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PLEASE HELP!!! High swr on my roof rack mounted antenna

nmpfeiff

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I am fairly new to CB radios so I have a question about my radio and antenna setup. Everything seems to be working fine but I really do not know how good one should work. I am going to give you guys some details of my setup and see what you think.

I have a Cobra 29 LTD Classic mounted to the side of the center consul with Velcro. I have the coax running under the seat throwing the back door to my antenna. I have a ground wire running from a bolt under the seat to a screw on the side of the radio.

I have a 3' fiberglass antenna made by diesel electronics that I got from a truck stop. I have the antenna mounted with the clamp that came with it to the stock roof rack that is made out of plastic. I know the roof rack is not grounded but I do not know if that leads to the problem below.

The problem is I can't get the swr meter built in on my radio to get below 3. I have tried running a ground wire from the mounting bracket to the same bolt I grounded the radio but that made the swr worse.

Has anybody got any ideas since I have tried many different things. Do I need to ground the antenna? Right now I have the ground wire off and I can't tell a difference. I think this may just be a problem with the built in meter on the radio.

Sorry for the long post but i want to make sure I put in all the details.
 


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corkey

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well, you do need a better ground,, the wire running back to the seat bolt is not a good idea , it could cause a ground loop,,
another problem is the smallish length antenna, i would experiment with other placements, to find out if there is a better place ,
the meter,, hmm, did you calibrate it properly ? you have to set the output before you measure the reflected swr, you set the button to cal, and adjust to the set mark, than flip the switch to swr,, that gives you the accurate swr,,
 




fixxxer

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If you are not sure if you are getting an accurate reading, borrow a friend's swr meter or get an external swr meter. A compact SWR meter shouldn't run more than $15-$20. Here's a great guide by Firestick® on how to check your SWR and adjust the antenna and coax. http://www.firestik.com/Tech_Docs/swr-intro.htm Remember, when you check your SWR, you are testing all the components (antenna, radio, coax, ground-plane) and each will have a bearing on the final reading.
 




nmpfeiff

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Thanks guys for the quick response. I have flipped the switch all the way down and calibrated the meter. Then I flipped the switch back to the middle to check the swr. I have a old swr meter but I can't get it to work.

My dad said the same thing about ground looping and I believe that may be the problem. I really do not know where to ground to on a 2002 Ford Explorer beside the seat. I do not want to drill any holes.

Do you have an idea on a good ground point and do I really need to ground the radio? Another thing is I have it powered to the cigarette lighter.
 




Donner

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Mine is grounded to the passenger seat... I have no problems with it. The antenna I use is a magmount that I place on the roof of the vehicle when I need it. My problems with reception/transmission/swr was the antenna - wrong type. Magmounts seem to work best... I had to strap the antenna to the roof rack when driving over 60mph, but no problems after that...

I can only recommend having more than one antenna to use (trail/hwy) and probably try out the magmount...
 




nmpfeiff

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Do you mean you have the radio grounded or the antenna grounded to the passenger seat? The reason I am asking is I did not think you had to ground a mag mount antenna since it got its ground from the roof. I tested the radio and antenna the way it is with the ground wire off the bracket and I am getting about 6 miles receiving and transmitting on fairly level terrain. I use it mostly for the interstate any way.
 




rizzjc

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No, you don't ground the mag mount. And you never ground the ANTENNA. You ground the mount. 6 miles is pretty good with a cb. You might get 10-12 max. I doubt you'd get much more than that under anything but perfect conditions.
 




nmpfeiff

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Ok thanks. I knew that you do not ground the antenna but the mount. I believe I am just going to leave it alone and not ground the antenna since the swr is higher with it grounded. That is the only reason I got concerned because when I grounded it the red light on my radio came on saying the antenna was malfunctioning.
 




rizzjc

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That sounds like a plan. If it ain't complainin' then leave it alone. ;) On my stock roof rack there is SOME metal. It wouldn't be a great ground, but it would probably get a ground. Not sure if that's the same with yours. What SWR do you get with it ungrounded?
 




fixxxer

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The problem is I can't get the swr meter built in on my radio to get below 3. I have tried running a ground wire from the mounting bracket to the same bolt I grounded the radio but that made the swr worse.

Read his 1st post
 




nmpfeiff

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I get around a 3 ungrounded and a 3.5 grounded. What model explorer do you have? Mine is a 2002.
 




rizzjc

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'97 here, but I could be wrong on the grounding. I know my current rack does not, 'cause i replaced the stick with a Yakima. Anyway, sounds like a little tuning on the antenna is needed to get your SWR down a bit more.
 




nmpfeiff

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OK thanks for all the help. I am just going to keep trying different things to get the swr down. I may take it by a friend's who owns a trucking company since he can look at everything in person.
 




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