CB radio trouble

[funkingonutz]

Alright, I have just installed my Cobra 25LTD CB radio, and i am having some problems:
1. With the truck turned on I get some crazy interference from all the trucks electronics, with the truck off and the CB on the static goes away.
2. I went all out and bought the best CB radio (my opinion) for the price, and then went out to the local Radio Shack and picked up a cheap $30 CB antenna.(i think thats my problem)
3. I went to go calibrate it today, like it says in the instruction manual (set the radio to CH. 20 hit the CAL. switch, tune the SWR dial until the needle in the S-meter is in the CAL location, then while still holding down the mic. button hit the SWR switch, and read the S-meter) well the S-meter is in the red, and the instructions say anything over 3(green) is bad. Also when i push the mic. button, the RX/TX LED lights up, and the ANT LED lights up red, and the S-meter pings way over to the red.
I think its because of where i have all the "extra" coaxle cable, its stuffed under my drivers seat, aren't you supposed to have the extra cable as straight as possible??

I am confused as hell and i need someones help on here......there is no CB shops around here, so i need your help on here so i can tune this thing!!

 

[Wicked_Sludge]

you did the opposite of what you should have done. a cheap CB with a quality antenna will out-perform an expensive radio with a cheap antenna any day. i would get yourself a GOOD base loaded antenna.

to help with electrical system noise, you can install a cheap RF filter on your power wires to your radio (radio shack sells them for $10-15). aside from that, ensure you have a clean, solid ground (attach it directly to a steel support under the dash, and sand the metal before you make the connection). make sure your power wire is also connected to a clean source. directly to the battery is best (but not always the cleanest).

your SWR readings: check to make sure the center electrode of the coax isnt grounded in any way. how does the cable attach to the antenna? screw-in fitting? extra coax is OK as long as there isnt miles of it. and never EVER coil up extra cable...always stuff it randomly out of the way.

also, where/how is the antenna mounted?

 

[funkingonutz]

you did the opposite of what you should have done. a cheap CB with a quality antenna will out-perform an expensive radio with a cheap antenna any day. i would get yourself a GOOD base loaded antenna.

to help with electrical system noise, you can install a cheap RF filter on your power wires to your radio (radio shack sells them for $10-15). aside from that, ensure you have a clean, solid ground (attach it directly to a steel support under the dash, and sand the metal before you make the connection). make sure your power wire is also connected to a clean source. directly to the battery is best (but not always the cleanest).

your SWR readings: check to make sure the center electrode of the coax isnt grounded in any way. how does the cable attach to the antenna? screw-in fitting? extra coax is OK as long as there isnt miles of it. and never EVER coil up extra cable...always stuff it randomly out of the way.

also, where/how is the antenna mounted?

The cable attaches to the antenna.....um its just in there?? the cable goes into the antenna, the cable is not a screw in. The cable screws into the back of the CB if thats what you mean. I did run the pos./neg. wires right to the battery. A good "base loaded" antenna?? explain please...im new to this. The one i have is a magmount, i have the antenna on the roof in the center, but towards the back near the third brakelight.
Stuffing the cable randomly out of the way, like where, under the carpet?

Now i can recieve messages but i cant send, if i try, the RX/TX lights up red and the ANT light turns on red

 

[Jorley]

A CB antenna has to be a certain length to work properly, I think it's 9'(has to do with wave length). So you don't have to use what's called a whip antenna(just a long piece of wire) antennas are "loaded". That means a shorter antenna has windings of wire to make up for the missing length. They can be "base loaded" or "center loaded". All this means is on the base loade antenna the windings are at the base of the antenna and the center loaded, they are at the center. The base loaded one will have a bugle at the bottom of the antenna. Most antennas are the base loaded kind.

About your TX problem,SWR stands for "Standing Wave Ratio". What that boils down to is amount of resistance to the TX signal that coax causes.(again has to with wave length). The lower the SWR the more power out.The coax needs to a certain length. The antenna you most likely came with the right length if "it's just in there". Make sure the cable has no kinks, or sharp bends and try to keep it away from itself( don't coil it up or let it cross itself). You're right about it needing to be as straight as possible. Also make sure nothing is grounding out the antenna. If you know someone with a CB, try yours with their antenna.

 

[funkingonutz]

what do you mean by something grounding out the antenna??

what are some good base loaded antennas?

are they going to cost an arm and a leg?

 

[funkingonutz]

what about the Wilson, Astatic or the K40 antennas?

 

[Jorley]

As Wicked said the center of the coax touching ground, or the antenna touching ground. Also being to close to a metal building or power lines could affect SWR. A high SWR means something is reflecting the TX signal back to itself. Since your antenna is a magnet mount try moving it to different place.

About the cost and quality of antennas, I'm not sure. You could Google "CB antennas" and compare the different brands.

 

[Jorley]

Here's a link to help explain SWR and such about your CB.
http://electronics.howstuffworks.com/question490.htm

 

[Ranger SVO]

First, with a DVM, make sure that you have no shorts in the antenna coax. With the meter make sure there is no Continuity between the center and the shield and ground.

Make sure that there is continuity from end to end

Do NOT cut the coax, its length must be a multiple of 3. Most store bought cables are 18 ft, but any multiple of three will work.

How to set SWR
Put your CB on channel 40, check your reading, and remember it
Put your CB on channel 1, check you reading.

If the reading on 40 is higher than on 1, shorten your antenna. Only shorten a little at a time. When the readings on 1 and 40 is the same (and in the green) the SWR is set correctly. If the opposite is true, get another antenna.

If they are the same and both are in the red, then you have a short or the antenna needs to be moved.

 

[Black'03LevelII]

what do you mean by something grounding out the antenna??

what are some good base loaded antennas?

are they going to cost an arm and a leg?

what about the Wilson, Astatic or the K40 antennas?

when I used to have my old car I had a 29LTD classic hooked up in it, used a wilson 1000 base with a 6ft whip. once I got the whip tuned in I could talk to the truck drivers at a service stop about 15 miles south of where I was at. Although I will admit that the radio was "teaked and peaked" but that is a whole nother topic (and technically is illegal).

oh and follow Ranger SVO's post and that should help ya out alot.

 

[reginald fairfield]

Although I will admit that the radio was "teaked and peaked" but that is a whole nother topic (and technically is illegal).

Peaked and tweaked may be illegal, but everyone that I know has it done anyway, so... Everyone knows the FCC don't care about CB's anymore...

 

[Black'03LevelII]

true true. I am cuurently looking into one of the "ham" radios that have been converted I guess (not sure howit's done or works) but those things are baaaad arse toys!

 

[funkingonutz]

yup ive found the problem....my coax cable was all wound up underneath my driver seat, so i straitened it out and got it away from itself, and went to calibrate it...it works!!! I was talking to guys that were on the interstate about 5 miles from were I was at, and a guy 2 towns over, about 6 miles.
(If anyone knows CT im in Enfield, and i was talking to a guy in Somers)

just got to remember to keep that cable away from itself, and not kinked in anyway.

I will pick up a better antenna sometime down the road, for now im pretty happy

 

[Black'03LevelII]

sweet glad ya got it working! cb's are a ton of fun, just remember be nice to the truckers and they will do the same to you.

 

[Jorley]

Glad you're up and TXing. CBs can be very useful things to have. Anoter tip is, early in the morning, just as the sun is rising, your range can be increased by "skip". What it means is that as the sun is rising the ionisphere(sp) is charged and the TX signal, instead of going into space, gets bounced back own to earth and back up, etc. The signal "skips" across the surface of the earth thereby increacing range. It doesn' last long but can be fun.