Coax length
 

Mounting an antenna on the spare tire bracket, (where you are not supposed to) then going along up to the front, thinking about above the rear view mirror, how short of coax can I get away with, without it pulling tight, 2018 jk 2 dr
looking at a president mickinley ssb cb.
It is recommended less than 13 ft

What you want is the shortest possible length of coax to reach the best possible location (one with a good ground plane, which is next to impossible on a Jeep). I'd ignore the "less than 13 ft" recommendation and just do the best you can. Keep in mind that, on a Jeep the antenna location--specifically the best possible ground plane--is going to be more critical than the length of coax to best radio performance. A foot or three extra coax just isn't going to make that much difference. And, if you run across anything that says you need a specific length (usually 18 feet for CB), ignore that, too. Some folks and one antenna manufacturer have confused considerations for installation of phased array antennas with installation of single antennas.

My background? I spent nearly a quarter century maintaining and flying (as a crewmember) the EC-130E Airborne Battlefield Command and Control Center aircraft. During that time I was one of the lead government representatives with Lockheed Martin on the upgraded installation of the 30 HF, UHF, VHF, FM and SATCOM radios. Never at any time did anyone ever ask, "Is that coax the proper length?"

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Great post Mark :2thumbs:

Thanks, one less thing to worry about

Yes, what Mark said !

PS. Mark, for a moment I thought you traded in your Jeep for that 130 :)

C-130s are my former ride. ;-)

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That's me, front and center ...

What an awesome photo (not to mention the amazing memories you must have). A brother of mine was an Airborne Ranger and had a few stories to tell about the C-130. It must be something to be aboard one.

PS. I had a bad one liner about using 17' of rg-58 to the CB in the cockpit but I think I should just let the bad humor pass. ;)

That fellow I have my arm around is an Army Ranger. Our job was to get air support to the Army. He was a liaison, permanently assigned to the squadron. This was after the first combat flight of a JTIDS data link system, which delivered a lot of data to the battlestaff--AWACS radar picture, etc. Mission had been flown out of Italy over Bosnia, back in the very early days of that conflict (supporting U.N., before NATO became officially involved).

My brother was in traffic control in the Air Force,
33rd combat communications, then before he retired he was the tower chief at Tinker AFB, I don't think he knew much about how it all worked, but he talked on the radio a lot

I used an 18 ft coax cable on mine. Has enough of a loop between the tailgate and rear of the roll bar to open the tailgate. Not much extra left over. Works fine.

Woops, that's for my 4 door, I see you have a 2 door so you won't need as much.

I've used 3 setups. First one was with Arizona Rocky Roads mounts, sticking above the stock tire carrier so the antennas are above the spare tire. Ham on one side, CB on the other, and although they should be separated more both worked at the same time. I currently use a front fender mount bolted to the fender for my ham, could be used for a CB, it works well. I currently use my aftermarket spare tire carrier mount for both a cb and ham, again raising it above the spare, but I only use either the ham or CB at that location. If I use the ham and the CB, the ham uses the front fender and the CB uses the rear tire carrier. Works fine.

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By the way, I did run a ground wire from the tire carrier through the tailgate to a stock small screw on the floor next to the rear speaker. The worst SWR is on the aftermarket tire carrier, but it works. The best SWR I've ever had is with a simple mag mount antenna sitting on the hood!

You definitely need sufficient relief for movement. It's worth mentioning, however, that if there is excess cable in the transmission line, don't loop it up and hide it under the carpet. That loop can cause SWR issues. That's one reason I'm not a fan of the pre-cut cable/connector packages. The other reason is that sometimes those packages have very poor grade RF cable--I've seen them with as little as 15-20% shielding coverage. I recommend buy a high grade cable and high grade connectors, include a few extra feet for mistakes and mis-measurement, run it, including strain relief where needed, and then cut off, leaving a couple extra inches at each end for future repairs. Any exterior connections should be sealed up with RTV to prevent water intrusion.

Yep. The wonders of having a decent ground plane.

"Best" for performance is as previously mentioned: Smack dab in the middle of the hood. You'll have a great ground plane. And the cops perhaps taking an interest in you. So probably not very practical. Especially if you travel through heavy brush. I have friends who've installed on the front bumper (aftermarket steel) with great success. And if you're not worried about brush or the antenna being in the way of your photo shoots (which is why mine isn't there), that's a good place. Pretty easy to wire up, too. I did have my 2m/75cm ham antenna back on a AZ Rocky Roads mount, but it wasn't performing very well. Moved it up to the overhead rack and it does much better. Bear in mind that a ground plane does not need to be a solid sheet of metal. Depending on the wavelength at which the radio is operating, screens, individual elements of metal tubing, etc, can all provide an effective ground plane. My CB I've kept on the tailgate. It's range is limited because of that, but it works for trail use, and roughly a mile or so along the open highways. Primary reason I leave it there is for protection from brush. It still gets banged around some, but I've never had it broken off. Have had to replace because the banging around damaged it internally. I carry a spare, as well as a spare (handheld) radio.

Might be of interest--some heavy brush starting at 8:00 ...

Will this work?

https://www.aliexpress.com/item/UHF-...731773332.html

Another option is a fellow who lives on the other side of OKC from me. Ham operator, he carries quite a few types of cable and connector. Super nice fellow. Might give him a call ...

https://www.coaxman.com/

Funny you ask about the trailer. The guy pulling the trailer and the fellow driving the pick-up took the more open road down to the campsite we were headed to. Trailer puller didn't want to scratch up his rig, and truck driver had driven the route we were on only two weeks prior and didn't want to go through "The Jungle" a second time. And, though that wasn't a Conqueror, after this trip that fellow sold that trailer and bought a Conqueror, which is what he has now. His Jeep, BTW, had a Hemi. In fact, at the time he had two Hemi Jeeps, but now he also drives a pickup. I think he has a Colorado.

The fire stick coax I ordered is 18', one end has the "fire ring" the other is just coax with a solder on terminal
Would cutting the coax at what ever length it takes to get from the antenna to the radio cause any swr trouble, or is it better to keep it at the 18'
I know 18 is 1/2 wavelength, the antenna is 5/8, but the coax is "shielded" so isn't it more or less just a way to connect the radio and antenna

If I understand that correctly, you just need the correct reducer adapter ...

https://www.americanradiosupply.com/...YaAnpnEALw_wcB

To be certain, you have RG-58 or some other 52 ohm coax, correct? I've found 72 ohm coax surprisingly easy to get since that's what many cable TV systems have used for years. But you wouldn't want to use that for a typical Jeep install.

Coax length
 

Well, you need to take into consideration the frequency (wave length) you plan to use. If you're using HF, you have wavelengths in metres but once you go UHF and beyond you are now talking centimetres /millimetres. This means that cable is now many multiple wavelengths long and it's then cable losses become significant. As an example, UHF CB is around 62cm, so a metre of cable is already two wavelengths long.. Cables have specs that will tell you the losses to expect.. The quality of your attachment is also significant, crimped inner conductor and a few scraggly strands of the shield (outer) will not help to get all that power to the antenna... But that said, only a couple of Watts of radiated power will suffice on the tracks to chat with your mates or the spotter who makes sure you don't drop your wheel down that deep wash-out 😉

The center of the hood is best location

@Mark Doiron sorry for the really late reply. I scored a whole bunch of this off the Duncan avionics guys. I still have about 15’ left over. This isn’t the exact part number.
https://www.picwire.com/pic-cables/r...onnector-list/
I had no issues getting that 90 degree fitting on the cable or the straight PL259. I did have to really crank the straight connector on though. My setup works okay. I thought I’d be inventive and make a .032’ aluminum ground plane for it and installed it inside my license plate plastic. Not happy with it thinking I am going to just go ahead and move it to my steel rear bumper and be done.

I also really need to tune in my antenna properly with the SWR meter. I was being lazy because I did not want to pull the radio back out and hook up the meter. I tried adjusting the SWR as best I could hooked near the antenna. I had to splice in some length on my coax, due to not being happy at all with the Rugged Ridge tire mount bracket.

Set up works fine when on the trail with buddies, but trying to keep in touch with people at the bottom of the trail when I am up top, not so much.

I am using a Cobra 29 LTD mounted under the rear view mirror, on top of the dash. I have a 17' coax running to a grounded metal plate on my roof, just above the fuel door. The coax is run over the roll cage out the back glass, to a magnetic Wilson antenna. With the cheaper radios, I was getting a pulse of static about every second, but the new radio eliminated that. I realize that the center of the hood would have been the best spot for the antenna, but I am running a 10th anniversary hood, on my 2013 Rubicon, and there are really no flat surfaces. Hope this helps someone......Mike