1967 coaxial cable help

[J W.]

Trying to get information on 1967 coaxial cable. My radio and speaker have been checked and refurbished by a professional and all is up to par. The reception on FM/AM is poor , low volume and only 2 stations. With an off the counter antenna it works much better, better volume and more stations. You cannot check out the coaxial cable because it is capacitor loaded plus the capacitance is in Picofarads. Has anyone had any experience in where the capacitor is located on the cable and can it be modified or repaired? Also what was the original Ohm rating of the factory cable?The cable was replaced in 2005 by the previous owner and has no manufacturer, ohm rating or part number. It appears to be a correct looking reproduction like most venders sell. To make matters worse it appears to be located under a foil/rubber insulating material under carpet. Impossible to remove, therefore my quest to possibly try to modify or repair existing cable . I will also add that the existing cable has been checked for any grounding in the coaxial shield as well as the antenna parts on the car and all checks ok. Thanks in advance for any help.

[Thomas H.]

Re: 1967 coaxial cable help

Assuming you removed the car antenna cable from the radio and plugged in the aftermarket antenna cable directly to the radio. If you remove the existing cable from the car antenna and touch the center conductor of the aftermarket antenna cable to the center conductor of the car cable does reception improve? If not then it may be a bad cable. If getting the car cable out is an issue, you could always route another cable.

If reception improves, it points to a problem with the antenna, most likely within the connector of the antenna.

I know on the C1 radios there is a trimmer capacitor that can be adjusted to better match the antenna / cable to the radio - turn for peak signal. Not sure if the C2 radios have this adjustment or not.

Tom

[J W.]

Re: 1967 coaxial cable help

I feel certain the issue is in the cable. I would like to know if anyone has removed the rear boot on the cable and found where the capacitor is located . Just looking for a possible fix before i start trying to remove or replace a cable. Trying to have car ready for Greenville regionals.

[Richard M.]

Re: 1967 coaxial cable help

On a C1 cable I had apart, the capacitors are soldered between the center conductors and the connector tip joints. One on each end iirc. I was able to measure them with a capacitance meter. I found they were ok but the solder was open on one end and I was able to resolder it. The caps are very small chip types.

I suspect the C2 cable is made in a similar way.

In your case, if replacement is planned, I would slice the foil insulation along the cable to remove it, then seal the foil back over flat and lay the new cable above it and under the carpet. The cable, along with the rear harness runs under the cover floor plate so the sill plate needs to come off also.

But one other thing you may want to check is to ensure your ground plane plate is properly connected via the strap connection points and the antenna base connection and antenna tip itself has clean contacts. The copper ground strap ends use toothed lock washers and may be corroded.

If undercar exhaust it will be more difficult to check but you'll need to get in there regardless to check.

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[Bob R.]

Re: 1967 coaxial cable help

If your only concern is to pass flight judging the radio has to work but volume and number of stations is not important just raise the antenna all the way up. My car passed with the same problem. I had an aftermarket cable on my 63 and had the same issue you are having. Poor signal strength and low volume. I found an original cable on eBay, installed it and the difference was incredible like night and day.

[J W.]

[Bob R.]

Re: 1967 coaxial cable help

In a PV (performance verification) test everything has to work exactly as it was designed so your radio would fail but in flight judging your radio will be checked during operations testing and it just has to turn on and off, work on am and fm and change stations. Strength of signal varies at different event locations and a weak radio station will pass judging. If you check the archives on this site you will find previous posts about the same problem and the repair is to replace the cable with a correct cable. Having the exhaust down is the best time to replace the cable as getting the new cable in with the exhaust in place is difficult.

[Harry S.]

Re: 1967 coaxial cable help

I had the same problem as Bob. I located an original antenna cable, plugged it into the radio and the other end into a spare antenna. Held the antenna in the air and the radio worked fine. That is when I removed the old cable and installed the replacement.

[J W.]

Re: 1967 coaxial cable help

FYI on antenna cable. when i removed exhaust to inspect cable i found the problem. the rubber boot on the cable was crimped too far up on the cable. The end of the cable was barely touching the pin in the housing. i removed the pinch clamp and pushed cable in housing and slid boot in place and re-crimped. thankfully radio reception is good. I'm sure that this after-market cable was assembled incorrectly and was installed by previous owner 17 years ago. Thanks for the responses.