RF Noise

[redpsy36]

I recently put a 29 LX in my truck as well as a mag mount Wilson 1000. With the truck not running, there is hardly any static even with the RF gain cranked up. But with the truck running, the only thing I hear is a popping or cracking sound that's relative to engine rpm. I disconnected the antenna and the noise automatically disappears so this tells me it's coming through the antenna. I have to turn down the rf gain to about halfway to make it go away with the squelch open.

I installed a noise filter on the power lines when I first got the CB but rewiring it without it doesn't change nothing
I've tried to ground the alternator case to the battery but it's the same.
Touching the whip of the antenna makes it not as loud.
Moving the antenna doesn't affect anything, as well as having the mag mount not touching the top of the cab.
It's a brand new battery, although the alternator is old but voltage when running is about 13.9 volts.

The truck is also a '99 so the grounds might be bad on everything.
If anybody has any tips or knows what would help, I'm all ears.

Thanks!!

 

[mmckenna]

I recently put a 29 LX in my truck as well as a mag mount Wilson 1000. With the truck not running, there is hardly any static even with the RF gain cranked up. But with the truck running, the only thing I hear is a popping or cracking sound that's relative to engine rpm. I disconnected the antenna and the noise automatically disappears so this tells me it's coming through the antenna. I have to turn down the rf gain to about halfway to make it go away with the squelch open.

Classic ignition noise. New spark plugs and wires may be in your future.

I installed a noise filter on the power lines when I first got the CB but rewiring it without it doesn't change nothing

Those only work for noise coming in via the DC power feed. A properly installed radio won't need it.

I've tried to ground the alternator case to the battery but it's the same.

Noise isn't coming from the alternator, and it should be well grounded to the engine block through it's mount anyway, but experimenting like this is a good approach.

Touching the whip of the antenna makes it not as loud.

You are detuning the antenna.

Moving the antenna doesn't affect anything, as well as having the mag mount not touching the top of the cab.

Sounds logical.

It's a brand new battery, although the alternator is old but voltage when running is about 13.9 volts.

I doubt that's the issue. But make sure your radio power feed is wired this way:
Positive wire to the radio needs to go direct to the positive terminal on the battery with a fuse installed within a few inches of the battery.
Negative wire to the radio needs to go to body ground close to the radio. No need to run it all the way back to the battery.
It's always a good idea to run a short ground strap from the radio chassis to the closest grounding point possible to make sure the case is grounded. But that's not causing your issue.

The truck is also a '99 so the grounds might be bad on everything.
If anybody has any tips or knows what would help, I'm all ears.

Thanks!!

There may be flakey grounds. Good idea to check for corrosion, especially where the negative terminal of the battery connects to the body.

 

[K5MPH]

Connect the radio power wire straight to the battery to see if that helps and or could be a bad alternator.

 

[cmdrwill]

Connect the radio power wire straight to the battery to see if that helps

And ground the radio neg lead to the body near where the radio is mounted. NOT back to the battery.
To me it seems to be bad sparkplugs and or bad sparkplug wires.

 

[redpsy36]

Plugs were replaced about 10,000 miles ago (about a year), and the wires a couple years ago but I may try to replace the plugs and see if that helps the issue. Thanks for the feedback!

 

[K5MPH]

Could also be bad bearings in the alternator they can cause Rf noise.......