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cb antenna

Dain Bramage

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so, i just picked up a new uniden cb, and i am trying to get it wired up. does the antenna have to be isolated from (i.e., not grounded to) the body? i have the antenna mounted directly to my front bumper right now, and it no worky. but it works with the magnet whip antenna i have.
 
The center wire in the coax needs to be isolated from the body. The outer braid needs to be grounded though.

so, i just picked up a new uniden cb, and i am trying to get it wired up. does the antenna have to be isolated from (i.e., not grounded to) the body? i have the antenna mounted directly to my front bumper right now, and it no worky. but it works with the magnet whip antenna i have.
 
does it have to ground out in the radio? i checked continuity of the coax, including the antenna, i have continuity both with the antenna mounted on the bumper, and without.

here is how i did the test. the clamp is on the center pin, and the probe is on the metal sleeve that appears to be isolated from the center pin.
 
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well, i have it working, put a plastic washer on one side, its rough, but it works. i think that if i can get it isolated from the bumper, it will work good.
 
so now i can recieve, but it isnt seeming like i can send. i tried 8 and 11, the only channels that i can hear people talking on, and they dont seem to be able to hear me. i havent had my antenna tuned yet, tho, and i dont know if that could have anything to do with it. anyone in monroe/snohomish want to try and talk to me?
 
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I would not key the CB too much until you get it tuned. You can burn up your radio if your VSWR (Voltage Standing Wave Ratio) is too high >2+. The higher the VSWR, more power is being reflected back into the transmitter, and not actually leaving the antenna. Go to Radio Shack and get a SWR meter or borrow one from someone before you ruin your CB.
 
do you have a pic of you cb?
You'll hear talk on it from the trucker's but most of the time their CB's have been tuned..so they can send out alot farther.my unieden reaches out about two miles max.
I need to get mine geeked and tweeked..
 
ya. its a uniden pro 510xl.

crappy cell phone pic. the mic feels kinda cheesy, tho.
 
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When I was a kid I made a home base station antenna out of an 8ft fiberglass whip clamped to a vent pipe on the roof and a ground plane out of like 100ft of aluminum wire fanned out and stapled onto the cedar shake roof. I used to be able to talk to my buddy who lived about 7 miles away and we still have a truck stop between us (generating tons of noise into the frequency band). So depending on how high up your antenna is, or if you live on a hill or mountain, you can get better transmit and reception.
 
does it have to ground out in the radio? i checked continuity of the coax, including the antenna, i have continuity both with the antenna mounted on the bumper, and without.

here is how i did the test. the clamp is on the center pin, and the probe is on the metal sleeve that appears to be isolated from the center pin.

alot of glass antana's have a choke in them that grounds it, so w/ a vom it'll show continuity...

are you useing an ant mount? or just a hole drilled in the bumper?
 
Are you using one of the stud mounts? (The one that has the bolt, and the nut and the nylon isolators) You need to make sure that the antenna center conductor is not grounded. The best thing to use is one of the ones with the nut on one side that the antenna screws into and the SO-239 connector (female coax connector) on the other side. I usually make my own cables since the ones commonly available are crap and are often corroded inside. Also I recommend using RG-8 cable (it is a fat one with a stranded inner and outer conductor) as it is better.
 
i dont really know what all you just said, but everything i have i got from napa, including the coax cable. and i wont be keeping it on the bumper, i dont like it there. i will be relocating it to my toolbox. where it is it isnt above the cab of the truck, and there is no room to put a spring on it, if i did it would hit the bar on the bumper and the corner of the hood. i guess i will be getting a spring and another nylon insulator. i believe it is a stud mount.
 
The SO-239 connector is the one that is on the back of your CB. They make a mount stud that the antenna screws into the top of, and the cable attaches to the bottom of with an SO-239 connector. This is good because you don't need to worry about a short as long as you have the nylon isolator installed between the stud and the mount surface. Something like this:
http://www.www.premiere-electronics.net/store/k4a.html
 
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Do yourself a favor, go to Radio Shack and buy an antenna mount. Just a few bucks. Install the mount, then the antenna. Then retest the system. Money well spent. $5-10.
 


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