C3 Antenna Cable Replacement

[Robert S.]

On my 74' my FM is fine and my AM is so weak I only get a little out of one station at full volume. I made up a dummy antenna which I plugged in at the radio and AM reception got much better so am assuming I will need to replace the antenna cable.
I am looking for comments and experiences on this task. Will I need to pull back the drivers side dash panel? How is the cable routed (under the sill plate?). Any recommended sources for the cable (Paragon)? I searched he archives and did not find anything on this subject for C3's.

[Jack H.]

Re: C3 Antenna Cable Replacement

The routing path for the antenna lead-in cable follows the LH door sill. You pull up the carpet adjacent to the driver's door sill plate and you'll find the antenna cable following the path of the rear wiring harness.

Replacement radio cables are available. Most of the major catalog houses list them. It's NOT a huge job and you do NOT have to pull the dash.

The cable often suffers internal damage when it's bent too severely. That lead wire inside is VERY thin. Plus, the damage 'can' be isolated to just the bananna plug end at the radio chassis (prior owner/mechanic removal/insertion stress).

[Don G.]

Re: C3 Antenna Cable Replacement

I seem to remember that at some point, GM routed the antenna cable through the console using a shorter cable. Be sure your replacement is of the longer design for routing through the door sill.

[Harmon C.]

Re: C3 Antenna Cable Replacement

I seem to remember that at some point, GM routed the antenna cable through the console using a shorter cable. Be sure your replacement is of the longer design for routing through the door sill.

You are right and the short cable can only be used when replaceing the carpet in all shark years.

[Terry M.]

Re: C3 Antenna Cable Replacement

Or removing and reinstalling the carpet.

[Patrick H.]

Re: C3 Antenna Cable Replacement

Yup.

I do not "think" that the longer cable is currently available, so you may want to think hard about whether or not it is "worth" replacing the cable just to listen to AM.

I know what I would do, but...

Patrick

[Kenny C.]

Re: C3 Antenna Cable Replacement

Robert
Frankly before I went to the trouble of pulling the cable out I would remove both ends and perform a continuity test to make sure its even bad. Also I would be checking the grounds at the mast mounting plate and at the radio itself. AM signal is much more sensative to grounding than is FM. And as it was suggested if you find that the cable is bad I woud check the ends to see if there is a break at the tip that is repairable easly, could be much more time and cost effective than running a new cable.
Kenny

[Jack H.]

Re: C3 Antenna Cable Replacement

Well, then you got lucky... The presumption that each/every antenna lead-in cable exhibits end to end continuity isn't always true.

Some cables are intentionally built with internal overload capacitors installed. Huh, why?

Well, the antenna dipole is capacitively coupled to the radio's 1st stage amplifier. Under 'just right' conditions, it's possible to 'swamp' or 'saturate' the amplfier with excessive received signal strength.

Ever been driving in a car when the radio 'lost it' going into a constant HUMMM when you drove beneath or along side an overhead AC power line? The interfering hum was the result of unintentional 60 Hz power line broadcast(s) overloading your radio receiver.