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Discussion Starter #1
I just finished installing some roof-rack mounted led lights. They are hooked up to the Rough Country MLC-6 switch pod (similar to SPOD). Whenever I turn on the lights, I get a bunch of static on the radio. My bumper light bar does the same thing but less extreme.

Facts:
CB is getting power from behind the cigarette lighter using an adapter harness. Since this is sometimes not as clean, I tried routing the wires directly to the battery but the issue remains.

When I disconnect the antenna coax from the back of the CB, the issue is gone.

The CB itself is mounted in the passenger footwell, and the coax is routed along the passenger side floor to the tailgate. The antenna is mounted on a TF spare tire mount.

Disconnecting the antenna also solves it.

Swapping to a different antenna, the issue remains.

So it would seem the noise is coming in from probably a switching regulator in the lights causing noise on the 12v line, and jumping over to the antenna and entering the radio thru the coax.

Can anyone recommend a better routing path for the coax to avoid this issue? Is there something else I should try?
 

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Discussion Starter #2
I just finished installing some roof-rack mounted led lights. They are hooked up to the Rough Country MLC-6 switch pod (similar to SPOD). Whenever I turn on the lights, I get a bunch of static on the radio. My bumper light bar does the same thing but less extreme.

Facts:
CB is getting power from behind the cigarette lighter using an adapter harness. Since this is sometimes not as clean, I tried routing the wires directly to the battery but the issue remains.

When I disconnect the antenna coax from the back of the CB, the issue is gone.

The CB itself is mounted in the passenger footwell, and the coax is routed along the passenger side floor to the tailgate. The antenna is mounted on a TF spare tire mount.

Disconnecting the antenna also solves it.

Swapping to a different antenna, the issue remains.

So it would seem the noise is coming in from probably a switching regulator in the lights causing noise on the 12v line, and jumping over to the antenna and entering the radio thru the coax.

Can anyone recommend a better routing path for the coax to avoid this issue? Is there something else I should try?
Well, moving the antenna so the tip is above the roof line seems to have made it better, but not entirely.
 

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An inadequate RF ground at your antenna mount could be contributing to the noise. What SWR were you able to obtain when you tuned your CB antenna?
 

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I have been chasing the same thing with a 50". I have taken both the CB & the lights directly to the battery. SWR of 1.3 IIRC, I have a grounding strap from the tailgate to the tub and scraped off the powder coat the bracket. Nothing helps. I have had 2 50" lights 1 with 100 3 watters and now 50 5 watters, both LifeTime LEDs. The 50x5 is quieter so it appears the number of LEDs is what makes it worse. I also run windshield pods and they barely induce any noise, again the number of LEDs seems to be the culprit.
 

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Discussion Starter #6
An inadequate RF ground at your antenna mount could be contributing to the noise. What SWR were you able to obtain when you tuned your CB antenna?
I got 1.0 SWR on channel 20. I just tried using jumper cables from the antenna coax connector to the battery negative... Didn't help. I'm thinking it's noisy LED's like you said.
 

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Discussion Starter #7
What I should have mentioned above is some cheap LED lights, especially light bars with made with cheap LED lights, are just going to be very noisy, electrically speaking. When fighting electrical noise that started after installing LED lights, you may be fighting an unwinnable battle if the manufacturer went cheap on them.

https://www.google.com/search?q=Are+some+LED+lights+electrically+noisy&oq=Are+some+LED+lights+electrically+noisy&aqs=chrome..69i57.9523j1j8&sourceid=chrome&ie=UTF-8
Do you think an LC filter on the lights would help?
 

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Discussion Starter #9
Hard to say but I'm guessing not since the noise is coming in via your antenna and not through your power lead.
How about taking the lights apart and trying to construct a faraday cage around the driver board? It would have holes for the led chips themselves, so I'm not sure how effective it would be...
 

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Discussion Starter #10
(post created in error)
 

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How about taking the lights apart and trying to construct a faraday cage around the driver board? It would have holes for the led chips themselves, so I'm not sure how effective it would be...
I think I'd chalk it up to experience and cut my losses by selling the noisy light bar and buying one with better quality.
 

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Discussion Starter #12
I'm considering that, and I'm willing to pay for quality, but I just can't justify Rigid's prices. I mean, to me they are simply ridiculous. I've also found some threads where guys are having the exact same issue with "high end" LED lights. I think the only way to truly solve this is by switching to a different lighting technology other than LED.
 

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Discussion Starter #13
Some progress tonight. I disconnected just the left light, and the noise was mostly gone. (By "mostly gone" I mean that I can see on the display that the noise level slightly increases when the lights are turned on, but it's what I'd call acceptable and below the squelch level where it had previously occurred which was a setting of 4 on a scale from 1-7). I got excited thinking I could just exchange the light, but thought I better do more troubleshooting first. I tried swapping left and right lights, and the noise was still mostly gone. Ok, weird. Then I put them back to their original positions and the noise was still mostly gone. wtf? I guess it was a bad connection? I did put some connectors on these lights since they came with bare leads. I'll try them again over the next few days and see if they continue to behave or not.

Next problem: My 12" bumper light bar seems to be biggest noise culprit now. It's wired directly to the relay bank, with no connectors in between, so that one may be harder to diagnose. I disconnected and reconnected the wires at the relay, and saw no improvement.

The next highest source of noise is something related to engine rpm. At a squelch setting of 2, I can hear noise that corresponds to engine speed. I'm guessing either the alternator or spark plug wires.

If I can solve those 2, I would call it a success.
 

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None of the Jeeps in your signature have spark plug wires. If it's static, it could be that someone installed non-resistor spark plugs in hopes of better performance which non-resistor spark plugs won't help with. Factory spark plugs are resistor type, used to prevent spark noise/static out of the computer and AM/CB type radios. A whine noise would be more of an alternator noise. Such noise can also be caused by taking short cuts when powering the CB like connecting to the cigarette lighter wiring. 2-way radios like CBs and ham radios should always be power directly from the battery or 12 volt input lug inside the power distribution center.

This is where your JKU's 12 volt input lug is which is a great place to power a CB/ham radio from. It is connected directly to the battery via a short heavy gauge wire.
 

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Discussion Starter #15
Discovered something interesting tonight. After I re-mounted my roof lights, the CB noise was back. Frustrated, I decided to remove the lights again. As I was loosening the nut that attaches the light to the bracket on the roof rack, the noise started to go away. As I raised the light off the bracket, the CB noise was gone. So now my best guess is that the noise from the lights might be flowing through the roof rack, into the antenna. Maybe.

I know that I can only glean limited information from using a multimeter to test for conductivity, but I'm seeing that the brackets don't have DC conductivity to the rest of the roof rack. Not sure if that is really useful information though since RF is like magic (i.e. there are ways to get a DC open and an RF short, or vice versa.)

There are a couple things I can think to try: First is to improve the grounding of the roof rack itself, and also put ground straps across individual pieces of the rack so each piece has conductivity to every other piece. After that's done, I'm not sure if it would be better to intentionally try to ground the light housings to the roof rack, or go the other way and try to isolate the lights using a nylon washer, similar to the CB antenna stud. The quick fix would be to just isolate the lights from the rack and call it a day.
 

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Discussion Starter #16
The lights are on hold for the time being while I figure out the engine-noise issue on the CB.

I went on a jeep run Saturday and it seems like the engine-related CB noise is getting worse. I now have to leave my squelch on a setting of 4 or 5 (max is 7) to overcome the on-board noise. I don't like this since I'm effectively reducing my effective range. So when I got home I permanently routed the CB power & ground directly to the battery instead of the cig lighter. This made no difference whatsoever. At this point I'm thinking maybe the coax is damaged or the routing path is just bad (parallel to other wires for too long). So I ordered some RG8X coax (currently using RG58) that I will hook up temporarily, and if that works then I'll try tucking it under the carpet (while removing the old coax) and see if it's any better. If it gets worse again, then I'll know it's the routing.
 

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CB interference issues can be maddening.

I have a couple of cheap, round 27-watt LED lights on the front bumper of my 2003 TJ which I mostly use as daylight running lights and occasionally as work lights at night, along with another one in the rear as a work light and one inside for interior lighting. None of these LEDs cause any CB interference at all.

When I need a CB in the Jeep, I place a 35-inch magnetic-mounted K30 antenna in the middle of the hood just behind the "handle." I plug the Cobra 19 radio into a 12v port on the dash. There is no interference at all with this set-up, and it communicates very well in the field with other members of my party and on the road with truckers.

So CB interference is not an inherent Jeep engine problem or LED problem or 12v port problem. It's just one of those individual problems that needs to be ferreted out. Good luck in your quest.
 

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Discussion Starter #18
Still waiting for the other coax to arrive, but tonight I tried powering the CB with a completely separate battery. Engine noise is still there.
 

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Discussion Starter #19
Tried the replacement coax. No improvement in engine noise coming thru the CB. Ugh.

The ONLY thing that seems to work is pushing the "LO/DX" button. Here's an excerpt from the manual:

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Adjust Radio Sensitivity (LO/DX)

Noise caused by strong signals from nearby

channels may be heard. The LO/DX settings

(LOCAL 1 and LOCAL 2) will reduce this noise by

reducing the radio’s sensitivity. If LOCAL 1 or LOCAL 2

do not display, noise levels are not reduced.

1. Press LO/DX. LOCAL 1 displays; noise levels

are reduced.

2. Press LO/DX again. LOCAL 2 displays; noise

levels are further reduced.

3. Press LO/DX again. LOCAL 2 goes away;

noise levels return to normal.

Occasionally, you may want to listen to

weaker signals (for example: receiving a distant signal). In that case, do not reduce

sensitivity levels.
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I assume this is equivalent to RF gain. If I turn on Local2, I can turn down the squelch to the lowest setting and the engine noise goes away.

I haven't been able to test how this setting works when someone else is actually trying to talk to me.

I have tried everything I can...
-2 different antennas
-Different coax (and routing it differently)
-Power source (direct to jeep battery, separate battery, and cigarette lighter power)
-Ground strap on the antenna mount
-Snap on chokes

I give up. Maybe the receiver is just overly sensitive.

I suppose problems like this are part of what motivates people to use ham instead of CB!
 

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Ham equipment is prone to interference like is CB. There is no inherent reason why the CB 11 meter band is better or worse than the Ham 10 or 12 meter bands. The difference is just the frequency being utilized.
 
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