Car antenna cable recommendation

[dbsoccer]

I am restoring a 1963 Chevrolet Impala. I need a cable for the radio (original radio is only AM). One brand of a reproduction antenna cable was made using 3c-2v cable which I learned was a cheaper type of coax. While AM is hardly glamorous I might upgrade the radio some day and besides I don't like the thought of using a poor quality part independent of radio. And I don't think the cost difference between good cable versus poor cable is huge given the length is roughly 15 feet.

Could someone recommend a type of coax this application?

Thank you.

 

[mmckenna]

I take it historical accuracy isn't a big concern? After all, it's going to be completely hidden...

3c2v was a cheap 75 ohm coaxial cable. There are lots of good 75ohm cables out there that are inexpensive and you can get them just about anywhere. RG-6 would be commonly used in cable TV, satellite TV, TV antenna type applications. You can buy simple extension cables at any hardware store for connecting a TV to a wall jack. Find a Cable TV installer, and they'll probably have piles of used stuff.
Slightly smaller cable would be RG-59. Used to be very common for TV antenna use, but most use RG-6 now.

For such a short run, you don't need anything fancy.

Bigger issue is the connectors. Often the radio end used what was called a "Motorola" connector. You can find those on Amazon:

Amazon.com: Pro Trucker Male Auto Motorola Style Antenna Plug Connector : Electronics

Amazon.com: Pro Trucker Male Auto Motorola Style Antenna Plug Connector : Electronics

www.amazon.com

The end that connects to the antenna would be a challenge.

 

[dbsoccer]

Thank you for the quick reply. I have a electronics store close by that I'm hoping will have what I need.
Historical accuracy is a concern when it is practical but what I've found is often it is not practical even if you're willing to pay a ton of money. An original cable would be 'old' dried out, dirty cracked, rusty, and probably broken if you can even find one. Most are after market and most likely cheap. An AM radio is not a big deal, obviously, but I would like it to sound as good a possible.

Thanks again.

 

[mmckenna]

Thank you for the quick reply. I have a electronics store close by that I'm hoping will have what I need.
Historical accuracy is a concern when it is practical but what I've found is often it is not practical even if you're willing to pay a ton of money. An original cable would be 'old' dried out, dirty cracked, rusty, and probably broken if you can even find one. Most are after market and most likely cheap. An AM radio is not a big deal, obviously, but I would like it to sound as good a possible.

Thanks again.

No problem.

Other than a the cable being slightly larger in diameter, no one will notice. There will be printing on the cable jacket with manufacturer/model/rating on it, but it'll be behind the dash and no one would ever see it. If it's a concern, it may wipe off with some alcohol and a rag.

For such a short run of cable, there will be no noticeable performance difference between RG-6, RG-59, RG-58 or the 3c2v.

 

[mc48]

https://www.autozone.com/p/metra-electronics-radio-antenna-extension-cable-ex144/220443?spps.s=4732&cmpid=PLA%3AUS%3AEN%3AAD%3AALO%3AGOO%3ATRS%3APMX%3AOTE%3AGEN%3ANA%3AALA%3ANA%3ANA%3ANA%3ANA%3ANA%3ANA%3ANA&gclsrc=aw.ds&gad_source=1&gad_campaignid=22142102098&gbraid=0AAAAADkcoVsrO344w0b-4O_ugeMXEy4Uf&gclid=EAIaIQobChMIwrH98_n8kgMV51z_AR1EBTPVEAQYAyABEgKJwPD_BwE&new_store_set=true

 

[RFI-EMI-GUY]

While the specifics of the cable elude me. I recall that for AM reception the cable capacitance was quite critical. There should be a trimmer cap, mica compression type, that tunes the antenna and cable to the radio. On some radios you could get to the trimmer under one of the volume or tuning knobs.

 

[dbsoccer]

Thanks mc48. The trick using this option would be finding the connector to fit the antenna. I may have a couple of places to get such a connect.

But for my education, and back to the cable differences, I did some research as I like to understand the reasons why and not just do whatever is recommended. What I learned was RG-6 is better suited for high frequencies where RG-59 is better for low frequencies. I recall they defined high and low as being above or below 50Mhz. AM radio frequencies are clearly in the low end (535Khz to 1700Khz) which would drive an RG-59 solution. But as I mentioned, I may want to upgrade to a little fancier radio that would have AM and FM. FM, of course is clearly in the high frequency side of 50Mhz. But I then wondered if the FM side of a AM/FM radio used the same antenna? I know of situations in my house where this not the case - as there is a separate FM antenna. But, on the flip side, I have a newer automobile that has an AM/FM radio and it has only one antenna - at least only one that is visible.

I was thinking about this before I got mmckenna's last response - independent of the cable selected "the difference would not be noticeable". I'm good with that but, again, this is an opportunity to learn about a topic where I have very little prior knowledge.

I may have a source for the cable to antenna connector. mmckenna gave me a link to the Motorola connector. And mc48 gave me a link to a cable that would need to be shortened and terminated with the cable-antenna connector. So I have a couple of options.

I really appreciate the help and the learnings.

 

[dbsoccer]

Ah....... RFI-EMI-GUY..... I believe you are correct. Thank you for the reminder. There is a small screw/trimmer under the volume control knob. And there is reference to this in the manuals. I suppose the process for using this feature is you tune the radio to a weak AM station and then tweak the trimmer to get the strongest signal?

 

[mmckenna]

Thanks mc48. The trick using this option would be finding the connector to fit the antenna. I may have a couple of places to get such a connect.

But for my education, and back to the cable differences, I did some research as I like to understand the reasons why and not just do whatever is recommended. What I learned was RG-6 is better suited for high frequencies where RG-59 is better for low frequencies. I recall they defined high and low as being above or below 50Mhz. AM radio frequencies are clearly in the low end (535Khz to 1700Khz) which would drive an RG-59 solution.

It's not that one is better for high frequencies and one is better for low.

It's that one is better for high frequencies and the other isn't quite as good at high frequencies. The difference is minimal, and that difference gets smaller and smaller on the lower frequencies. There will be no discernible difference between those two cables that your ears will be able to tell.

So get whatever you can find/feel like, and go with it. Coaxial cable losses at 540KHz receive are so small that it would take some high end lab grade test equipment to measure it. A 60 year old radio isn't going to know.

On AM Broadcast band:
10 feet of RG-6 will lose 0.446% of the signal between the antenna and the radio.
10 feet of RG-59 will lose 0.543% of the signal.

So, about 1 tenths of 1 percent difference. At that point, you buy what is within reach because your ears will never hear that 0.1%

But as I mentioned, I may want to upgrade to a little fancier radio that would have AM and FM. FM, of course is clearly in the high frequency side of 50Mhz. But I then wondered if the FM side of a AM/FM radio used the same antenna? I know of situations in my house where this not the case - as there is a separate FM antenna. But, on the flip side, I have a newer automobile that has an AM/FM radio and it has only one antenna - at least only one that is visible.

It's spitting hairs. The cable losses are also about cable length, and at less than 10 feet, it's such a tiny amount that you won't notice.

I was thinking about this before I got mmckenna's last response - independent of the cable selected "the difference would not be noticeable". I'm good with that but, again, this is an opportunity to learn about a topic where I have very little prior knowledge.

That's where the real value is.

 

[RFI-EMI-GUY]

Ah....... RFI-EMI-GUY..... I believe you are correct. Thank you for the reminder. There is a small screw/trimmer under the volume control knob. And there is reference to this in the manuals. I suppose the process for using this feature is you tune the radio to a weak AM station and then tweak the trimmer to get the strongest signal?

Yep. I think you do it near one end of the band. Probably any car radio service manual from the era should have similar instructions.

 

[RCBi-Dave]

I am restoring a 1963 Chevrolet Impala. I need a cable for the radio (original radio is only AM).

Hello and welcome dbsoccer. A 1963 Chevy Impala is a very nice car to restore.

The GM DELCO OEM antenna cable has an air dielectric center with spiral insulation, a very thin copper clad steel center conductor, and a braided copper shield with only an approximate 70% shield coverage.

When I worked on AM radio/antenna repairs for all GM brand vehicles, I used a 93-ohm coax cable instead known as RG62 to replace/upgrade the OEM antenna cables. The outer diameter was a very close match and the braided shield had way more braid density than the OEM antenna cables.

The RG62 coax cable was originally used for early IBM Local Area Networking. It was excellent to use for the long antenna cable runs made to the trunk area power antennas used by GM. It also did not require a retuning of the AM antenna system trimmer capacitor located inside the radio chassis.

Best Regards

 

[CollinsURG]

There is a 36 foot extension of 3c-2v on eBay. Because I looked at it, I got an offer of $15 free shipping. Qty 53 available

RV 3c-2v 75 ohm Coaxial Cable Male-to-Female Connect Cord 36Ft Long (NEW) Qty-1

Pardon Our Interruption...

 

[dbsoccer]

So in the meantime...... I took my antenna to a electronic sound/radio/stereo/speaker guru here in town and he felt he had a connector to fit the antenna. I then stopped by my local big box store and bought 20 feet of Southwire RG-6 quad shield coax. I'll order the Motorola connector mmckenna recommended and get this mini-project put to bed so to speak.

As it turns out, the big box store did not have the "per foot" SKU in their system so after 10 minutes of trying to figure out how to charge me they gave up and told me the cost for the coax was free.

Part of this is the opportunity to make my own cable. So much of this car project has followed the same path lots of research followed by the actual doing piece.

Thanks for everyone's help and enjoy the rest of the weekend!

 

[mmckenna]

Photos of the car would be a nice way to wrap up this thread. Just sayin'

 

[RCBi-Dave]

I then stopped by my local big box store and bought 20 feet of Southwire RG-6 quad shield coax.

Ok on trying your "FREE" 75-ohm impedance RG6 quad shield coax cable for the AM car radio.

The OEM GM DELCO radio air dielectric coax cable has an impedance of approximately 100-125 ohms with an extremely low capacitance pF per foot. The RG6 coax has a much higher capacitance pF per foot so you will need to adjust the AM antenna system trimmer capacitor located inside the radio chassis. Select a known low to medium signal strength AM radio station in the middle of the band and tune for the loudest audio output.

I have found that the extra capacitance per foot from the 75-ohm coax disrupted the internal antenna matching circuit too much and could not be adjusted for good AM radio performance.

I clearly remember that I had backed off the internal trimmer capacitior so much on one car with a Delco Wonderbar radio that the adjustment screw and associated layered mica insulators fell out. A definite P.I.T.A. moment. The time consuming removal, reinstallion, and repair of that radio in a 62 Corvette made a permanent memory since I was expecting a simple plug-n-play event with the car owner watching. I ended up replacing the RG59 75-ohm coax with RG62 93-ohm coax, and after retuning the trimmer capacitor very carefully again, everything worked fine on AM.

I only had good luck using the TV type RG59 or RG6 coax cables for the FM portion of car radios since they have a 75 ohm input impedance for their receiver antenna circuit.

FYI, FORD OEM actually used antenna coax cable with the RG62 markings.

Yes, I agree with mmckenna. Please include photos of your 63 Chevy Impala.

Best Regards

 

[dbsoccer]

RCBi-Dave Since my goal, at least initially, is to have just the AM ratio your comments and experience seems to push me away from my free RG-6 cable. So now I need to find a source of RG62 cable in something less than a 1000 foot spool.

I found a place on the Newark site that lists at least 15 different flavors of RG62. https://www.newark.com/c/rf-wireles...emblies/coaxial-cable?coaxial-cable-type=rg62

McMaster-Carr has a 25ft piece for RG-62A/U $62 but I'm hoping I can find something more reasonable as M-C is always pretty pricey. McMaster-Carr

Below are a couple of pictures. It start with the body coming off the frame. Frame was powder coated and everything that was added back was new, refurbished, powered coated, painted, etc. All new wiring. Basic 327 rebuilt, 3-speed rebuilt, differential rebuilt, etc. I had a local shop do the paint. Because of the color they had to paint it all together so they put the fenders and hood on loosely. But I brought it home without the fenders so I could finish the firewall without hanging over the fenders. I'm doing the wiring and windows now. I may fit up the radiator and start the motor for the first time. Eventually I'll take it back to the body shop and they'll put the fenders and hood on. The trim will be last and possibly one of the more expensive steps as the refurb on trim is costly. And I may be missing some pieces (yuck). I originally bought the car in a partial state of dis-assembly so there have been some challenges in this area but fortunately there are many people online who have lots of experience and parts are available (for a price).

 

[KJ4DHF]

https://www.pasternack.com/flexible-0.242-rg62-93-ohm-coax-cable-pvc-jacket-rg62a-u-bulk-p.aspx

 

[dbsoccer]

$6.29 per foot versus the $0.37 per foot for the RG-6. Wow!
M-C was less.

I am hoping a local radio store may have something.

Thanks!

 

[mmckenna]

$6.29 per foot versus the $0.37 per foot for the RG-6. Wow!
M-C was less.

I am hoping a local radio store may have something.

Thanks!

It will be difficult to find locally. RG-62 was used for old coax based data networks and some car radio applications. A radio shop won't stock something like that. It's going to be something you'll have to track down and order. E bay has some if you search on RG-62. Still not cheap, but cheaper….

 

[dbsoccer]

Someone on Ebay has new Belden R62 B/U. It appears the core wire is braided as opposed to solid.
Concerns? Thoughts?