Poor radio reception with a "working" antenna

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Since I am still bearing the scars from replacing the antenna assembly on my 80, I agree with the point toward the end of Steve's checklist that a good place to check is for corrosion where it has the pointy contacts to ground on the fender. These are prone to corrosion of the zinc-alloy casting, which would definitely account for many of the symptoms that people mention.

If someone had ever attempted to fish the coax through in replacing the antenna assembly, there is the potential for cutting the coax. Done right, it won't happen, but it's tight back there. Not one of Mr. T's better days when that passageway was designed, but I'll take it with all the other GOOD stuff:)
Mike
 
I had the same issue with my '96; bought it in May. Reception was horrible! I replaced the OEM unit with a slick after market MP3 capable player; no luck.

So a couple of weeks ago I started looking at the actual antenna. Turns out the PO attempted an in line cable splice. The connection was bad. I tried to replace the antenna cable, however I could not thread it through the firewall. So I soldered the cable, and re-wrapped the shielding, and heat shrinked it all back together.
Works great now.
Hope this helps.
 
Same problem in my 94. I followed the cable leading from the antenna to the radio and it had, over the years rubbed on a edge of metal wearing it through. No option other than replace. I replaced my antenna with an aftermarket "whippy" antenna from Napa. I get great reception now, though the replacement was a gigantic PIA.
 
619TOY said:
In layman's terms:

  1. Turn meter on and set to ohms/resistance (highest scale if meter is not auto ranging)
  2. With antenna up and plug from back of radio removed, connect one lead of meter to the center pin of the antenna connector and the other lead to ground/outer conducter (this may be the entire body of the connector end or just a couple of spring loaded metal strips on the sides of the connector)
  3. Meter should not indicate any resisistance figure. Typically indicated by O.L. or 000 on meter screen.
  4. If you get any reading at all, the antenna or connector end must be replaced.
  5. If you passed step #4, leave the lead connected to the center conductor and connect the other to the antenna mast itself, outside the car.
  6. Now you should set your meter to its lowest ohm scale if not auto ranging.
  7. You should read next to 0 ohms (0-2 or so).
  8. If much higher than that, there is a problem which will probably also require antenna replacement
  9. If you passed step #8, reconnect one lead to the ground/outer conductor of the antenna connector and the other to the body/metal of the radio itself.
  10. Once again, you should read almost no resistance (0-5 ohms)
  11. If there is excessive resistance during this test, your antenna may need to be replaced but you should start by removing the antenna from the fender, cleaning the area where the antenna is grounded to bare metal and test again. There are almost always some sort of barbs on the back side of the fender part of the antenna itself. This is where the antenna gets it's ground.
  12. If you pass all of these tests, your antenna is good.
Click to expand...
1. Check
2. Check
3. Check
4. FAIL I read 1.8 ohms.

Of course now my mast is broken. I've removed it. I guess I'll try cleaning up the ground areas and testing again, or should I replace with an aftermarket flexy antenna using the old coax to fish a new line?

Nick
 
Nick,
you'll have a heck of time getting any cable through the existing passage if you don't use the old coax as a fish line to guide a new line through. The passage is very high up in the fender. You can see it from inside once you've taken the glove box out and perhaps some other stuff like a speaker and the audio amp.

The FSM tells you to take the dash apart and it is darn near that bad. Using the old coax, tape something to the end as you pull it out through the fender. The best thing to use is probably either an old piece of coax or a piece of stainless steel braided cable. It needs to be stiff enough not to kink when it goes through the passage.

You then need to tape the end of the new cable onto your fish cable and carefully guide things back in. I went OEM and the coax is attached to the antenna assembly, so you reverse the whole process. If you go aftermarket, it may be different.

The main thing if you've been having reception problems is to make sure there's no corrosion where the antenna projects through the top of the fender. Clean the hole of any corrosion, especially around the inside. There's a couple of projections/nubs on the top of the OEM antenna assembly nub and probably any replacement that are meant to push through the paint and contact the metal of the body around the hole. That gives you the ground. If that's been corroded, that's probably why your reception's been bad. The jam nut that goes over the antenna mast on top similarly has nubs, so when everything is tightened, you should be grounded well if the hole is cleaned properly.
 
I figure if I've gotta replace the cable, I'll use fish tape. It hasn't failed me before!;)

Thanks for the heads up on the areas of grounding concern. I'll clean 'em up, reinstall, and test again.

Do you know if everything is grounded fine, will it matter if the mast is installed (or not) for the resistance test? If so, will I be able to get away with a busted mast (metals intact, but the retracting plastic thingy is busted)?

I do OK mechanically, but electrickery is a bit cornfusing to me.:hillbilly:
 
The mast will need to be installed to get a good ground on the test, I suspect. The fitting the mast goes through at the fender is definitely a ground, with those little nubs that bite the fender where it goes through.

Then there is at least one bolt (maybe more, can't remember right now) that mounts the rest of the motor and assembly to the inside of the fender. That may or may not provide a ground. It might actually be isolated from the radio ground (where it goes through the fender) and be an electrical ground instead. Not sure.

I agree about electrical confusion. I've had lots of practice and even college credit in electronics. Must be why I switched to history. :doh: My wife has a MS in ECE. Between us, we mostly get things figured out when we need to, but only after at least some mild befuddlement.
 
Well, I cleaned up the ground locations. It doesn't appear that where the mast comes through the fender is a ground location. Lots of plastic, and the piece that secures the mast from the outside is barely magnetic and does not contact the body. However, where the bolt mounts to the fender appears to be the ground location.

I cleaned up everything including the fender, bracket, bolt, machine screws, and washers. No luck. Still crappy reception. I'm thinking about scrapping the whole deal for an aftermarket flexy-job, but I'm gonna check a couple other options first...
 
Hey,
I was just thinking about your project...

I ran out to pull the old ant assembly off the shelf in the garage. What you can see underneath is that the metal part at the top of the underside part sits at the angle where it contacts the underside of the fender. There are three nubs that bite the metal under there. There is also a gasket that goes all the way around, with cut-outs just at the locations where the nubs are to allow them to contact the fender. they are there, but you probably are just seeing the gasket.

Yes a real pain. What you should try doing is dropping the mast assembly enough to get to the top of it by pulling it back up from inside the fender. You'll have to loosen it from the back of the radio, as there isn't enough slack. But you can do this without jumping the shark to a whole new antenna install, if you still want to try for that to get access to see if there is corrosion to clean up on the nubs. Be sure to reach into the empty fender hole and clean that as best you can, too. This approach will let you hook the radio back up without too much drama if it works.

Why I was thinking about this was you comment about the fish tape. If you're talking about one of the springy steel ones, it probably won't work for this application. The turn is too tight and you're likely to kink it, as well as scratch the metal back there in the fender. A piece of coax is just about the right consistency for this job.

Hope this helps. It's a bear of a job, unless you got triple-jointed arms like a skinny space alien.:wrench::hillbilly:
 
Your problem is that the mast, or center conductor of the cable is shorted to ground. That's why you have bad reception. An antenna uses ground as a ground plane and to minimize interference by shielding the cable.

If the center conductor and the shield are indicating 1.8 ohms of resistance, even without a mast, there is an internal short in the antenna housing, cable or end. If you're not handy with this type of thing, you may have difficulty diasassembling the antenna and finding the problem. Replacing the antenna may be the best bet.

Unfortunately, improving the ground for the antenna can't remove the short.

While there are good flexible antennas, the typical Pepboys models generally won't work as well as the stock antenna. I'd replace it with another factory antenna, but I know that the price can be prohibitive.
 
Steve,
Your comment got me thinking. It could be that the issue is a failed provious attempt at installing a new antenna. It could be that the coax is damaged or cut. That might account for the problem. So could a mashed mast, I would think.

I gotta agree on the aftermarket choices. Despite my struggles with theory and practice, I do a lot of radio monitoring. I find that investing in a good antenna is definitely worth the cost. The aftermarket for quality auto AM/FM antennas is pretty barren. Anyone have a link to decent antennas?

Then there's the problem of what to do with the hole in your fender? You are very unlikely to find anything except the stock antenna that will fit it properly. I suppose you could cut off that part of a busted up stocker and use it to plug the hole, but it's not going to be pretty.
 
You must log in or register to reply here.

Share this page

Back
Top Bottom