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-   -   Cant get a low SWR with my CB (http://www.wranglerforum.com/f40/cant-get-a-low-swr-with-my-cb-236173.html)

Giantxtc 04-18-2013 04:44 PM

Cant get a low SWR with my CB
 
I need some help. I bought a uniden pro 520xl and a lil Wilson 3ft magnet mount for my TJ. I have tried every imaginable place in the back and my swr meter is pegged out. I bought an L bracket and mounted in on tire mount, I tried mounting it behind the rear taillight., and I even tried just slapping it on the back bumper and nothing. I even tried grounding all of those locations. I thought it was a short and so I put out the mag antenna right in middle of hood and got 1.5 on both channels!!! Is my whip not long enough? Am I grounding it wrong. ( since it is a mag base I am attaching a ground wire to the L bracket the mag is on and then attaching it to frame. ) i have used a grounding strap and 10 gauge wire for grounding. do i just need to get a non mag antenna and start over?

sparky 04-19-2013 09:59 AM

Mag mount antennas get their signal ground through capacitive coupling of the base of the mount and the flat piece of steel they are sitting on. When you used your hood it worked correctly. Mag mounts are always a compromise, they can be an OK temporary antenna, but they don't have the efficiency of an installed system. Trying to use them without that broad flat piece of steel underneath is difficult.

I think it will be easier for you to go with a permanently attached antenna. A 3 Firestick type with mounting and cable is not that expensive and will perform better.

Giantxtc 04-19-2013 10:56 AM

Thanks! Would I need a longer wip than 3ft if I attach it to the bumper? Does it matter whether the wip sticks out over the roofline?

Jerry Bransford 04-19-2013 12:12 PM

1 Attachment(s)
Probably the best/most popular way to mount an antenna is via a taillight mount like you can get from TeraFlex antenna mounts.

Then mount the antenna using an antenna mount like is shown below, which is a very solid popular way to mount a CB antenna. Just make sure to assemble it properly & place the white nylon insulated shoulder washer properly so it insulates the antenna from the mount.

Mounted via the below antenna mount on a tail light mount, a 2' antenna (like I use) works very well offroad. If you have enough clearance over the top or your Jeep, a 3' would be fine too. But for offroading, even a properly installed & tuned 2' antenna works fine, mine certainly does.

Two good antenna choices would be members of the Firestick FS series family which have a tunable tip for adjusting the SWR. The 2' would be the FS-2, the 3' would be the FS-3.

Giantxtc 04-20-2013 04:55 PM

Thanks guys. One more thing. . As far as the taillight mount, how do you ground it? Where in the mount do you attach the ground and where on the body? Do you have to make a pure metal contact?

lensam 04-20-2013 09:38 PM

The taillight mount is grounded by a screw that comes with the mount. You drill a small hole through the rear of the body( It killed me to do this but ya gotta do it ). You will need to sand the inside where you drilled through to get the proper ground. I got the stainless one from Quadratec because my whole set-up is SS. Heres the pic

http://www.wranglerforum.com/attachm...9&d=1364186573

the Kolector 04-21-2013 06:08 PM

This is what I used: Cool Tech LLC. JK Ultamount CB Antenna System

Giantxtc 04-30-2013 09:02 PM

Ok guys thanks for the advice. I got the connector and firestik fs 3 tunable tip and the teraflex taillight mount. I have it installed and tested swr. It's a little weird. Channel 1 is like 1.8. Channel 40 is 2.0 and channel 19 is like 1.4. What would cause that? I am perfectly content with anything below 2.0 but was wondering why the unusual swr between channels and if there is some trick to get swr lower. I did drill the bolt threw the body and sand the inside edge. Is that bolt enough to make a proper ground or should I use a grounding strap? If so were on the mount do I attach it?

sparky 05-01-2013 10:55 AM

That's normal and correct as is. Your antenna setup is really resonant on just one frequency. When you change frequency the SWR will change slightly. Some antennas are narrow banded, and it does not take much of a frequency change to get it out of the sweet spot.

Your setup is tuned for the middle of the band which is a good place to be. Yep, anything below 2 is fine. Leave it as is and enjoy.

Jerry Bransford 05-01-2013 11:12 AM

Quote:

Originally Posted by sparky (Post 3705842)
That's normal and correct as is. Your antenna setup is really resonant on just one frequency. When you change frequency the SWR will change slightly. Some antennas are narrow banded, and it does not take much of a frequency change to get it out of the sweet spot.

Your setup is tuned for the middle of the band which is a good place to be. Yep, anything below 2 is fine. Leave it as is and enjoy.

X2 on all that.

Giantxtc 05-01-2013 11:16 AM

Thanks guys for getting me squared away. I've learned a lot.


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