Static on radio DESPERATE TO SOLVE

[rcarsey]

I'll echo what everyone else said. Any DC-to-DC power supply (or a switching power supply) is very noisy. I'm not sure if the legacy RV-12 came with extra USB power ports mounted somewhere.

The fact that the intercom is OK, but the radio-receive is garbage, makes me quickly exclude the headset/wires/intercom. Based on what you said, sounds like the antenna and coax can be excluded too. The only thing that's really left are the speaker and mic wires between the radio and intercom, and the power to the radio, especially the -12v (ground) to the radio.

[Lazerball]

I have the same problem with static noise on the radio. Installed a new antenna and replaced the co-ax cable with RG-400. Noise is still there, however if I hold the antenna while receiving the noise goes away. By the way the noise is only on certain frequencies, not all of them.

[funflying]

Last year I had issues with my SL40 and sent it in to Garmin for service. Before using the repaired (circuit board replaced) unit the avionics shop wanted an SWR check done on the antenna to check the connection integrity between the radio and antenna. A young man, not very experienced with the equipment, put the SWR meter on the antenna and on the antenna cable under the fuselage. He checked through the frequency range and was looking at the meter for low readings. He had someone on the phone with him from their shop who was better versed with what they should be seeing and felt everything looked good to continue using. It’s been working well for almost a year now, and I don’t believe there was any issues with the antenna or cable when the radio developed the over modulation problem.

My point (finally) is when he was checking the different frequencies the meter would show different readings, and he said the radio did better at different frequency ranges than others. All were not equal and this was normal.

[Piper J3]

Try putting the Flightcom 403 Intercom into Pilot Isolate and see if static is any better.

[bjdecker]

Originally Posted by rkiefer2

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.

^^^ This ^^^ Got me thinking;

Check the condition of the shoulder washers & isolation washers installed under the mic & phone jacks. If you don't know what they look like - here's a pic.

I had a similar "static" issue in my previous RV-7 that I built -- the shoulder washer had cracked and created a ground loop of sorts (moisture permeated the crack perhaps.).

[carolsyracuse]

So is it static or breaking squelch?
There were some s/w updates that addressed the squelch issues.

Vic

[Carl Froehlich]

I strongly recommend everyone put an antenna analyzer on their antennas at the end of the feedline going to the radios. Do this during the build and anytime you change something or have a radio problem. This tells truth and is a much preferred shortcut to the typical “change stuff out at random” approach.

Side note: Using an analyzer is how you make a wingtip VOR/ILS antenna work to its full potential.

Here is a nice one that can be a shared tool for Airparks, EAA chapters and such. Find an Amateur Radio Operator that knows something other than digital comms to show you how to use it.
https://www.dxengineering.com/parts/mfj-259d

With the little information provided, I’d guess the antenna is not the issue but I’d start there anyway as it is dirt dimple to check with an analyzer. Instead this maybe standard RFI coming from someplace yet to be determined.

A simple tool to go search for RFI is a hand held radio with a little rubber duck antenna. Sit in the plane (with the plane outside the hangar) and listen to ADIS or such. Then change to a frequency not in use. Now with all breakers open shut your master switch(s) and listen to the change in noise on the handheld. Move the handheld around looking for a increase in noise (as in your are moving it around to see if anything changes as the handheld gets closer to stuff in the panel). Now bring the non-panel stuff up one breaker at a time and repeat. After that bring up the panel one breaker at a time and repeat. Hopefully you will find the culprit (unless it is the Garmin radio itself but even is so it might show up on your handheld).

Note - do not have any external power connected to the plane for these checks. If needed charge the battery(s) after you are done.

Let us know what you find out.
Carl

[Richard Connell]

Originally Posted by bjdecker

^^^ This ^^^ Got me thinking;

Check the condition of the shoulder washers & isolation washers installed under the mic & phone jacks. If you don't know what they look like - here's a pic.

I had a similar "static" issue in my previous RV-7 that I built -- the shoulder washer had cracked and created a ground loop of sorts (moisture permeated the crack perhaps.).

Had this exact problem on my 7 as well. Was very frustrating.
The jack nuts had just come loose

[rkiefer2]

Thank you everyone for your input. I've read through all the replies and recommendations.

This saga continues for me. I built the below matrix of actions taken and the results in hopes it helps as a guide to solving the problem and/or helps someone in the future with the same or similar issue.

I will keep the below Google Sheet updated with the tried and current recommendations.

PLEASE COMMENT ON ANY ADDITONAL RECOMMENDATIONS....IM TROLLING THIS ON FORUM DAILY FOR SUPPORT.

https://docs.google.com/spreadsheets...it?usp=sharing

[Mich48041]

Music input is not mentioned in the spreadsheet.
Neither is use of handheld radio.