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Old 10-21-2012, 07:53 PM
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WinterParkJK's Avatar
Join Date: Aug 2012
Posts: 51
Messed up my CB install somehow...please help!

Hey folks,

I rigged my CB (Cobra 75) to my 2012 JKU this weekend following the outstanding post here by Smitty4x4. I think I failed on the final step though. When wiring the power for the unit, I opted to connect to the cig lighter since it shut off with the ignition (don't want to risk draining , battery if I accidentally leave it on). By doing so it seems I created a ground loop. What suggestions would you all have to fix this?

I think I'm getting a ground loop because I have fierce static (running or not) and can her a rhythmic pulse every 1 second or so. If I mis-diagnosed, let me know what else I may have done wrong.

Specifically I'm looking for suggestions on where to run the wires as an alternative. I should tell you upfront that going through the firewall isn't an attractive option for me.

Thank you!

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Old 10-21-2012, 08:44 PM   #2
Join Date: Mar 2011
Posts: 864
You have a couple choices,

1) Run power directly to the battery. That's the best way for a clear signal and to not pick up ground noise. Unless transmitting CBs pull very little power.

2) Run a relay to power the cb pulling power direct from the battery. Run the trigger for the relay from the cig lighter or other switched source.

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Old 10-21-2012, 09:33 PM   #3
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While going through the firewall may not be attractive to you, the other ways of isolating noise are much more invasive.

Running straight to the battery (with a fused pos) is easiest. The draw of a cobra 29 is 1.5A Max output @ full Modulation TX, 1.2A @ full volume RX, and 0.3A standby. In other words, if it isn't make noise it can be on for about 7 years before it kills a standard car battery, in theory at least. In reality I'd highly doubt overnight would ever be a problem - unles you live by the highway and would receive all night.

You can run a wire from an empty ign hot fuse or the cig lighter to a relay causing the radio to be both straight wired and ign controlled.

So, what Iceman said, lol.
“Coming of age in a fascist police state will not be a barrel of fun for anybody, much less for people like me, who are not inclined to suffer Nazis gladly and feel only contempt for the cowardly flag-suckers who would gladly give up their outdated freedom to live for the mess of pottage they have been conned into believing will be freedom from fear.”
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Old 10-21-2012, 09:39 PM   #4
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Location: Black Hawk, CO
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Check this post out, specifically my post #15 You really should wire it directly to your battery, that is about the only way to avoid the feedback issues you are experiencing. If you are worried about leaving it on, your best option is with a relay wired to your cig socket. Getting through the firewall to your battery won't be terrible, if it's an automatic, you can go through the clutchplate (place where the clutch cable would go through if it were a manual trans. If it's a manual, there are several unused grommets that can be utilized, search the forums for amp installs for ideas.

Do it right and you won't regret it!
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Old 10-22-2012, 05:58 AM
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Join Date: Aug 2012
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Thanks for the good feedback and quick replays. I appreciate the info.
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