Tower]

Experienced an intestine anomaly on the last two flights in the Twin Beech.

After startup, once I turn the avionics switch on, I get a constant squealing tone from Comm 1 (GNS 530W) and associates RX indication on the display. Affects all frequencies. Changing headsets didn’t change it either.

No issue with Comm 2 (KX155), so I used that and departed. In the air, the problem was still there. But about 30 minutes into the flight, in cruise, the RX indication went away and so did the squeal. So I went back to comm 1 and was able to communicate with ATC just fine all the way to my destination.

Then upon startup today, same thing started all over again. Again, about 30 minutes into the flight, the problem went away, and I could use the radio again.

Anyone ever run into this? Any thoughts on what is causing the issue?

We are going to try and find another 530 to swap and see of the problem follows the box or stays with the plane. Anything else we should check?

 

[bnt83]

Does it start/stop when switching generators on/off?

 

[Fearless Tower]

Does it start/stop when switching generators on/off?

No. I figured it out today. At first I couldn’t duplicate it. Then I realized what was different: I had bought a portable fan for my wife to use on the ground in the summer that plugs into the cabin cigarette lighter outlet.

With the fan plugged in and running it produced the squeal which stopped as soon as you unplug it.

That’s why it stopped in flight once I leveled off in cruise. Cabin was cool enough that she would turn it off.

Guess I’m stuck with comm 2 on the ground for the summer family flights....

 

[hindsight2020]

Battery powered fan maybe? It's only occasional/part-time use.

 

[frfly172]

Makes sense,when I plug my I pad and stratus into the cigarette lighter. Al ost went to an avionics shop,before I found the problem.

 

[flyer770]

Cheap cigarette lighter USB chargers can do that.

 

[Fearless Tower]

What’s is interesting is that it only affected the Garmin and not the KX155

 

[Ravioli]

Tell me about the power source to your accessory. Is it a standard cig adapter?

I ask because we once bought a cheapo USB charger and guess what happened. Then we bought the OUTRAGEOUSLY priced USB charger and it worked without interference.

In the interim there was testing, the shop said it was fine for $x. Another member flew who it, no issues. A third member flew it, no issues. The guy plugging in a bunch of iJunk and the toaster flies it, WHAM! Back to the shop.

As Judge Milian would tell us, "lo barato se vuelve costoso"

 

[Fearless Tower]

Tell me about the power source to your accessory. Is it a standard cig adapter?

My Beech has a cockpit plug on the center pedestal and two outlets in the passenger cabin. Both built into the foldout table/desk. Judging by the fact that there is still a 'Co-pilot Call' button mounted next to the outlet, I suspect the cabin outlets are original 1960 and likely had actual lighters with them when delivered. The airplane itself is a 28V system, but the cockpit outlets are 12V. The fan was purchased new from an auto parts store. I haven't tried using it on the cockpit outlet which is probably newer than the cabin ones.