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Old 12-22-2021, 10:06 AM
rcarsey's Avatar
rcarsey rcarsey is offline
Join Date: Jul 2012
Location: North Brunswick, NJ
Posts: 406

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.
Rob Carsey, Winfield Park, NJ
RV-12iS (N713) / Completed 12/2020 / 350hrs and counting
APRS Track or ADSBExchange Track
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Old 12-23-2021, 10:38 PM
Lazerball Lazerball is offline
Join Date: Nov 2019
Location: Gastonia NC
Posts: 9

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.
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Old 12-24-2021, 10:32 AM
funflying funflying is offline
Join Date: Oct 2006
Location: arvada, co
Posts: 532

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.
Patrick Claar
Arvada, CO BJC
RV12, #401, Flying 2013, N612PC
RV6, 1996-2010 sold
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Old 12-24-2021, 11:01 AM
Piper J3's Avatar
Piper J3 Piper J3 is offline
Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 2,856

Try putting the Flightcom 403 Intercom into Pilot Isolate and see if static is any better.
Jim Stricker - EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC N86203
1130 hrs Flying 46 Piper J-3 Cub N6841H
Bought Flying RV-12 #120058 Oct 2015 with 48TT - Hobbs now 830

LSRM-A Certificate 2016 for RV-12 N633CM
Special Thanks... EJ Trucks - USN Crew Chief A-4 Skyhawk
MJ Stricker (Father - CFI) - USAAF 1st Lt. Captain B-17H
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Old 12-24-2021, 11:10 AM
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bjdecker bjdecker is offline
Join Date: Jun 2005
Location: Georgetown, TX
Posts: 1,431

Originally Posted by rkiefer2 View Post
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.).
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Brian Decker
RV-7 (Flying)
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Old 12-24-2021, 11:29 AM
carolsyracuse carolsyracuse is offline
Join Date: Oct 2006
Location: locust grove, ga
Posts: 182

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

Check out the Base Leg Aviation Youtube channel for RV maintenance tips.

Last edited by carolsyracuse : 12-24-2021 at 11:32 AM. Reason: Typo
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Old 12-24-2021, 11:36 AM
Carl Froehlich's Avatar
Carl Froehlich Carl Froehlich is offline
Join Date: Dec 2007
Location: Dogwood Airpark (VA42)
Posts: 4,028

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.

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.
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Old 12-24-2021, 01:53 PM
Richard Connell Richard Connell is offline
Join Date: Aug 2006
Location: Sydney Australia
Posts: 451

Originally Posted by bjdecker View Post
^^^ 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
RV7 VH-XRC Sold :-(
Sydney, AUS
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Old 12-27-2021, 06:20 PM
rkiefer2 rkiefer2 is offline
Join Date: May 2015
Location: Waukesha, WI
Posts: 110

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.

Roger Kiefer II
RV-12 SLSA - Flying/Instructing
Rv-8 Building
EAA Chapter 18 Member
Waukesha, WI (KUES)
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Old 12-28-2021, 07:33 AM
Mich48041 Mich48041 is offline
Join Date: Apr 2008
Location: Riley TWP MI
Posts: 3,457

Music input is not mentioned in the spreadsheet.
Neither is use of handheld radio.
Joe Gores
RV-12 Flying
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