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RFI obliterating radio reception

moonpup

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In my 2018 JL, I have a Yaesu FTM-300 installed and when trying to receive transmissions when the vehicle is running this video shows what happens. I have tried the following things and nothing has resolved my issue, nor have I found the source of this interference.

  • tried different radios, antennas, coax and connectors
  • moved antenna from back of Jeep to front and both sides
  • moved body of radio to different locations
  • tried ferrite beads
  • tried an inline power line filter
  • extensive grounding options
  • used an HT on battery power to rule out the installed radio and antenna in the Jeep (the HT suffers the same fate)
  • not a multipath problem
My ham radio buddy, who is extremely knowledgeable and has all the good test equipment, put his oscilloscope on the battery and the power is completely clean. So it's not that. We ran an RF analyzer and short of some noise in the 260 mhz range, there doesn't appear to be any spikes in the 2m and 70cm ranges. This is the first time in my life where a vehicle has posed this type of problem. At this point we are completely stumped.

Has anyone with one of these newer wranglers experienced such a noise problem? Any idea what could be generating this RFI? Watch the video and see how awful it is... I have also recently installed a GMRS mobile in the Jeep and it suffers from the same problem.

Here's my reddit video post - click the title in photo

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jeepoch

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@moonpup,

Simple question, I didn't see it in your list of filtering attempts.

Are your radio(s) connected strait to the battery? Or are they wired into some switched circuit inside the cabin?

I had a similar problem on a Dodge van a few years back. It turned out that it was ignition feedback into the power feed that I had tapped into. I did this for pure convenience. My solution was to replace the spark plugs with a noise suppression variant. Worked well enough that I didn't bother to rewire anything.

For my 2019 JL Sport 3.6L, I found and used the direct (unswitched) battery power feed behind the Uconnect radio. I have both my HAM and CB radios connected there with near zero (imperceptible) interference.

Hope this helps in some small way.
Jay
KF0EUD
73
 

bjm00se

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After reading everything you tried, plus the linked reddit thread:
1. as above, dedicated red power wire and black ground wire from the unit to the terminals on the battery
2. "Ground plane" on antenna is NOT the same thing as 12VDC electrical ground. The antenna should NOT be grounded to the battery, but rather to the metal body of the vehicle. The fenders and roof are both plastic, and do not provide good ground plane. (In fact, it's notoriously difficult to get a good ground plane on Wranglers) I'd try running a short flat copper braid (not wire) to the nearest paint-scraped body ground location I could find.

Good luck.
KJ6LMK.
 
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moonpup

moonpup

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Yes, the radio power cord is direct to both battery terminals. I understand the importance of grounding, but since this same situation occurs when testing with an HT using a rubber duck antenna, that's not my issue here. It's trying to find and resolve what's generating this darn RFI...
 

bjm00se

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Yes, the radio power cord is direct to both battery terminals. I understand the importance of grounding, but since this same situation occurs when testing with an HT using a rubber duck antenna, that's not my issue here. It's trying to find and resolve what's generating this darn RFI...
I had a new thought. Do you by any chance have LED headlights? And if so are the LED daytime running lights on?

I have horrible FM interference from an LED light bar.

Then, grasping at straws, noise suppression spark plugs and spark plug wires.

After that, voodoo dancing in the moonlight with tattoos.
 

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jeepoch

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Yes, the radio power cord is direct to both battery terminals. I understand the importance of grounding, but since this same situation occurs when testing with an HT using a rubber duck antenna, that's not my issue here. It's trying to find and resolve what's generating this darn RFI...
Does the interference change frequency with engine RPM?

If so, have you considered noise suppression spark plugs and wires. These have ferrite chokes, shielding and resistive elements built in. Standard factory braided ignition cables can act as an antenna and are notorious RFI emitters.

If the interference remains constant at a fixed frequency, then suspect some other electronic component within your JL. Do you have the safety package with adaptive cruise control? Do you have a premium radio with a power amplifier? LED lighting?What is unique with your Jeep?

As Bullwinkle mentions above the JL's ground plane is it's chassis, not the body. There is very little metal surfaces in which to acquire a proper ground plane. Depending on your radio at 2m or 70cm the distance of your antenna above the chassis will determine it's effective gain. Your goal is to try and mount the antenna at both a 1/4 or 1/2 wavelength from the chassis for each band respectively. Or you can construct your own ground plane at the base of your antenna mount(s).

However, I doubt your interference is ground plane related due to your HT test. I'd suspect something else in your Jeep is the RFI generator. Specifically a poor ground to some electronic component. Anything from a powertrain controller (engine, body or transmission) to alternator, (generator if eTorque), LED lighting or even the Uconnect radio itself. A bad ground somewhere within the vehicle's wiring harness(es) is most likely your trouble.

Hate to say it but you may have purchased a lemon. Troubleshooting your wiring harness(es) will require technical knowledge of the schematic and pin connections for everything ground related.

Best of luck.
 

jeepoch

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@moonpup,

As a follow up. Maybe you can add a conductive flat strap to each compoment's outer case to the nearest hard (unpainted) bolt on the chassis. As you probably know, RF flows on the surface of conductors. That's why flat strap is much more effective at RF conductance. Regardless, this can potentially bypass any loose, shorted or broken ground wires or connector pins within any dysfunctional harness. In this way an unending trip to the dealership can possibly be avoided.

Try only one component at a time since you don't want to create a potential ground loop which can cause voltage differences and hence unwanted current flows. By doing this, at least you may be able to isolate the source of the RF interference. Vehicle manufacturer's spend a lot of time and effort in trying to minimize and eliminate any type of RFI, especially due to the ubiquitous cell phone usage in every vehicle nowadays.

Again only friendly suggestions, not a thorough understanding of your issue. I hope I'm wrong and that your interference can be more easily diagnosed.

Jay
 
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moonpup

moonpup

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Thanks for all the help and ideas!

I do have the LED lighting package with the DRLs. Obviously, I still have a lot of troubleshooting to do. The dealership I use is not too far from me, so I'll probably drive over there and talk to a service advisor and see what they say. It's possible I may not be able to fix it, and just have to wait for the next vehicle purchase :(
 

TX_Ovrlnd

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They should give it to the new tech who wants to be the electrical specialist, a few hours with a meter and pin-out guide might change his mind lol.
 

PocketsEmptied

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Have you tried turning off and unplugging things? Do you have anything plugged into the OBDII? On my JK I had bad RFI and it turned out to be the TrailDash plugged into the OBDII.
 

EbyCreek

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Having the same problem on a 2020 and 2021 JL Wrangler, so it’s not just your Jeep.
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