Jedi Knight

Thank you very much for the offer. I do have 2 friends with CBs. One has a hand held and the second has a radio shack CB. I asked both of them if I can borry them to test to see if the noise is the same on both. I don't know anyone with a Cobra 75. I will try those two and see what happens. I will also try to see if I can replace the CB power and ground cables with a thicker and hopefully shielded cable. Should that not work, my next plan is to see if i can get ferrites and put them on the power and ground cable for the fuel pump. The hunt continues....

RichRock

It doesn't seem like you should have to go to extraordinary measures when this same system has worked well in other jeeps like yours. I just got mine delivered yesterday (awesome delivery speed btw. I ordered on the weekend), so am watching your experience closely. Probably won't get to it until the weekend, as I am knee deep in a home improvement project right now.

Jedi Knight

Last night I tried my friends handheld. No noise. I installed Ferrites on the CB power leads close to the CB and it did not help. I did get lucky and found what I believe is the cause. I think it is the ignition system. When I turned on the key (But not start the engine), there is a clicking sound that is coming from the top of the engine. The noise on the CB occurs when that clicking sound is happening. If you wait, the clicking sound will stop and thus the noise on the CB will also stop. I did not notice this before. Also in my troubleshooting before, I had the passanger side door open so I can get to the CB and turning on the ignition from there. Last night when I was troubleshooting I had the driver side door open. This was a good thing because when the "Hey you left your key in the ignition" beep was going off, I could hear a hint of the ding through the CB. As this point it is very dirty power. I tried running power from different parts of the Jeep and it was all the same. Since the noise filter I bought didn't really help, I've decided to build my own. I found a good link on the net for instruction for a homebrew version. That can be found here:

Homemade Noise Filter

This will be my next course of action. I'm getting ready to go to Florida on vacation next week so it will probably wait until I return. Just wanted to keep everyone in the loop. I am so anal about finding the root cause. I'm one of those people that can't rest or let it go until it's fixed I guess that's why i'm a Systems Engineer

RichRock

It's your ignition system? Did you modify it in some way? That shouldn't be the cause if other JKs have successfully installed this without the noise your getting. Also, when you say the handheld cb got no noise, I don't understand how that is relevant if it wasn't hooked into your system. It's a handheld right?

Why don't you accept the offer to borrow the Cobra 75, hook it in and see if it works? If is does, then your unit is defective and they should replace it. If it works the same, then wouldn't the cable be the next logical thing to swap out?

I am going to start tackling the install of my Cobra75 this evening (if it cools down a little, since I can't do it in the garage (no room)). Mine is from Ultratech also, but I am adding a heavy duty Cobra spring, and a Cobra external speaker. Otherwise I think it's the same as yours.

I will advise of my progress later.

Jedi Knight

No mod at all. We have troubleshot it by process of elimination according to the sounds.

Correct. I wanted to see if the interferenace was from RFI hitting the wire from the outside or if it was traveling through the power wires. Using the handheld allowed me to rule out ootside the wire RFI

I will accept the offer. I want to try a few more things before I borrow the other Cobra 75.

I read your other thread and am glad to hear that you did not get any noise. I'm leaving for Florida on Saturday so I will won't have time to work on this until I get home. Hopefully it will be solved soon and I can move on to the next challenge.

RichRock

Sorry I didn't find anything that would help you. Thanks for the info re photos. I am signing up on My.Project-JK right now.

Your posts made me go real slow thru the process. I hooked up the system and ran it at least 3 separate times at 3 phases of the install before closing everything up. My best signal of course was when I simply ran the cable straight across the seats, out the front door and into the engine bay.

When I decided to try and connect to the back of the power outlet I was very wary about running the wire behind the center stack. I tried to stay away from speaker magnets and fan motors as much as possible, but there isn't much room to maneuver.

Have a safe trip. Glad you are going to try the "loaner" cb. Good luck with that.

Jedi Knight

Ok I finally have time to resume working on this now. I have tried another brand new Cobra 75 unit and it is doing the same thing. At this point i'm making a homemade noise filter and will try that. Just wanted to keep everyone in the loop.

RichRock

That sucks. Did you try relocating the cable? I know you tried a lot of things. But mine continues to work fine. I can't figure out the difference.

Jedi Knight

Yup. No dice. I can't figure our the difference either. If this noise filter i'm building doesn't work, then I might see if I can build a power conditioner to purify the power and run a power block off of that. One way or another I get it fixed. It no longer business with this CB, now it's personal

climbr

Did you solve your problem? Any new avenues?

I am having this exact same issue with my install now, just a different mount:
Cobra 75 (in same location), Teraflex mount with FireStik II 4ft and Fire-Ring cable.
I've got SWR at 1.4
The noise is just constant on all channels at 3 on the display meter. When you rev the engine, blinker, fan, all make more noise. I only get feedback when the ignition is on, and alittle worse when the engine is on. The noise drops to nothing if I remove the antenna connection's outter-ring while the engine is running.

How much noise does everyone else get with the Cobra 75? This normal? Should it be dead quiet (no RX signal) or is there always some noise?

My only idea is if the Fire-ring ground side is not making contact on the Terflex mount because the mount has been over-powder coated and not making a true connection to the gate (and I did run a ground wire from the body directly to the gate metal.)