CB antennas and coax

[Midnight Flyer]

I've noticed while reading Truck Paper that a lot of trucks listed for sale include a factory installed CB radio. Most likely they include a bottom-of-the-barrel antenna and coax. If I was gonna buy a CB radio I'd most likely opt for a Cobra 29. But what's a good antenna for a big truck and is one coax just as good as the other? :?

[Uturn2001]

There are a lot of good antennas on the market. you have those from well known makers such as K-40, Francis, and Wilson. Then there are some more "custom made" types.

And no. Not all coax is made a like. Good coax will have plenty of insulation for low signal loss and there are several different types of coax. Basic RG 59 and RG 59 coax is about the worst there is for coax. You get a little better if you can find those with the "foam" insulation.

For general mobile installation though RG 8x also called Mini 8 coax is pretty decent and has a lower loss than any of the 58 or 59 coax.

[JeffTheTerrible]

Any halfway decent CB shop can set you up with a good antenna, but they'll often try to sell you more than what you actually need. If I were running just a no frills, no gimmicks CB radio, the most expensive antenna I would be willing to buy would be the Wilson 1000, if I even felt like spending that much. As it were, I bought mine for $30 from some guy loitering around one of the terminals for the company I was working for, and it was brand new in the package, so I bought it, and chose simply not to ask any questions.
As for coax, I typically go with Belden coax, cut and set up by a CB shop, rather than the stuff you see sitting on the shelves of the truck stops from Barjan or whatever the hell the brand is which sells that stuff.

[Blind Driver]

My antenna is nothing more then a simple Firestick. I normally get a 11 mile range with my Uniden.

Also, does the length of the coax make a difference?

[hatt91]

Coax are NOT all the same. I agree Belden is a very good brand. I'd stay away from the stuff they sell at truckstops. If you are running just 1 antenna remember to go with 50ohm RG-8 or RG-58. The RG-59 is 75ohm and is for running 2 antennas.

The antenna is the most important part of the system. A good antenna with a crappy radio will sound better, in general, than a good radio with a bad antenna.

That being said, I have tried K40, wilson, firestick and some truck stop POS, and i would recommend the wilson hands down. Definatly a noticeable difference in recieve.

As for the length, some people swear that the coax needs to be 18 ft long, because that is 1/2 the wavelengh of the CB band (11 meters). If you can't afford that, I don't think there would be a problem going with a shorter length, I would suggest going with a length that is maybe 9 or 6 feet just to get some sort of even fraction for the wavelegth. Also, if you have any extra slack, do NOT coil it up nicely. The creates a RF choke and severely limits your radio. Just let it go randomly loose.

[geeshock]

I'd definitely recommend the mini 8 18ft coax. I switched my coax and heard a world of difference. Also, I used to have a skipjack antenna and it did very well and cost me all of $30. I now have a 10k competition and am doing realy well but thats a $85 antenna.

[Mackman]

is this good for a single antenna setup. My mack came with 2 antennas on the truck i just un-hooked one of them cuz i hear 1 works better then 2. But all the coax are still there for a dual set-up.
http://www.gijoesradioelectronics.co...?idproduct=914

[belpre122]

is this good for a single antenna setup. My mack came with 2 antennas on the truck i just un-hooked one of them cuz i hear 1 works better then 2. But all the coax are still there for a dual set-up.
http://www.gijoesradioelectronics.co...?idproduct=914

Mini-8 may have more loss than RG-58 at 27MHZ, I'm not sure. But at a 9-18 foot coaxial run at that frequency, the loss would be negligible.

I would go with the 18 ft length as opposed to 9 ft. 18ft is approximately the length of one full wave at 27MHZ, as 9ft is approx. a 1/2 wavelength.
The 18 & 9 foot coaxial advice is based on sound theory. A full wave (18ft coax run) will exhibit a higher db gain at (full wave configuration) as opposed to the totally acceptable, but less efficient, 9ft (half wave config).

Also, if you have any extra slack, do NOT coil it up nicely. The creates a RF choke and severely limits your radio. Just let it go randomly loose.

Great advice Hatt!

Like Hatt91 said, the antenna is the most important part of the set up. Proper coaxial setup is so critical, to include minimum VSWR.

With all of this great advice, the Mackman BBR ought to be able to broadcast redneck rock-box chatter all over the Keystone State!!

[Mackman]

can someone put up a link of the best coax money can buy

[HWD]

can someone put up a link of the best coax money can buy

The "best coax money can buy" is hardline 1" diameter or over...good luck running that in your truck. RG-8U is hard to deal with in a mobile setup and totally unnecessary, too. If you want a simple to install yet top-of-the-line antenna/coax setup, get a Wilson 1000 trucker and some Times Microwave LMR-300 (Times part number 40297) and you will have pretty much the best you're gonna get. That coax is low-loss RG-8X with a solid center conductor and 100% shielding. Also, big gaudy open coil antennas are for show and net you no improvement performance over a Wilson.

Contrary to CB myth, the length of the coax does NOT matter if you are using only one antenna. If your SWR changes with changes in coax length, you have a crap antenna or a ground problem. The only time coax length matters is in properly phased antenna systems with more than one active antenna element. And since you can not get the proper antenna spacing for a correctly phased system across a semi-tractor, you would be better off with one antenna.

[DaveP]

Scroll way down past illustration.3 and you'll find coax lenght explained.

http://www.signalengineering.com/ult...ax_basics.html

[matcat]

I've used RG6 with no problems

[kc0iv]

I've used RG6 with no problems

Why would you use RG-6/U coax? RG-6/U is a 72 ohm coax. It also has a solid center conductor.

kc0iv

[countryhorseman]

I think we are talking CB installations here, not satellite tv!

I've used RG6 with no problems

[countryhorseman]

Some things to consider in antenna installation!

1) The antenna should be selected as such, so it can be mounted in a vertical or near vertical positions! Not anteater style laying down at 45 degrees!

2) Antenna design - coil position!
Of all the designs suggested and available, all the coil positions have been discussed!

a) Base Loaded - not practical in most truck applications, since it is near impossible to locate the coil above the roof line of the truck!

b) Mid-Coil - i.e. Wilson Trucker style, to be effective, 75% of the coil needs to be above the roofline, or in the case of fiberglass trucks, above the structural steel portion of the cab.

c) Top-coil - i.e. Firestick, Cobra, Francis or K40 Fiberglass whips - by all practicality, the best for most trucks and mirror mounted configurations! As the coil is at the top of the antenna and easiest to mount in an optimal configuration. Can also be purchased from 3 foot to 5 foot lengths, and most are easily tunable!

3) How many antenna, well, that depends on personal preference, availability of mounting locations, budget, and need to get out and touch someone!

a) Single antenna - the easiest and most economical to mount and set-up, and in most cases will yield good range results. RG-58 or Mini8) are exceptable in these situations, other types are stiffer and harder to use in a mobile set-up. Depending on the mounting location and grounding of the mount, will yield fair to optimal radiation patterns (i.e. front, back and side-to-side). Some trucks, such as Columbia's and Century Class will need a 12 guage or so wire run to the frame or other chassis ground, since the doors on these trucks do not yield good grounding through the mirror mounts.

b) Dual (co-phased) - little harder to properly set-up and match, also more expense. But in a tuned (i.e. boosted) radio, will yield much greater results, usually front to rear, side-to-side suffers a bit, but we need front and back more! Matched (co-phased) RG-59 is needed in this set-up for best SWR and lowest loss! (at least in a mobile set-up). Another note of interest - Properly set-up Dual (co-phased) antenna do not need a grounded mount. Thus, they work quite well in set-ups such as the T-2000 and Pete 387's. Although, grounded mounts do not hurt, and in some cases will extend the range and directional ability of the set-up.

c) Also, the best case scenario is the antenna be mounted 8 to 8'6" apart, any closer and they will need more playing around with to get a good SWR match, and a change in coax will be needed! I have mounted as close as 6', but needed to use RG-58 and a custom cophase connection! This set-up was very directional and not practical for daily trucking use!


Firestick has an excellent tutorial on their website, as well as other sources!

Safety! If you plan to push some amps! Get the coil away from you! Many do not realize the RF (radio frequency) burns! A high power linear pushing through a base or mid-loaded coil in close proximity to your arm or brain ( :?: ) can burn you and/or increase the risk or cancer! A friend of mine, had been driving for 20 plus years, loved his linear's, and quite often ran them cranked up! His custom antenna, much the same as the monkey-made and similar was mounted less than three feet from his head! He constantly had burns, similar to a sun-burn on his arms and forehead, also lost much of his hair! This man wore a cowboy hat at all times, except when in bed or in church, so the burns to his forehead were unexplained, until after his death!

He passed away 3 years ago from brain cancer, also had skin cancer on his left arm! After some research, and speculation, it was determined the cause of the cancer was his radio and linear!

You do not have to believe this story, since there are many articles and papers on the effect of high power RF to the body. A microwave oven is a RF generator - that is how it cooks food! Read the papers yourself! Part of the testing for an Amateur License is related to RF safety!

Anyhow, just supplying information, and not wanting to start the usual wars that occur regarding radios on this forum!

Good luck setting your rig up!

Another note: If you do not own an SWR/Power meter, get one! Not the $19.95 variety sold at the truck stop! You do not need a Bird! Radio Shack sells a good one for casual use, as well as some other outfits! Have noticed lately that the Pilot is carrying one, around $49, that looks very similar to the RS unit! Use it to match your antenna to your radio, and then occasionally, every other month or so (do not leave it connect full time), or if you notice a deterioration of your signal! Coax no matter how good it is, does break down over time. Antenna mounts may generate corrosion, thus loosing grounding or the little nylon washer between the antenna and the base mount will deteriorate and ground out the whip, causing your SWR's to go through the roof! Older trucks with worn door and corroded door hinges are also culprits of fluctuating readings!

[matcat]

I've used RG6 with no problems

Why would you use RG-6/U coax? RG-6/U is a 72 ohm coax. It also has a solid center conductor.

kc0iv

Never used it for mobile use, but for base station with 1600w linear it works quite well.

[kc0iv]

I've used RG6 with no problems

Why would you use RG-6/U coax? RG-6/U is a 72 ohm coax. It also has a solid center conductor.

kc0iv

Never used it for mobile use, but for base station with 1600w linear it works quite well.

Still don't understand why you would use 72 ohm coax for CB unless you are feeding a 1/2 dipole? Even then pretty hard to find balun for 72 ohm coax. Let alone finding connectors that will connect to the linear.

If you are using a rotating beam then solid core sure isn't going to last very long.

kc0iv

[heavyhaulerss]

For all c.b/ antenna related questions you can find all u need at cbradiotalk.com