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post #1 of (permalink) Old 02-18-2007, 03:07 PM Thread Starter
 
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C.B. radio antennas

Who has hot tips on what kind of CB mounts to use on the Wrangler, and what brand of CB antenna works best? Wilson? Firestick? Anyone have experience with the behind the rear light mount offered by Quadratec?
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post #2 of (permalink) Old 02-18-2007, 03:24 PM
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Re: C.B. radio antennas

I like my spot on the bumpstop for the spartire. I have a firstick works well but I want a Wilson. if you ask me there the best. I have 5000 on my truck and i get out very well. I work skip all the time... If you get a firestick get a good spring for it or you will snap that thing off in the trails..
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post #3 of (permalink) Old 02-18-2007, 03:29 PM
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Re: C.B. radio antennas

Antenna is part of it a bigger part is radio, ground, using an external speaker and tuning of radio and antenna. My suggestion regaurdless of what type of antenna you use have a professional shop hook up and set up everything. Your clairity and range will generally be much better. On my Jeep I have a steel 102 inch from radio shack connected to the rear bumbper on my semi on run cobra brand fiberglass tunable 48 inch. Both my radios have been peaked and tuned as well as my antennas have all been tuned a good mic helps too.
John
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post #4 of (permalink) Old 02-19-2007, 12:12 AM
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Re: C.B. radio antennas

What Babypoo says is correct....if you have the bucks, pays someone to set it up if your electrical skills are of the newbie skill.

But to add to the confusion....a few points of interest....

Antenna are designed by wavelength. The wavelength is the distance the signal travels in one cycle....for the CB frequency range, this would be around 39'....as you can see, that would be kinda long for an antenna...hence, most antenna are in fractions of a wavelength with 1/4 being the most common. This would mean a 10' antenna.

As most of us know, a 10' antenna is still too long...that is where we get into fully loaded, top loaded, bottom loaded and middle loaded antenna. Basically, a coil of wire is added to the antenna to make the CB 'think' the length is longer than it is. It keeps the impedance correct but the effective propagation are...or in other words...effeciency...

I think the best type is the fully loaded....you can recognize it by the wire that is wound around the shaft (typically fiberglass).

Next is the propagation pattern. As noted above, the jeep body plays a very important part of the ground plane for the CB. The best analogy I can give is comparing it to jumping into the water...if you do it from a small boat, you don't get much distance because the boat pushes away from you...but if you do it from land, you can jump further. Where you place the antenna dictates the pattern. If you put it on the right rear corner, then a majority of the energy is projected in a direction from the antenna towards the left front. Basically, the propagation pattern looks like an long oval. If you place the antenna on the roof of the jeep, the pattern takes on a more round shape.

One point (and we will most likely hear exceptions to this)...the length of the coax from the CB to the antenna does not make a significant effect on the SWR (Standing Wave Ratio)

SWR...the effective length of the antenna and the frequency being used determines this. In a perfect world, if the length of the antenna is exactly a multiple of the wavelength (1/4, 1/2, etc), then all energy is being sent to the antenna and there is no reflected waves...which is a ratio of 1:1. Change the length of the antenna and the SWR starts going up (too complicated to explain here). Hence, when you tune the antenna it needs to be done on the middle freq (chan 20). Yes, this means your SWR goes up at chan 1 and 40. Not much you can do about it unless you have a variable antenna.

So....have I confused you enough? And I didn't even talk about characteristic impedance, mw or watts.
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post #5 of (permalink) Old 02-19-2007, 06:14 AM
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Re: C.B. radio antennas

Yeah...what they said.

I have a 4' Firestick (adjustable) on the spare tire bumper. I don't have my spare on the tailgate any more and I keep bashing that corner into big 'ol rocks...so the mount has to move somewhere else. The Firestick has worked well, but, having the radio "tuned" (not just the SWR) helped a whole bunch.
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post #6 of (permalink) Old 02-19-2007, 09:40 AM Thread Starter
 
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Re: C.B. radio antennas

Good insights - thanks all!

Babypoo - do you have an auxillary ground strap going from your whip to the tub? Or is the grounding through the bumper and its related mounts to the frame sufficient for you?

I have a Wilson 5000 base-load on my company car and I run barefoot; I can easily reach 7-8 miles on normal days (no sunspots) so I agree that Wilson's probably the way to go. But I ran a whip many many years ago on a pickup I had and had forgotten about that option until babypoo mentioned it. And I think the bumper mounts with a spring should withstand most trail abuse. Getting the rig into the garage is another matter though! I'll have to strap down the tip when I'm not using it.

I haven't had the radio tuned yet - it's still in the box, a lower-end Cobra with weather bands. But for trail work I think it'll be adequate. I may get it tuned eventually - need to check SWRs whenever I finally figure out which antenna to install, and then get around to doing it -

Thanks again, y'all!
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post #7 of (permalink) Old 02-19-2007, 10:43 AM
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Re: C.B. radio antennas

For years I used a fairly rigid fiberglass 1/4-wave whip with a tuneable 2-foot tip - Shakespear, I think. I was afraid of breaking it but it always held up. The main problem with it was that it wouldn't fit through the garage door, so I went to a stainless steel single-piece 1/4-wave. It was quite tough and flexible, and never caused any problem.

I don't know how antenna technology has progressed in recent years, but the "common knowledge" used to be that as antennas became physically shorter, they also became more critical about tuning length, and also more sharply tuned - their efficency dropped off more quickly when operated off of their optimum tuned frequency. In other words, one might be 95% as efficient as a 1/4-wave on channel 20, but only 80% as efficient on channel 4.
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post #8 of (permalink) Old 02-19-2007, 11:35 AM
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Re: C.B. radio antennas

The longer the antenna is the better for receiving - but --

Most clubs and 4x4 associations ban the long steel whips for good reason. Bystanders along the trail are in danger of getting "whipped" or losing an eye. Most clubs limit the length to 3 feet or so.
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post #9 of (permalink) Old 02-19-2007, 11:45 AM
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Re: C.B. radio antennas

[ QUOTE ]
Most clubs limit the length to 3 feet or so.

[/ QUOTE ]

Interesting! At the Badlands O.R.P they mandate a whippy, six-foot fiberglass pole with a marker flag, for visibility over hills. [img]/ubbthreads/images/graemlins/headspin.gif[/img] [img]/ubbthreads/images/graemlins/thud.gif[/img] [img]/ubbthreads/images/graemlins/lame.jpg[/img]
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post #10 of (permalink) Old 02-19-2007, 11:50 AM
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Re: C.B. radio antennas

The fiberglass poles are not as "whippey" as the 12 ft metal whips that are used as killer CB antennas.
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