1. Home
  2. Automotive Technologies
  3. radio antenna problem

radio antenna problem

My 1996 Jeep Cherokee Sport just developed a problem. Overnight the radio went from being pretty good to one that gets nothing but static. The tape player works fine. My first thought was the antenna came unplugged from the radio. I pulled off all the plastic crap and pulled the radio. The antenna was plugged in. I stuck a piece of insulated wire into the female antenna connection and got good FM but no AM reception. So, I assumed the radio is OK and there must be a problem with the coax going from radio to the antenna. I measured the resistance from the tip of the connector that goes to the radio to the outside antenna and got high resistance - several megohms. The resistance from the outside of the coax connector to ground is high as well. Is there any solution other than replacing the antenna coax? My guess is that the resistance for both should be only a few ohms. Right? Is it reasonable that the antenna coax would go bad like that overnight? Is the coax one piece from radio to antenna or could there be some connection that has come lose? How hard is it to replace the coax (without completely removing the entire dashboard)? Oh, there have been no accidents or traumatic jars to the car other than a few holes in the road. Right now I'm driving around with all the plastic in the back seat and my jerryrig antenna wire laying on the dash. That's OK with me but my bride doesn't like it.

Reply to
hebintn
Loading thread data ...

Tearing the dash out versus getting a new bride?

hmmmm... that's a tough one.

Reply to
Simpson

"hebintn" schrieb im Newsbeitrag news: snipped-for-privacy@t54g2000hsg.googlegroups.com...

Depending of which antenna type is installed. Some wipe antennas could be equipped with an amplifier, in this case a high resistance between the tip and the wipe could be possible. If not it should be zero ohm, and in case with an amplifier it should be fed. Resistance between shield and chase should be zero in booth cases.

Regards,

Ralf

Reply to
Ralf Ballis

Here is a big issue: antenna lines are NOT made of coax. They are not actually operating as transmission lines at all, but are designed like scope probe cables with a super high-impedance source and load. (This is because the antenna is a stub much shorter than a quarter-wave, driving a high impedance input on the radio.)

The cable is shielded, but it has a VERY thin center conductor in a loose internal tube. That center conductor can be easily broken at the connector on either end, and it can break in the center too.

A "Fox and Hound" telecom cable tracer can help you find the break. Otherwise you will have to pull a whole new pre-terminated cable assembly from the dealer in there.

--scott

Reply to
Scott Dorsey

Thanks folks. I learned a lot. Since the only test equipment I have is a VOM it sounds like the only solution is to buy an new one and try to put it in. I'm guessing from Scott's post that the existing one is broken somewhere. Now I'm starting to wonder if there is any harm to the radio in just leaving the "wire" antenna in. That may be the easiest and most cost effective. This is my car not the wifes and I could care less if there is a wire hanging out on the dash.

Reply to
hebintn

There is something about Jeep Cherokees and radios... Very few older ones work well at all. Both ones we owned quit bringing in FM. AM and the tape still worked.

I personally would be tempted to use your fix.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail > Thanks folks. I learned a lot. Since the only test equipment I have
Reply to
Mike Romain

It's not hurting anything, but it would drive me up the wall, personally.

--scott

Reply to
Scott Dorsey

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.