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9 foot CB antenna on bumper...SWR?

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Old 08-19-2005
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9 foot CB antenna on bumper...SWR?

I plan on getting a 102" foot steel whip, on a stainless steel spring with a bumper mount and 18 feet of the highest quality coax with a good cobra radio.

The radio is already in and running, I just need to know if the bumper mount will provide a good enough SWR. I'm looking for at least 1.5:1.

I've heard on a bumper mount there's not enough reflective surface of ground planes or whatever.

Anyone have a bumper mount and measured their SWR...or anyone have a bumper mount without measuring their SWR and have good reception/output?
 
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Old 08-19-2005
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I have my 102" steel whip mounted on the bumper and my SWR's are 1.3:1 Almost Perfect!
Make sure you ground it good.. and try not to coil up the extra coax! those the main things..
you shouldnt have any problems with SWR's whit that antenna and 18' of coax!
but if you are just using it on the trail it doesnt really matter!
I talk skip on mine and have a few amp for my radios ... All depends on what you want to use it for!
 
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Old 08-20-2005
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Exactly what I was looking for! Thanks a bunch!
 
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Old 08-20-2005
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The steel bumper is attached to the steel frame which is attached to the steel body. You'll have a nice ground plane in the fron-right diagonal and no ground plane around the left to the rear. It's going to give you an awkward radiation pattern. A lot of people do it and it isn't a make-or-break difference, just not optimal.

Repeat after me: I DO NOT NEED 18 FEET OF COAX. I DO NOT NEED 18 FEET OF COAX. I DO NOT NEED 18 FEET OF COAX.

This alleged "optimum" length of coax BS has been floating around for many years, spread by alleged "experts" and ends up screwing over the end user. So many people say it, the poor guy who doesn't know any better will believe it no questions asked it. The optimum length of coax is as little as possible. You want only as much coax as it takes to go from the antenna to the radio with a little bit of slack to work with in the cab. If that is 7' or 20' or 384', it doesn't matter. This of course is as it applies to single antenna installtions. When you get into co-phasing, length matters.
 
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Old 08-20-2005
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Well is my range going to be messed up or anything? Is it going to mess up much? I was using a little mini radioshack cb with a 50ish inch antenna in my last vehicle, will it be at least as good as that?

And I'm only getting 18 feet of coax because that's all thats sold in that length. I hope it's enough to be honest. Will it be? From the bumper to where a manual shift **** is?
 
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Old 08-20-2005
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i have no idea what you guys are talking about

i had a cb..i sold it....i never got good reception

i wanna be able to talk to people in another state....

once, due to the weather, i picked up a crystal clear convo with two guys in california...
 
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Old 08-20-2005
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I just installed a 102" from rat shack on Thursday - It grounds fine to the bumper. I've got 15' of coax and it reaches from the cab to the rear with no problems.

Don't ask what my SWR is - I haven't checked......however, I've easily gotten a good 10 mile range from it. Verified by some nice truckers who were looking to chat......

And don't forget to buy some tennis ***** unless you really hate your paint.
 
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Old 08-20-2005
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could i mount an antenna thru the little hole infront of the liscense plate on the rear bumper? i dont really wanna drill a hole....
 
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Old 08-20-2005
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Originally Posted by TippnOver
could i mount an antenna thru the little hole infront of the liscense plate on the rear bumper? i dont really wanna drill a hole....
You can BUT you would have to take the antenna off to get the tailgate down!
also the hole maybe to big for most mounts!
 
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Old 08-20-2005
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There should be a CB for dummies....i have 2 cb's....ones a 40 channel digital cobra and the other is a manual 30 channel cobra....but i couldnt ever find an antenna that would get good reception....and if i did hear anyone talking, i couldnt talk to them...i know NOTHING about cb's really so, do i just need to find a good antenna?

Rocky
 
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Old 08-21-2005
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There are holes already in the bumpers. Look on either the right or left hand side where the tail lights are - you just have to punch a hole through the plastic on top of the bumper.
 
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Old 08-21-2005
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ah! sweet!

i'll check it out now!!

but i doubt mine will have that

i got a chrome bumper...also...a mazda
 
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Old 08-22-2005
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If installed correctly, the 8' whip on the bumper will probably out-perform any crap-shack magnetic antenna. This will probably make up for any imperfections of the antenna being mounted on the edge of the ground plane. The only time you might notice the difference is talking to somone REALLY far away, it might work better if you point the nose of the truck in that direction. For average use though, it will be fine.
 
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Old 08-22-2005
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just looked...no hole...dammit....
 
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Old 08-23-2005
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Originally Posted by FireRanger
If installed correctly, the 8' whip on the bumper will probably out-perform any crap-shack magnetic antenna. This will probably make up for any imperfections of the antenna being mounted on the edge of the ground plane. The only time you might notice the difference is talking to somone REALLY far away, it might work better if you point the nose of the truck in that direction. For average use though, it will be fine.
I'm not looking for super far range. Just interstate chat with truckers and 4 wheeling buds on the trail. Maybe 1 mile max outside the city...in the city maybe 500 yards.

But I do want to have that extra ability to "reach out and touch someone" just in case. Which is why I don't want a magnet.
 
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Old 08-25-2005
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I bought the 102" whip, but now I'm looking at mounts and how I would set it up. How'd you guys do it?

Did you lay the metal bracket on top of the plastic step liner or underneath it?
 
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Old 08-25-2005
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And about how much do these things bend when you're driving down the road? Do I HAVE to use a spring? Would a spring make it bend much more when you're driving?

I just don't want it hitting the guy behind me when i hit the gas or slam on the brakes.
 
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Old 08-25-2005
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put the metal under the bumper

and they'll bend a little...the springs are needed so they dont snap in some odd event

but u wont smack the guy behind u...add a tennis ball on there, to protect u're paint, and possible protect anything else it may hit

i think alot more people on here have Firesticks...that wont bend at all....
 
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Old 08-25-2005
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Oh, I see what you mean now. Just leave the bolts on top. I haven't seen the mount yet, so I don't know what to expect.

That plastic step cover, that snaps off right?
 
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Old 08-25-2005
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i believe so...

but u might have the little circle that u can just pop out...

i dont :(
 
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Old 08-26-2005
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On the steel bumper or plastic step?

I don't see a hole on the plastic step.

And is there an alternative to tennis *****? Not that I have a problem with it, just looking for uniqueness.
 
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Old 08-31-2005
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I got it installed. 18 feet of coax provided 3" of slack at the end. I don't know what truck you have 01rededge...wait...nevermind haha.

SWR on Channel 1 is 1.3 and on Channel 40 is 1.5, and that's using a good meter.

Definitely acceptable. Is there any way to tune a 102" whip though?




I should've used the flash in that last pic. Got a good shot of my CB speaker :)
 
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Old 08-31-2005
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The only two reasons that your SWR is above 1.1 is that there will be a small amount of reflection of the antenna against the bed where the antenna is below the top of the bed.... and while the antenna is grounded to the bumper which attaches to the frame.... I would attach a short length of braded grounding strap directly from the antenna base to the frame rail.... The additional grounding may drop your SWR slightly....

OR 4x4
 
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Old 09-01-2005
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Alright, thanks alot!

Where can I get grounding straps?
 
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Old 09-01-2005
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Most of the time I get mine from a electrical supply warehouses or a industrial liquidator....
If you have a Fry's Electronics.... near you.... they probably sell it....

OR 4x4
 


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