Static on radio DESPERATE TO SOLVE

rkiefer2 · #1 12-21-2021, 09:51 PM

Hello,

I’ve got a factory built 2013 RV12 ULS with Dynon classic view, Garmin SL40 radio, Flight com 403 intercom, auto pilot, and ADSB.

PROBLEM: When radio is receiving I it get static with the radio call.

Intercom works great, my transmissions to others are clear. NO STATIC OTHER THEN WHEN I RECEIVE. I’ve spent about 10 hours checking wires, connections, turning off lights, turning off Dynon, off ELT, replaced intercom, had Garmin radio bench tested, reseated/sealed antenna, even took it to an avionics shop and spent $2000 for them to replace the coaxial cables with shielded ones. Also I did find initially a loose ground on the connector behind the tray, tightened, ALL NO HELP.

Everything worked good for about 4 hours and then the static returned with a radio call randomly and looks like it is here to stay.

I’m hitting a wall on this one and desperate for some help with a solution. Any ideas on what else I should do specifically or things to try?

greghughespdx · #2 12-21-2021, 10:25 PM

You don't have a third-party/cheap USB power plug installed, do you? Asking just because those can cause a lot of noise sometimes. Is the static also present when the airplane is not running?

rkiefer2 · #3 12-21-2021, 10:47 PM

Nothing installed in the USB

Piper J3 · #4 12-21-2021, 11:29 PM

You might check antenna connection on back of radio tray for SL40. The 90 degree connector is fastened to the tray with two screws that can come loose – happened to me. To do thorough inspection, you need to remove instrument bay top sheet metal.
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Mike S · #5 12-22-2021, 12:18 AM

Quote:

Originally Posted by rkiefer2

Nothing installed in the USB

I believe Greg was referring to the outlet itself, not something plugged into an outlet.

Avanza · #6 12-22-2021, 04:25 AM

If distance between COM / GPS-antenna is less than 3 ft, I would unplug
the GPS-antenna from the Dynon Classic just to check.
The GPS-antenna is DC powered.
A notch filter on the SL40 may help.

Good luck

mike newall · #7 12-22-2021, 04:27 AM

Also, check the music input jack socket. That was the cause of static on our 12.

Agree with Greg - USB sockets can spew RF out unless you get a specific suppressed one. Don't need to be expensive, plenty of references on the forum.

GatorsR1 · #8 12-22-2021, 08:21 AM

My radio (GTR200b) noise issue seemed to be only on transmit.
Pulled the Dynon screen to got behind the panel & check connections, took radio out for exam, pulled wings out to install new headset jack isolators.
After days of doing all that, I happened to crawl under the plane to visually checkout the bottom surfaces and noticed the com antenna didn't appear tight to fuselage.
Sure enough, the phillips head screws turned rather freely.
Opened inspection port, so as to hold nuts, and tightened the screws,
Voila ... perfect comm again.
Was focused on the front end had neglected to think about the "whole" system (ground plane interuptus)

Mich48041 · #9 12-22-2021, 09:04 AM

Try using a handheld radio. If that receives static too, then you will know that
the static is coming through the air and not through wires.

N804RV · #10 12-22-2021, 09:28 AM

Not just cheap USB sockets.

Those USB "power banks" are noisy too. Lots of folks who were running the homemade Stratux ADS-B receivers were powering them with really noisy "power banks". And, having problems with those power banks actually breaking squelch on their com radios.

If you have to have one in your airplane, buy the ones from Sporty's that are made to be low-noise.