Strange CB problem - then it works, now it doesn't? - JKowners.com : Jeep Wrangler JK Forum
 
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post #1 of 4 Old 11-12-2010, 07:21 AM Thread Starter
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Strange CB problem - then it works, now it doesn't?

My setup:

Midland 1001LWX
18' coax with a male-male coupler and a 2' extension
Firestik K4A antenna stud mounted to a riser bracket secured behind the spare tire
Firestik quick disconnect
Firestik 4' adjustable fiberglass whip antenna

I have power coming right off the battery; one fuse in the engine compartment near the battery clamp, the other a panel mounted glass fuse mounted in the side of the console. I have RF snap-on chokes over each power lead (+ and -). I have a power noise filter mounted inline under the glovebox (made by RoadPro). Absolutely everything is soldered and shrunk.

Prior to my mishap I was getting a SWR of between 1.2 and 1.3. I assumed I could dial it in further and eliminate some of the superfluous noise I was getting - mostly through the antenna - by putting a ground lead on the antenna mount. As it is i'm getting good continuity from the bottom of the antenna stud to the mounting bolts that go into the tailgate.

Yesterday I was talking to some truckers on the highway. When I stopped keying the mike, my thumb slipped off and the button snapped outward. My CB went from having the usual background noise from an unsquelched signal to near silence. I was still receiving close transmissions (less than a mile), but everyone else on the channel now couldn't be picked up. I dead-keyed the mike and noticed my TX power normally all the way full was now only about 2/3 on the scale. I turned the radio off, got home, and took the mike apart.

These things are pretty simple; a switch and a mic element. No damage that I could see unless it's internal to the switch itself, which is unlikely (I hope?). Everything pivots smoothly and I put it back together.

This morning I hooked up the SWR meter and now I'm getting readings at 3+. I removed the antenna from the QR just for shits and giggles and the radio sounds the exact same in RX with or without an antenna (I did not transmit without an antenna, fyi)!

I'm at a loss at what this could be. I don't believe my lack of superior grounding ruined anything, as my SWR was favorable prior to the incident. I want to blame the mike but I find it hard to believe that because I didn't release the button gently on a mike in service for a week that something inside broke (that I can't see). All my coax connections are tight, and none of my coax can be damaged physically in any way. My power is good as the radio turns on, and there are no other symptoms of electrical failure or short.

Either it's the radio or the antenna has a short someplace. I simply can't think of any other diagnosis, can you? If it is the radio...does Midland take them back for repair? The thing is barely used!
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post #2 of 4 Old 11-12-2010, 07:24 AM Thread Starter
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PS: note: i do not currently have any ground lead going from the antenna mount to the body. My ground connection is purely mechanical: mount>bolts to tailgate>tailgate hinges>body. I saw no need for this initially because my SWR was favorable. Now it's blowing up and I have no idea why.

PPS: Installing a Midland in my TJ years ago I had no RF noise, no antenna issues, and a spectactular SWR with hardly any adjustment. This JK is just a pain in the ass all around!
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post #3 of 4 Old 11-13-2010, 09:42 AM
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Is it possible that you hit a big bump when your thumb slipped off of the mic? I don't think the mic has anything to do with your problem. With your swr going up the way it did I would say something has happened to your antenna system. Asking about a bump since this sort of happened at that time and is is possible that something broke in the antenna that has created the problem. To eliminate the coax and mounting system you should use an ohm meter and check out the shield from the radio to ground and center to ground with it connected at the antenna but off at the radio. You should get 0 ohms on the shield side and OL on the center conductor side if all is good. If you get <1 ohm on the shield side I would call that ok. If >1 ohm then you need to find out where the open is at. You might have to use a long piece of wire to check from the center conductor at the antenns base back to the radio connection if the others are ok just to be sure you don't have and open in the coax center conductor. Good luck.

09 JK 3.5 Rubincon express suspension 35" open country tires 9000lb superwinch member okc jeepthing club
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post #4 of 4 Old 11-17-2010, 02:50 PM
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Quote:
Originally Posted by wyldejackyl View Post
PS: note: i do not currently have any ground lead going from the antenna mount to the body. My ground connection is purely mechanical: mount>bolts to tailgate>tailgate hinges>body. I saw no need for this initially because my SWR was favorable. Now it's blowing up and I have no idea why.

PPS: Installing a Midland in my TJ years ago I had no RF noise, no antenna issues, and a spectactular SWR with hardly any adjustment. This JK is just a pain in the ass all around!
You're not gonna get a solid ground at the tailgate. That "could" be your issue. Run a temp ground to either tub or frame and recheck your SWR.
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