Anyone repair stock antenna cable?

[ATW]

The connector for the back of the radio pulled off the antenna cable. I cut the cable back a little hoping to find the "coax but there is just a plastic shield inside with 1 tiny strand of wire running in it. Can this be fixed or retrofitted with a more modern cable? This is for a 67 Dart with factory telescoping antenna. I'm not against using another route for an antenna.. just want the FM radio for my Sony in-dash head unit.

 

[67Dart273]

The reason that feedline is built like that is that it is VERY high impedance. This "gets into" deep theory even I've forgotten but the short answer is, an AM antenna "quarter wave" which would equate to a 9' "quarter wave" whip for say, CB radio, for AM would be not 9 ft, but HUNDREDS of feet. (550khz would be some odd 425 ft tall!!)

This causes the feed impedance of such a short antenna to be "off the map." In other words, they are not efficient

If you were to replace this with something more common, such as 52 ohm CB/ two way coax which is 50 ohms, or TV coax which is 70-75 some ohms, it would severely attenuate the AM signal

 

[67Dart273]

You might be able to repair it if you are careful. Carefully strip it back, heat the connector center pin and "knock" it straight down on your knee, etc, to shake the solder out and clear the pin. I forget.......I think the braid end is crimped. Been years since I've fiddled with one

 

[dirty white boy]

The reason that feedline is built like that is that it is VERY high impedance. This "gets into" deep theory even I've forgotten but the short answer is, an AM antenna "quarter wave" which would equate to a 9' "quarter wave" whip for say, CB radio, for AM would be not 9 ft, but HUNDREDS of feet. (550khz would be some odd 425 ft tall!!)

This causes the feed impedance of such a short antenna to be "off the map." In other words, they are not efficient

If you were to replace this with something more common, such as 52 ohm CB/ two way coax which is 50 ohms, or TV coax which is 70-75 some ohms, it would severely attenuate the AM signal

making me think of the days long ago when i was into hotrod cb's and all sorts of trashy trucker things! coax cable rules,..3 foot intervals 3,6,9,12,15 foot lengths,...dont neatly roll up extra, itll have bad affects! the airal length is ratio'ed to coax to get proper swr's,....2 whips more dominant than 1 but 1 get out and pick up farther!,...a slight reverb will alter your output waves and they'll travel farther quicker, heavy reverb wont matter how it gets out no body be able to under stand a word you modulate!! ant thought bout none that since i gave up being a high speed chicken hauler...lol op can get new coax end at radio shack or on fleybay be easier than cleaning factory soldr outta the old one,..coax has black rubber insulation with braided ground wire mesh that gose to outter potion of plug, then theres the hard white inner plastic insulation and the single wire to center pin is inside that...not to bad but can be tricky,..solder gun skills needed but doabile...

 

[67Dart273]

making me think of the days long ago when i was into hotrod cb's and all sorts of trashy trucker things! coax cable rules,..3 foot intervals 3,6,9,12,15 foot lengths,...dont neatly roll up extra, itll have bad affects! the airal length is ratio'ed to coax to get proper swr's,....

Unless you are talking about a phasing harness for two antennas, "trimming coax" IS NOT how you get the swr down. In fact, all it does is full your meter. The fact is SWR is generated by mismatch between the ANTENNA, and the coax and radio. The only way to get swr truly flat is to make the antenna itself flat

Let's say you had ?? feet, maybe 20 feed of feedling, with a mismatch. Let's say you had a connector every foot--foot an a half. You would find that as you move your SWR meter to each connector, THE READING WILL CHANGE. Does this mean the SWR changes? No, the different readings are generated entirely by the mismatch condition itself

To put this more simply, if you had a TRULY matched antenna system, that is, "flat," you could move the meter ANYWHERE along that coax and it would read the same

In other words, trimming coax is a crutch.

There are two conditions in systems of these types:

1...The antenna can be RESONANT, but this does not mean the SWR is flat. This is because the impedance of a resonant antenna is NOT necessarily 50 ohms!!!

2....Therefore once the antenna is resonant, the impedance must be matched to the coax AT THE BASE OF THE ANTENNA by means of inductance/ capacitanc (LC) network of some type.

This is the ONLY correct way to set up an antenna system.

I used to use a "screwdriver" antenna from 160M through 10M, Metron 1KW amplifier.........all legal on amateur radio

................similar to this photo off the net

These, in their original form, and where they got this name, is that they used an old B&D rechargeable screwdriver motor to run the coil in and out of the housing. The large white object is the add on 160M coil, the small white object is a matching network goes onto the base -to- coax connection

"Long before" distracted driving was such an issue (and traffic was a little lighter LOL) I had tape markers on the housing for the band markers. I could tune the thing and change bands while driving.

Worked all over the world, Australia, Japan, England, Germany, Spain, and the Soviet. A few others I've forgotten, and one morning, the Orkney Islands

 

[moparmat2000]

I used to be able to buy repair ends for the old antenna wires. There was a little set screw that tightened down on the single plastic shielded inner strand. Radio shack had these i think. Male end motorola connector.

 

[KitCarlson]

Before you fix the plug, it might be worthwhile to make three tests with Ohm meter. The outer cable shield should measure low Ohms to car body ground when antenna is installed. The inner cable wire should measure low resistance to antenna. The last test is measure outer shield to inner wire, it should be very high resistance.

 

[dirty white boy]

Unless you are talking about a phasing harness for two antennas, "trimming coax" IS NOT how you get the swr down. In fact, all it does is full your meter. The fact is SWR is generated by mismatch between the ANTENNA, and the coax and radio. The only way to get swr truly flat is to make the antenna itself flat

Let's say you had ?? feet, maybe 20 feed of feedling, with a mismatch. Let's say you had a connector every foot--foot an a half. You would find that as you move your SWR meter to each connector, THE READING WILL CHANGE. Does this mean the SWR changes? No, the different readings are generated entirely by the mismatch condition itself

To put this more simply, if you had a TRULY matched antenna system, that is, "flat," you could move the meter ANYWHERE along that coax and it would read the same

In other words, trimming coax is a crutch.

There are two conditions in systems of these types:

1...The antenna can be RESONANT, but this does not mean the SWR is flat. This is because the impedance of a resonant antenna is NOT necessarily 50 ohms!!!

2....Therefore once the antenna is resonant, the impedance must be matched to the coax AT THE BASE OF THE ANTENNA by means of inductance/ capacitanc (LC) network of some type.

This is the ONLY correct way to set up an antenna system.

I used to use a "screwdriver" antenna from 160M through 10M, Metron 1KW amplifier.........all legal on amateur radio

................similar to this photo off the net

View attachment 1715053144

These, in their original form, and where they got this name, is that they used an old B&D rechargeable screwdriver motor to run the coil in and out of the housing. The large white object is the add on 160M coil, the small white object is a matching network goes onto the base -to- coax connection

"Long before" distracted driving was such an issue (and traffic was a little lighter LOL) I had tape markers on the housing for the band markers. I could tune the thing and change bands while driving.

Worked all over the world, Australia, Japan, England, Germany, Spain, and the Soviet. A few others I've forgotten, and one morning, the Orkney Islands

you feffently know lot more than i ever did,..cb shop use to take whip off my wilson 2000 antinna and cut a 1/8 inch off to fix swr's was told to match the coax really dont know much my self
but spent bunch of money asked lots of questions and tryed to learn! in trucking world theres more myths to cb's than truths...

 

[ATW]

I stopped and bought a $11 aftermarket Metra antenna and fabbed up my own bracket to use it with the 67 factory bezel. Calling this project complete.