Electric interference with GMRS

[rollcage]

I have this noise under the hood with the key on. Its always been there since day one and I've never given it any thought until I've started trying to install GMRS. I moved power and ground directly to battery individually and together and it still gets picked up and transmitted by the radio. I hooked to radio to a spare 12v battery i have and the noise is gone. Key off no noise, key on engine on or off its there. Any thoughts on how to get rid of it?

Sponsored

 

[dstevens]

Sounds like the throttle body. They use a PWM signal to a DC motor and they always make audible noise; I'm not sure if you are talking about electrical noise as well.

Route the radio wires away from the throttle body / ECU, twist power and ground together, and if that does not work a ferrite core would help.

 

[rollcage]

I've had the radio in several different locations. Driver footwell, passenger seat, even moved under the hood for various wiring experiments. I will try twisting the power/ground wire to see if it helps. That exact noise is being heard over transmission and reception on the gmrs. I've also ordered a nosie filter. may try a ferrite core too.

 

[dragoneggs]

You can try to use a ferrite core but ideally you need to should find the source of the EMI.

Don’t know how it would work in your case (I have done this in my house setting up Ham radio) but if you have an old AM transistor battery radio, set it to a low frequency and move it around under the hood and see if you get any increased static in a certain area. That would be a source of interference.

 

[rollcage]

Some internet crawling and I found threads pertaining to this same noise being from the throttle body. So If I know thats the source of the interference is there somehting I can do to limit it here? Should I just be looking a shielding the power wires?

 

[JLeco2022]

it sounds like you have bleed over, we use to trace these sounds over transmissions on blackhawks when i worked on them in the army. most likely you have a weak shielding that is bleeding over the positive or negative wires giving you what you are describing. there are ways to make the noise less with addon parts, but to be honest the best way to fix this the correct way is to slowly isolate the electrical components until the bleed is gone, then troubleshoot said problem. it can be alot of work. however if you don't, whatever part or wiring is causing that problem will fail down the road

 

[rollcage]

This seems to have corrected the issue. I know its best to insulate source of interference but in this case I dont know how to insulate the throttle body.

 

[Whatevers]

I hope this fixes mine. Reception is fine.
Transmit however:
Key OFF fine
Key ACC fine
Key RUN BUZZ
Engine running BUZZ.

I've tried this filter

Ferrite beds, RFI shielding. Power to the Aux always on line and grounded to the frame on the passenger side, to routing power to the battery with a ground at the frame or the battery neg.

Sponsored