Thought I'd bring this thread back to life since I have a similar problem now. Mods, feel free to move it to a new thread if necessary.
I had a Midland 75-822 connected to a 12V source directly to the battery and an 18' coax cable to a 3' Firestik on my Or-Fab carrier. SWR was never great, but hovered around 1, so I never bothered tweaking it to lower than 1. Worked great and served its purpose.
I installed late last night a Uniden Pro520XL last night to the same power source, but also added a 6' coax extension to my existing 18' coax since the 18' wasn't long enough to reach above the rear-view mirror.
Now I have engine interference when I turn the CB on. When the CB is on, I hear the revs of the engine as a high-pitch whizzing sound through the CB.
It was late last night and I didn't test it with the engine on until today. I plan to disconnect the coax altogether and see if it makes the noise.
Any idea what this could be and how to resolve it? Are there in-line filters for the coax or power feeds?
2018 JL Rubicon Unlimited, 6-speed, White
1985 CJ-7, 4-speed, 258 I-6, 3" Springs, 33" BFG AT, Gunmental Gray