Ok I got my new CB radio. It is a Cobra 18wxtsII, Not a real expensive model but hopefully one good enough to do the trick. Here is my delema, I ran the coax out the fire wall and along the frame to the bed where I have the dual antenna's attached to the truck box. The 18ft rg-59 dual coax will not reach the passenger side. I know that from the split the coax needs to be the same length, so I got a 5 ft piece of RG-58 single phase coax and ran it from the radio to the split (RG-59) dual phase. Is there any reason that this should not work? Is there any difference in RG-59 vs RG-58? other than the actual split? I can hear people talking on the radio but only 1-3 channels, and for some reason no one will answer me or they cannot hear me.

Note: I am at the fire station today and I am curious if maybe the radio tower at the stn is possibly affecting my CB's ability to transmit and recieve. The people I hera on the CB talking are from Georgia and New Jersey, I am in Arizona????

Thanks for the help.

Fire Rooster

 

Yes there is a big difference between the two. RG-58 is 50 ohm cable, and RG-59 is 75 ohm. You'll never get the SWR adjusted properly. Use 50 ohm cable only. RG-8X or RG-8U would be a good choice for all of it.

 

The antennas came with the RG-59, though

 

Fire just a thought, if your box is aluminum you might need to run a better ground to your antenna mounts.

RubberDuck

 

Do yourself a BIG favor. Don't connect one of the antennas. You can keep both up for looks. But not as good as just one antenna.

First you need 8' between the antennas and you don't have that much.

Second if you use two you will talk and hear directional, which is good for truckers who are steady going staight down the HWY. You need to get out in a big oval.

Third Make sure your antenna is grounded. Or your box is grounded to the truck good.

Tune your antenna for SWR's with a meter.

Drilling a hole in your roof and using a Wilson 1000 will give you the best performance for your buck.

Take a look at this site, It is a good site I have not seen it for a while but I do belong to their CDX Club. http://pub86.ezboard.com/bworldwidecbradioclub

Antennas are the most important part of the radio. Don't go cheap on this because you will not talk as far as you should or could.

73's Erik


I just looked back at your other post and it say's your using Wilson Mag mounts? Is that still the case. Trust me slap ONE of them up on the center of your truck roof and tune. I bet you will see a big difference just to start.

The mag mounts are not made for co-phasing at all.


What your hearing is called skip, your ststion tower is helping some with that but some of them are also pushing 1-2 thousand watts you can hear them by sticking a coat hanger in the antenna hole.

You Have to tune your antenna somewhere where there is no wires or buildings. Turn your radio to ch. 20 and go for the lowest SWR. Ch.20 will give the best in the middle SWR for all of the 27 band.


How do I tune a CB antenna?

Simple. From the beginning. Mount the antenna as near the middle of the roof of your vehicle as possible. This will give the antenna a nice even ground plane. Route the cable to the radio-avoid pinching it or running it next to electrical wires. The SWR meter can be installed anywhere between the transceiver and the antenna. Most mobile antennas have only one connection point. The easiest setup is to have the SWR meter directly after the radio.

Radio-SWR meter-antenna. Easy as that. Make sure the SWR meter is designed to work on the frequency range of 26-27 MHz. Hook it all up and pick a channel. I generally start on CH 20. Key the mic and watch the SWR...where's it at? Is it over 1:5:1? If it is, then go to CH 40, key the mic again..what is the reading? Remember it. Then go to CH 1, key the mic and check the reading. If the SWR reading is higher on CH 40 than it is on CH 1, the whip needs to be shortened. If the SWR reading is higher on CH 1 than it is on CH 40 the whip needs to be lengthened.

Easy way to remember that-Higher on the upper, shorten If the SWR is higher on the upper frequency, shorten the whip. Vice versa if it's the other way.

Adjusting the whip takes a little time & patience. Nomatter which way you're tuning it, do it in small incriments, approx 1/4 inch at a time. After each adjustment recheck the SWR on CH 1 & 40 until you find your correct tune. Ideally you should be able to get 4 watts driven with about 1/2 watt reflected. Equals about 1:5:1.

http://www.wilsonantenna.com/nognd.htm
Also check out this siteif you insist on going with two antennas

 

how do I better ground my antenna's? I am not really keen on drilling holes in my truck, and that is why I have them mounted on the box.

 

If your box is aluminum, you are not going to get a good ground plane.

If your box is metal you can bolt it to the bed.

Or you can go to just about any truck stop. Most have some kind of CB shop and buy a Mag Mount and screw one of your antennas to it and stick it on your roof.

Hate to say it but if it is not ugly than you don't talk!!

That is why I stress the wilson's. They are great antennas for normal CB use and they don't stand out.

 

Gotcha thanks. I will try and get to a radio shop over the next couple of days to get it done. Thanks for thhe help, I will probably have more questions later thanks again.

 

Good luck.

Let me know if you need anymore help.


73's Erik

 

I agree with every point but the ground. Your mag mount has no ground, and the mounting brackets for the twins are aluminum. Most OTR truck bodies and mirrows are also aluminum. Please correct me if I'm missing something.

 

Aluminum boxes is not going to give him as good as a ground plain as if he stuck a mag mount up on his roof.

Instaling the antennas on the box will work but not as good as if he put it on the roof. He will get more reflection which will result in lower transmit and recieve.

But it will work. Big trucks do it and it works because the mirror mounts are grounded to the doors. Which is a higher ground than a bed of a truck.

You would be surprised how many truckers spend big bucks on Big Radios and can't talk any farther than the next truck he see's. It is because the a lot of the new trucks have all fiberglass cabs and the antenna that is on the mirror is hung from a fiberglass cab.

I still think his bet bet is to return the firesticks or what ever he bought and go with a mag mount Wilson on his roof.

You always want to shoot for height!! If you do go with the box, take a separate ground from the box to the chassis. Make sure that the load for the antenna is above the cab of your truck.

 

You should probably double check that. The connector on every CB made is an SO-239, which is a 50 ohm connector. Trust me, as a licensed ham radio operator, you need to use 50 ohm cable unless you use a matching coil of some type.

 

what if I ran a ground wire from the antenna mount to the chassis? I also have four foot antennae sso they are quite a bit higher then the cab.

 

double checked it is rg-59 and they have pl-259 connectors

 

If you want to get a good signal go buy a 102" steelwhip with a ball mount and a spring. Mount it in the center of your tool box either directly or make you a elivated mount. Run a piece of copper wire from one of the mounting screws on the ball mount to the frame. Go to radio shack and buy some rg-8 and run a length of 3 like 12,15,18,21. You will have to cut the coax to length and mount ends. The last 5 trucks i have done like the the swr's were around 1.05:1 which is very good. Only problem with 102 is they are really tall when mounted.