nrgizerbunny

I was so happy to find a cb that hides away nicely under my dash when I picked it up last year. I did a proper install with grounding all around, picked up a proper 4-5ft antenna and ran a good quality coax from the back to the front along the roll cage ending up by the drivers feet. The antenna has not been tuned yet.
I hear a pulsing sound about 1/sec and it doesn't matter if I'm downtown or 500km from the nearest building. This was there right from the first time it was installed and not something new.
Here are some of the troubleshooting I did. I would love to hear if anyone has suggestions for next steps.

2008 wrangler unlimited rubicon with factory gps/entertainment setup and an electric rust inhibitor.
- ignition off, direct from the battery: no pulsing noise
- ignition on, direct from battery, engine off: pulsing noise is there
- ignition on, direct from battery, disconnect electric rust inhibitor: pulsing noise is there
- ignition on, direct from battery, disconnect radio/gps/entertainment unit: pulsing noise is there

thanks for your help and suggestions!

Mark Doiron

While at Easter Jeep Safari I started having a pulsing noise breaking the squelch on my CB. I was with two other JKs (TORN and Highrlr) and they didn't hear it. Long story short, it turned out to be my laptop computer, which I'd plugged into an inverter to recharge. So, keep doing what you're doing (unplugging things/fuses to see what happens) until you track down the culprit. Look most suspiciously at anything that's not stock.

JKGuy

Noise on an HF AM radio is NOT uncommon. If it's just a slight noise I'd just squelch it and not worry about it. If it's very bad the most likely cause is the fuel pump, but noise in a system can be a true gremlin.

I have very little noise in my radio but I know others with a similar system that complain about it. You can try putting torrid coils on the power lines as well, or even twisting them to try and damp it down. Also make sure the antenna mount is well grounded.

Good luck

AK4Dave

yes...........fuel pumps can be real bad noise makers sometimes.

nrgizerbunny

Thanks for the info.

Unfortunately its not the fuel pump. Everything is shut down and the ignition is the only thing on. I pulled fuses until everything is off (minus the Jeep computer) and its still there. I'm suspecting its a loose ground on the computer or the shielding wasn't put in place.

The pulsing or popping (1 or 2 per sec) is pretty bad. Even with the squelch all the way up, I can see the bars dance to the rhythm. Of course, its not good in that setting since the signal is "muted". I can find that sweet spot where the pulsing goes away but then the transmitting radio has to be 2 ft away.
The antenna is well grounded (just shy of welded onto the body). I took a grinder and cleaned up the metal. I did the same thing with the base unit thinking thats not grounded properly. No change yet.

I don't have too many custom things installed other then Linex (which shouldn't matter) and a silly electric rust inhibitor (I removed that bad boy)...what a waste of money that was. Thank God they threw it in for $50.

I tried an OLD radioshack CB last night and it worked fine with the same power source and antenna. I wonder if I can gut the cobra and use some silly putty, duct tape and a paper clip to pile the radioshack goodness into the same casing. lol

Anybody in the Oakville/Toronto area with the same setup who is willing to do a quick test swap, for S&G and a coffee?

oh how I hate electrical/radio problems!

Mark Doiron

You're doing exactly what I'd be doing. Failing that, see if wherever you bought the radio won't replace it--it sounds like there's an internal problem.

Weeds

I have the same problem. I will try unplugging the attenna.

Weeds

The noise went away when I unplugged the antenna.

Does the antenna wire need rerouted?

How do you block noise coming through the antenna connection?

Mark Doiron

Maybe a quick and dirty test will provide a clue: Connect up a different antenna with a different cable. See if this different hardware, presumably not lying anywhere near the permanently installed hardware, suffers the same problem.

BTW: If the second antenna continues the problem, then that RF noise that's interfering with your radio should be picked up on other radios nearby. Try parking next to someone else and see if their radio starts picking up your noise generator. If it does, then you need to isolate that noise source. Try ignition on, pulling different fuses to see which one causes the noise to stop.

Also: I've seen radios exhibit unique noise problems only when the antenna was connected--not because the problem was coming in from the antenna, but because the radio needed that last bit of impedance connected to exhibit the noise. I don't think this is likely in your case (because it works okay without the ignition on), but still wouldn't be totally surprised to learn down the road that the radio is bad.

Weeds

Thanks for the ideas. I have a magnetic antenna I can try.

The noise starts when you put the key in the ignition.