Noise in FM audio and on CB (1 Viewer)

[RyRoRyan]

I am trying to figure out what could be happening here. When I have my radio on FM mode, I can hear small "clicks" and a small amount of engine hum. If I turn the squelch down on my CB, I can hear the same on it as well. The antennas are grounded and all the wiring is done correctly. The CB and the Radio arent even on the same fuse. If I changed modes on the stereo and use my USB input or bluetooth...anything other than FM it is quiet and sounds great. I dont know where to start on this one. I dont THINK it is power based because it is great when using a source other than FM, however what is going to cause something to be injected into both the FM band and the CB band?

 

[Dave 2000]

Clicks tend to be from HT leads, whines from alternator. Plug leads getting old?

Sometimes an earth braid from bonnet to bulkhead can help?

Regards

Dave

 

[Cass007]

Does the pitch change as the rpms change ... higher pitch with higher rpms?

 

[stu8319]

I had noise when I was running some LED headlights. Went completely away when I swapped back to regular bulbs.

 

[RyRoRyan]

Yes the hum pitch changes...I know this to be common with aftermarket amps and the grounds being off a bit. However I am using a ground loop isolator between the signal and the amp and like I said, when I am not on FM mode, the system is quiet. I cant hear ANY engine noise, no clicking no nothing. Only when I put the source into FM does it generate this noise and like I said, my CB radio can pick it up too when the squelch is turned way down.

 

[Dragos80]

"Ground control to Major Tom"

Anyway...
You (the radios) are not properly grounded.

 

[Mattyboy]

You need a ground loop isolator.

 

[RyRoRyan]

Ill have to look at all the grounds...I am wondering if the dual battery setup (National Luna) could be causing a problem.

 

[Rivman1243]

What about the factory antenna?

 

[Dave 2000]

Ill have to look at all the grounds...I am wondering if the dual battery setup (National Luna) could be causing a problem.

I use the NL gear with no problems FM or CB. Does the click stop when the motor is shut down? Dows the click increase with revs?

Regards

Davr