i installed a CB into my truck the other day and i was getting alot of static and people were faint. the CB i got is probably over 15years old but i was wondering were i should put my 2 freightliner antenea( dunno how to spell heh) right now i got them on either side of the box right behind the cab... as in touching the cab. i was told that that was a bad place for it because i am blocking the front direction of the reception because of the cab in the way... i don't know if thats true or not so i came here to see. if it is does anyone have some suggestions on where (and how prefferably) to put them because i would like to get better reception.

i own a 1991 Ranger

 

Willie...
I had my CB antenna on my ol' Ranger off the rear bumper, off to the driver/left side corner. Other than being a 9'-0" stainless whip, I had lit'l to no issues getting or rec'ving communications. I only had some occasional interference from my other radios and trunking modem on board.

So....
I would make sure your surely footed into a good ground, even run one of those braided grounding straps from the ant. mount to the chasis if you have to. I would also Double check all of the terminations (radio-->antenna) and your cable routing.

One other thing you have to keep in mind are your surroundings. I personally probably wouldn't mount an antenna directly behind the cab.

Instead I would either go with an NMO mount or purchase or make a angle bracket to mount to the underrail section of the bed (lit'l further back). You have to really think about the NMO mount... are you really going to be hanging on to the truck for a long time? The NMO mount in the top-center of the cab, would probably be the best spot. Note: The reason I didn't do the NMO mount for the my antenna is b/c of my existing antennas from other projects just would not mount to the typical NMO bases.

The alternative for the drilling/NMO mount, would be a magnet mount, there are quite a few vendors for the mag. bases. You also have to remember that you'll have the cable visible running down the cab and where-ever else, and you'll have to remember to take off the antenna/base to wash/wax underneath it and the cable routing area.

The "Freightliner antennas"... are those the 3' white fiberglass ones; top-end loaded? ...if so the Larger mag. bases may be one of the better options besides the bedrail mount.

 

I have a nifty Antenna Placement and Trouble-shooting guide that I had found somewhere(?). It's a 2.3MB PDF file so its too big to put on here. You can shoot an e-mail to me and I'll upload and send it to you. The guide is basically based off a actual (18-wheeler) "Rig" placement but it has good ideas. It also shows the methodology behind the form and function of the CB...antennas and communication, and how you could apply it to help ensure you get the best communications for your set-up.

 

I got a CB in my '94. I used one of the magnetic antennaes, ran the wire from the CB through a grommet under the carpet, back to the rear of the regular cab, up just to the left of the rear window, and put the antennae above the driver's side of the rear window and just pushed it over far enough to keep the antennae tight. It doesn't work well around town...but once I get over near any of the highways it works great.

RP
Zach

 

i ran my ground wire where there is already a grounded wire to so i don't think that would be a problem.when you say to use a braided grounding straps from the antenea mount, are you talking about the actual mounting bracket of the antenea or are you just talking about the negative wire being grounded...
i don't really want to get a magnetic one because i am very forgetful so i don't need to be missing it heh.
what by the way is an NMO.
The anteneas are freightliner ones like they use on the big rigs, they are about 3' but i dunno if they are made of fiberglass or what.

thanks

 

Most of the co phased, dual big rig antennas, are designed to be placed on the big trucks mirrors, away from the cab, at a 6 foot separation from each other.

They then broadcast most of their energy fore & aft, with smaller left & right, side lobes of radation, so your sending & recieving will be stronger in the direction the truck is facing & to the rear, less so to the right & left sides.

You are correct, having them close to the cab isn't a good place at all. Bet your SWR is high there too, so it should be checked ASAP!!!!

Agree with a good ground being needed.

Generaly the antenna needs to be placed as high & unobstructed on the vehicle as possible, with as few bends in the coax cable & the CB radio & antenna need very good, clean & tight ground connctions.

Then the vehicle should be moved to an open area for antenna tuning.

An area with no metal fences, poles, overhead wires, other vehicles, or buildings close by & then close the vehicle's doors, move other people away or put them in the vehicle while tuning & check the systems VSWR= Voltage Standing Wave Ratio, which is a measurment of how well the antenna & connecting coax cables impedance is electrically matched to the radios tansmitter impedance.

It should be 52 ohms for best match, but most stick antennas can't do this, so they must be tuned as best they can, with their placement & tuning stub length.

Some radios had a VSWR measuring capability built in, so you could fine "tune" the antennas impedance to the radio, for the lowest VSWR possible.

I like to tune mine close to the middle of the CB band, around channel 19, then go to channel 1 & 40 & see how their "match" is.

If it's higher on channel 40 than channel 1, shorten the antennas tuning stub in about 1/8 inch increments. until channel 1 & 40 have the same VSWR reading, then you'll have the best overall performance for all channels.

High VSWR means a poor impeadence match, between the radio & antenna & less of the transmitters power is being radiated from the antenna & more of it is being reflected back into the transmitters final power transistors, not a good thing!!!!!

This impeadence mismatch (high VSWR, sometimes called SWR or bad match) can cause the final RF power transistors to over heat & fail, so if you have this problem, don't do much if any transmitting, until you put it right.

A low VSWR will improve your radiated RF power & range. It'll also improve your "ears" or recieve signal, so it's plenty important you pay close attention to getting it right.

Let us know how you do.

 

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thats the cb i got the trc-469. i don't know if i have a swr meter nor do i know what it is.

so the antena mounts do need a solid ground.

my coax cable is REALLY long. its so long i can run the cable from the front to the back of the truck. and its all just sitting on the floor under my seat.

VSWR= Voltage Standing Wave Ratio i have no idea how to measure it nor do i know if i have a guage for it. and what is the tunning stub length??

holy crap... i put a cb radio into my truck cause i thought it would be fun and cool but i had no idea there is a freaking science to all this... sooo confusing too heh. but i will do my best...

do i have to buy all those meters or is there a way to check it without buying them.(i'm poor so less money is better heh)

 

SWR was the first thing that crossed my mind as I read about the problem. If your radio doesn't have one, you need to buy or borrow a SWR meter. They are fairly inexpensive.

 

Nope that puppy doesn't have a built in SWR bridge, so you'll have to use an inline SWR meter, to measure your setup's SWR.

On a co-phased antenna like you have, both antenna tuning stubs must be adjusted at the same time, so both halves of the antennas stay in tune.
These tuning stubs are located atop & in the center of, each antennas loading coil.
You probably have about 18 feet of coax cable feeding this dual setup, so you want to make the coax loops as large as possible. DON'T make the loops small & tight, or put a crimp in it, as this will make the SWR worse.

The tuning stub is usually held in place with a set screw, thats loosened so the wire stub can be raised or lowered to slightly lenghten or shorten the antennas length as needed, to adjust its impedance & there by adjust it's SWR. Some antennas have a threaded tuning stub, thats screwed in & out, to do the same thing.

This isn't something a first timer should attempt, unless you have some experienced help, or you have done plenty of reading on the subject.

You might find enough on line info with persistant searching, or a look in your local library for publications on mobile antenna installation & tuning.

Or if your into doing this yourself, sounds like 99Trigger has you covered with a publcation that he could send you.

If you have a friend or know someone thats into Ham radio, they would probably have a swr bridge & could help you properly install & tune your set up.

Otherwise it might make more sense to take it to a truck stop cb radio shop & pay them to deal with this.

If the SWR is really high, you could wipe out the final RF power tansistors by holding the mike key down too long & over heating them.

Let us know how it goes

 

oh sure scare the crap out of me!! heh. i know nothing about the cb/antenna's /anthing else to do with them... so basically i'm going to have to find a 4x4 shop or someone who knows how to tune cb's and such correctly... in the long run it might be cheaper just to buy a slightly newer cb to have that swr bridge.

i have no idea where a truck stop cb radio shop is anywhere around the Vancouver Canada area... i wonder if the phone book would have it...

 

Well most big truck stops have a CB radio shop in them, usually staffed 24/7.

Not trying to scare you, just trying to alert you, so no damge is done to your rig.

Once you see the tuning done, it's not bad at all & I know if I can kearn to do it you can easily learn to do it too!!!!

A CB can be fun & useful too, on trips.

I always have mine on "copying the mail" as I travel. I have avoded countless traffic backup's from accidents, to construction, to congested times & areas, by taking alternate routs, to finding open gas stations during gas rationing days once.

My CB's also have a weather band on them, so I can keep in touch with the local weather conditions when traveling.

Yup when traveling I don't feel complete, without my CB in & on!!!!

 

geez i dunno how far mine even goes lol. maybe i will see if i can find a truck stop around here... are weigh-in stations the ame thing? i dunno if we have any truck stops... and i think the weigh in station is closed down lol

 

I use to have a 102" whip antenna that attached to the rear bumper, and bent to the front with clip. It provided great reception and could get out great.

 

Well here in the States, most big truck stops are located along our major intestate highway intersections or frequently traveled exits along those kinds of roads. I should think Vancoover BC would also have it's share of stops too.

You should be able to find a listing in your local phone book yellow pages under "truck stops" or "mobil communications", or such.

Anyway hopefully when you get the antenna properly installed & tuned, it'll work to your liking.