CB Antenna, High SWR's

[JBakerFX4]

Mounted a whip & spring on the Passenger side front stake hole mount using the Firestick SS bed rail mount. I've been adding grounds like crazy, helping, but still not perfect. I can't seem to get my SWR's down. I'm at 1.4 & 1.9 reading "short" on length. I see A LOT of Superdutys and trucks in general running a 4' fiberglass antenna behind the cab in this location. Makes me wonder what their SWR's are, or if they even checked them. Any of you guys have this problem also???

[Tim99ws6]

Man o Man i thought i was the only one with this problem! I tried and tried for about a month to get mine ironed out. I finally just gave up and turned off the damn thing. I intend on running it by a CB shop in the future, and letting them iron it out.....I just gave up on the thing. I tell you, nothing frustrates you more than your D-Max and CTD buddies who don't know the difference between a phillips and a flathead screwdriver just throwing on a circuit city special CB setup, and it outperforming mine. It's ridiculous.

[JBakerFX4]

Tim- what were your SWR's? what antenna & mount were you running? Sounds like your buddys need to go play the lottery, b/c they are lucky. Even a blind squirel finds a nut sometimes. I've got 2 big ground straps, one from the bed to the frame, and one from the cab to the frame. (I scratch down to bare frame metal, that blk goop is HORRIBLE!). Under 1.5 is your goal. over 3.0 is dangerous. Mine is on the verge of being good. I might try sanding the underside of the stake hole mount, so the mount itself has a good ground to the bed along with the 10awg ground wire I have running to the mount. Only thing left I can do. I had a 12ga ground wire and switched to the 10ga, made a noticable difference. 1.4/1.9 vs the 12ga 1.6/2.2. So I'm debating maybeing trying some 8ga just for grins. Not sure if it's the Location, or lack of grounding. I think 99% of joe blows on the road with a 4' firestick never check SWR's or even really know/care.

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Last edited by JBakerFX4 : 10-01-2007 at 05:04 PM.

[Tim99ws6]

Im in near the same boat. Mine are up at 1.5/2.0. I gave up after i got to that. It was dagerously high like you said. I had to add a dedicated ground strap, get a decent ground, etc to get to that point. As for my mounting point, its at the front of the bed, on the top of the front.

[JBakerFX4]

Tim- you have any pics of your mount? Under 2.0 won't hurt anything, but I really like the peak performance factor of being under 1.5. I have 4 things I plan on doing then I am out of ideas. 1- Sand stake hole mount underside 2-Add another bed ground strap on the other side. 3- Add another ground strap on the other side of the cab. 4- Up the AWG of the ground wire from 10 to 8. After that I'm clueless. I'm gonna give up after that. I've already been using it with the current swr's and it works good.

[JBakerFX4]

Ticked today, went out and sanded the underside of the stake hole, put it back together and now the SWR's are back to 1.6/2.2 like before I grounded everything. Only thing I've done since I got it down to 1.4/1.9 was throw paint on the frame grounds to keep the frame from rusting.

[geekdownrange]

Originally Posted by JBakerFX4

Ticked today, went out and sanded the underside of the stake hole, put it back together and now the SWR's are back to 1.6/2.2 like before I grounded everything. Only thing I've done since I got it down to 1.4/1.9 was throw paint on the frame grounds to keep the frame from rusting.

Have you tried removing the spring and rechecking? There is only so much adjustment in the tip of the antenna. The spring shouldn't cause major issues, but all the "normal" fixes aren't doing it. Time to check out the weird stuff.

A good setup would typically be a short pieced of tinned copper grain from the mount to a good ground. 6-12" or less is best. The bed rail isn't a great location, but better than some.

As a temporary check, you might try moving the mount to the rear stake pocket. Since that will move it further from the cab, you'll add distance from a big chunk of metal parallel to the antenna that may be coupling into the antenna system. If you do this as a test, a try both with and without the spring may be a good idea.

How are you for grounding at the radio end? A good solid connection from the chassis of the radio to the truck chassis? Backing that one up with tinned copper braid isn't a bad idea there either.

Do you have 5-10ft piece of coax and a coupler? Some lengths of coax can work against you by creating a large impedance transformation. By changing the coax length slightly you can make sure you're not hitting one of those cases.


-Brian

[orangesbc383]

ive got a mini will antena and all i do is put a little piece of paper towel under it (cut it out just enough to cover the base) and hook it up im at 1.1 i tuned in once worked great!! untill i want to mount it for ever. i want to keep the sleek look for now.

[JBakerFX4]

Yeah, I bet a med sized mag mount would outperform my whip where it's mounted and with those crappy SWR's.... sad. I really just wanted a 4' wilson there on the bed rail... but that idea is fading fast. I've tried with and without the spring. it's worse w/out it. It's reading short, so the spring made it a tad better. I've sanded the underside of the stake hole mount to ensure the mount itself has a good ground to the bed, run a 10ga wire from the mount to the frame, Added a ground strap from the Cab to the frame, bed to frame and from cab to bed. 1.4/1.9 is the best I can do. I finally got them back down today.... just can't get lower than that.... FOCKER!!!!! Time to think about an antenna that WILL work/tune. Thinking a Wilson Trucker with a 17" or 22" shaft in this location, OR a mag mount on the roof. just not sure what to do with the coax routing, and I don't like the idea of the magnet coming undone at 95mph on the interstate.

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Last edited by JBakerFX4 : 10-02-2007 at 04:26 PM.

[JBakerFX4]

Forget it. Going with a wilson 5K mag mount. going to route some coax permanently in the truck. (the mini 8 I currently have). so I can remove the mag mount quickly w/out having to mess with coax running in the truck. so the only think you'll see is coax running behind the cab down inbetween the bed. OH well, not bad really i guess.