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If you have a fiberglass antenna and high SWR read this!

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Old Sep 18, 2009 | 12:25 PM
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Exclamation If you have a fiberglass antenna and high SWR read this!

In a previous thread I mentioned I had a new 4' Wilson I swapped for a Firestick because the Wilson had high SWR (excellent RX crappy TX) right out of the box.

Anyway, something I read a few months ago popped into my head today and that was something about not running a ground strap on an ant on a big truck antenna unless you had to.

So I proceed to screw my Wilson fiberglass antenna into my slim mirror antenna mount on the back side of my 3rd brake light EXCEPT I didn't ground it this time.

Guess what?

BAM!

Sub 1.0 SWR without any tuning!

Not only am I getting 'lean and clean' radio checks from my driveway which is 4 miles from I-75, I can hear and talk to the 10-4 truck stop and truck wash which is 15 miles north of my location.

All because I DID NOT GROUND THE GROUNDING STRAP ON THE ANTENNA!

I revealed this epiphany to a buddy of mine who I gave my tuned up Texas Ranger CB to and who also has every Ham license there is (a 39 yo Elmer ) and he wasn't surprised.

He said the antenna should be grounding through the CB via the cable. He also said most likely I was getting a ground loop causing high SWR into the radio which would have eventually burned the radio out.

So why did the Firestick work? It didn't have a ground wire on it.........

I hope my experience helps you!

-42 Driver?

Last edited by RATM; Sep 18, 2009 at 12:29 PM.
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Old Sep 18, 2009 | 05:19 PM
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I had just the opposite happen to me. I have a 3' firestik mounted to the spare tire bracket. My swr was pegged. I ran a ground wire from the tub to the antenna mount and I got a reading of 1.5. CB is so wierd how every situation is so different. Oh well. Glad you got it up and running.

Also, don't think your "USSA" went unnoticed. I've been saying that for many many months now.

Last edited by rich1340; Sep 18, 2009 at 05:23 PM.
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Old Sep 18, 2009 | 05:24 PM
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interesting i think i may take the ground strap that is on the antenna itself (wilson) off and see if i get out better. Right now my transmitting range SUCKS, receiving is much better.
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Old Sep 19, 2009 | 04:03 AM
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Originally Posted by RATM
... Sub 1.0 SWR ...
By definition, that can't be (unless maybe you're drawing in power from a parallel dimension to send out the antenna with your radio's RF!). I expect you mean 1.0:1, which is perfect (every bit of RF power sent to the antenna was radiated).

Last edited by Mark Doiron; Sep 19, 2009 at 04:05 AM.
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Old Sep 19, 2009 | 08:23 PM
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Originally Posted by rich1340
I had just the opposite happen to me....
I also just went through this with a cheap Fry's brand antenna. I had a really high SWR and as soon as I ran a groud it droped down to about 1.6:1.
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Old Mar 9, 2010 | 03:13 PM
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ok, so i'm not hugely educated on CB's so bare with me here. I have an older cobra model cb that I had that used to be mounted to an 84 bronco of mine. had it hooked up and worked great. low SWR. I recently installed it on my jeep with a fiberglass antennae and mounted it with sheet metal screws to the rear side of the jeep....I have a really high SWR...it's almost in the red when I click the mic. Am I having a problem with it because I just screwed the mount to the side of the jeep? or something else It seemed like a good idea at the time.

Also, I can hear everyone fine on the highways and when people have tried to talk to me through theirs, but it seems that no one else can here me when I try talking...any ideas?

After reading the posts I'm wondering if it's because it's didn't need to be grounded and now it is...to my jeep

Thanks for the help.
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Old Mar 27, 2010 | 02:27 PM
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Originally Posted by VaNomad0530
ok, so i'm not hugely educated on CB's so bare with me here. I have an older cobra model cb that I had that used to be mounted to an 84 bronco of mine. had it hooked up and worked great. low SWR. I recently installed it on my jeep with a fiberglass antennae and mounted it with sheet metal screws to the rear side of the jeep....I have a really high SWR...it's almost in the red when I click the mic. Am I having a problem with it because I just screwed the mount to the side of the jeep? or something else It seemed like a good idea at the time.

Also, I can hear everyone fine on the highways and when people have tried to talk to me through theirs, but it seems that no one else can here me when I try talking...any ideas?

After reading the posts I'm wondering if it's because it's didn't need to be grounded and now it is...to my jeep

Thanks for the help.
i know this is older, but did you tune your antenna when you put in on the jeep? the antenna needs to be lengthened or shortened when its moved.
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Old Mar 29, 2010 | 10:20 AM
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Originally Posted by RATM

<snip>

So I proceed to screw my Wilson fiberglass antenna into my slim mirror antenna mount on the back side of my 3rd brake light EXCEPT I didn't ground it this time.

Guess what?

BAM!

Sub 1.0 SWR without any tuning!

Not only am I getting 'lean and clean' radio checks from my driveway which is 4 miles from I-75, I can hear and talk to the 10-4 truck stop and truck wash which is 15 miles north of my location.

All because I DID NOT GROUND THE GROUNDING STRAP ON THE ANTENNA!

I revealed this epiphany to a buddy of mine who I gave my tuned up Texas Ranger CB to and who also has every Ham license there is (a 39 yo Elmer ) and he wasn't surprised.

He said the antenna should be grounding through the CB via the cable. He also said most likely I was getting a ground loop causing high SWR into the radio which would have eventually burned the radio out.

<snip>

-42 Driver?
The little wire on the bottom of Wilson 'glass antennas is not a ground wire. IIRC it changes the impedence of the antenna and will move the resonant freq of the antenna ~ 20 channels. It would be a very strange case, IMO, that it would be used. Shoulda read the instructions!
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Old Apr 3, 2010 | 04:05 AM
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I am wondering if someone could post a picture of what they have as a "ground strap." I just changed from my hard top to soft top and my SWR went from 1.2 on all channels to 2.5 on all channels. So, I know that the length of the antenna is ok, but I might need a better ground now.

Thanks in advance.
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Old Apr 3, 2010 | 02:07 PM
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I just used a shortish length of 12ga wire from the bottom of the antenna stud to a spot on the inside of the tailgate under the plastic. That's on a spare tire carrier mount.

Braided ground strap is better, but I didn't have any.
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