So I installed a CB setup in my XJ - it's a Uniden Pro520XL with a 5 foot firestik antenna mounted on the driver's fender almost mirrored from where the factory radio antenna sits.

The only issue I'm having is a significant amount of interference from the ignition system when the engine is on, even though the coax cable goes nowhere near any of the plugs or really anything that gets a big jolt when the dizzy gives a plug a zap.

I'm assuming I need some form of shielded coax cable and/or shielded spark plug wires to make this interference disappear? I'd really like to be able to have my CB usable while on the road without having to stop, family of mine has had a few instances where they've been able to help folks out on the road and I'd like to be able to do that myself, I just can't hear anything with the engine on. The reason I am assuming I need one of the two shielded is because I installed the exact same setup in my stepdad's 2005 Ford F250 with the 6.0L diesel and it works like a charm with no interference at all, which I'm assuming is because we're dealing with constant voltage vs interrupted voltage - glow plugs vs spark plugs, two totally different systems between diesel and gas motors. One goes ZAP ZAP ZAP ZAP ZAP ZAP which overrides any other noise through the CB, while the other is.. Well, you get the point.

 

Make sure the ground strap from firewall to head is removed at the firewall end and the painted surface is scuffed up to bare metal. Me, I'd add a cable from that point to the intake manifold.

Tip 1 at www.cruiser54.com

 

I performed all your prescribed RENIX XJ tips about 5 months ago.

Replaced the ground strap with a giant cable, added an additional negative from the battery, etc etc etc etc.

Since you didn't bother to comment on the validity of the "spark interference" idea, I take it you believe that theory is bunk?

 

is your antenna isolated from the mount? Should be some plastic spacers in between the nuts and the mounting bracket. Grounding is you issue. Ive got two antenna's in the same spot on an XJ and a MJ with firesticks, and no issues. Have you Tuned the antenna with an SWR Meter? Hows your battery to block ground. Hows the battery to Chassis ground?

 

your excess antenna cable is looped in a coil? or how do you have it run?

if nothing else works, try looping the excess cable in a figure 8. i had a similar cb in my frontier and had to do that to clear up some noise. found it on a cb forum after lots of searching.

did you pop the cover off your cb and turn up the potentiometer for a little more power? if so, maybe its up a little high?

 

Radio noise from engine maybe, make sure the engine hood is grounded, my 1990 xj has a ground cable at the hood hinge for this purpose. my buddies 2001 xj has no strap on the hinges. So make sure your hood is grounded.

even back on the first jeeps they knew the need for body panel grounding if a radio was to mounted in the jeep...

https://www.armyjeepparts.com/p-380-...b-ajp-324.aspx

 

No. I just wanted to be sure you had good grounds first.
Ever set the SWR?

 

I have set my SWR, it was easy to do while the jeep was off. The hood does not have a grounding strap, though, that might be part of the problem. As for the cable, I do have it looped a few times in a figure-8.

I'll double-check the antenna mount, I'm about 95% sure it does have isolators.

I have lots of overbuilt grounding cable in this XJ. After reading Cruiser's Renix tips like the bible I know how important grounds are in these, so main ground locations were scrubbed to shiny spotless clean bare metal and 4 (or 6, can't remember at the moment) gauge black battery cable hooked up. Safe to say that battery to block is good, and battery to chassis is too, there's no doubt about that.

Edit: The mount does have isolators for the coax cable. The cable itself has its own built-in isolator, and there's a second one sandwiched on top of the mount - so there are isolators top and bottom, as Uniden instructed.

 

Okay, radio engineer here. That "theory" is fact. Yes, your spark plugs can generate a LOT of interference with radios. So can your injectors, which is the reason for the ground strap from the back of the head to the firewall. A STRAP will perform this function better than a cable, so since you are having radio problems, I'd start by replacing that huge cable with a huge strap. Get one from the auto parts store that is meant for a main vehicle ground. Get a monster like this one if it makes you happy:






That's where I'd start, but I would not expect it to be the total solution. Problems like this are often multi-layered.

The next thing is to check your ground to the radio. How did you ground it? That is critical. Please tell us where you grounded the radio and how you attached to a ground point.

Next, make sure you have good quality resistor spark plugs. We usually recommend old-school copper Champion plugs for your beast, but I don't know if they are a resistor plug or not. Just never looked. If they are not, you may have to deviate from the usual and find a compatible plug that is of the resistor type.

I know you believe you have addressed your vehicle grounds, but .....

The battery to fender ground is a poor design. It's a weak spot. The cable is not the problem, the attachment is. See this post or this post for what I did to improve mine.

Back to your main cables. Stock is 6, if you upgraded to 4 that's a nice upgrade. No reason to go bigger. It will not buy you any gains at all.

If all that doesn't help, you may need to consider new spark plug wires. These NGK wires claim to help, and I found a YouTube video that seems to agree.



And if all of that doesn't settle things down, we'll have to get serious. Do the basics above and let us know.

But please, do tell how you grounded your radio. Pics would be good.

 

Did you run the hot lead directly to the battery?

 

Here is the scoop on cb and grounding body panels...

http://www.k0bg.com/bonding.html

 

I had a Buick 300 v8 hotrod decades ago and experimented with home made solid wire plug wires. Not only did it mess my AM FM up badly but I think everyone within 10 blocks as well. But.. it went like a rocket with those things. Heh.

 

Hey folks, just wanted to let you know that it will have to be a few days before any more updates. Been super busy packing the house up for moving, and this weekend I won't be home at all. I'll check back in on monday!

P.S. I don't remember how I grounded the radio, it's been a little while since I installed it. I'll check monday.\\

Thanks for all the helpful replies!

 

Got back home and after having used the CB to communicate with family while caravanning on the road, I have discovered that the problem disappeared.

 

awesome!! the best kind of problems clears itself up