CB radio help

I found a cb in my garage and installed it. I can hear other people and my buddy but he can't hear me. Its just like a repeated tapping noise from his cb. We were like 2 foot away. Do we need to be farther? Do I need a new mic?

 

Yup, new mike and make sure all is grounded as it should be.

My old hot boxed Cobra and 5' of coax can talk 10+ miles with a 2' Firestick tuned properly. Have done it on multiple occasions. Firesticks talk to other Firesticks better. Do a group buy for your crowd and you guys will be able to chat alot easier.

 

I literally plugged all my junk in and it transmits and receives fine.

For anyone wondering:
I'm running a Cobra 19 with a 3' Firestik attached to a heavy duty spring, and an extra long mirror mount attached to the toolbox (There is a nylon lock washer thing in between the mirror mount and the spring, the washer came with one of these parts). 20' of coax wire from Radioshack.

Have never had any problems with it. Maybe you need the nylon washer rather than bare metal. But like I said, idk, I just plugged all my chit in and it worked.

 

What does the coax length effect? And what would be the best antenna for the price for a uniden pro 510xl. Would the 2' firestik be best. What does the length of the antenna effect and do I need to tune mine.

 

OK - with these symptoms, SOMETHING is seriously effed up. This isn't an antenna tuning issue or a choke (coiling) of your antenna cable, or the wrong length antenna cable or any of that mumbo jumbo.

SOMEBODY has a faulty radio, or a short in the coax cable, or an improperly grounded antenna, and it's either YOU or YOUR BUDDY.

You're inclined to think it's you because you just installed - but when was the last time your buddy successfully used his radio?

Do you know how to use a multi-meter to check continuity? Get a multi-meter. Let's do some diagnostics:

Unhook your antenna from your CB. There should be:

1. NO continuity (infinite resistance) between the signal (central conductor pin) on the antenna and the threaded conector that's conected to the outer braided shielding.

2. NO continuity between the signal and a known good ground on the vehicle frame

3. GOOD continuity (very low resistance) between the threaded connector on the cable and a known good ground point on the vehicle.

If any of those is bad - you've got a faulty antenna installation. You either installed the antenna wrong at the mount point (most likely) or you pinched the coax and damaged it while you were running it. (Coax is fairly delicate - and damaging it is relatively easy to do when you have to pull it through tight routing spots, or if you bend it around too tight a corner.

Test your antenna - AND your friend's.

One more thing to check - is your radio electrically grounded? You've got power on the red wire - is the black wire solidly connected to a good ground? If the power ground is faulty, then power will flow through the antenna shielding back to vehicle ground. That'll ruin your signal also.

Check the microphone connection and cable.

If all that proves out OK, someone's probably got a faulty radio. I know of no simple way to test a radio other than using it. But you can try raising other folks besides your buddy by hailing on Ch 19 for a radio check while near to a major heavily trafficed interstate. Someone is pretty much guaranteed to be nearby with a good radio.

(If you just monitor at your house - you're likely to pick up folks DX (long distance) transmitting from far-far-away with wildly overpowered rigs hooked up to gigantic antennas. It doesn't mean *anything* if you hail them back and that don't raise a response.)

Once you get past that into the "finer points" of antenna turning - as far as antenna tuning goes - you said you tuned to 2.5 SWR - on what channel? I retuned my CB with a new antenna and new cable last weekend.

I got SWR 2.5 on Ch 1, SWR 1.3 on Ch 20, and SWR 2.7 on Ch 40. As you can see - there's a wide variation in the SWR across the CB spectrum. What you want is for your SWR to be roughly the same between Ch 1 and Ch 40; that's the best tuning for the band as a whole.

As far as the 18' "magic length" coax goes - that's because 18' is a half wavelength of a 27 mhz frequency wave. But that doesn't matter - you want your ANTENNA to be a meaningful fraction of that (e.g. 1/4 wave) connected to a good ground plane.

So why is there so much annecdotal evidence that an 18' cable lenght is good? I have two hypothesis:

1. As I mentioned above, COAX is fragile and easily damaged. So if you replace a cable with a new 18' one - likely you're replacing a damaged cable with a good one. But you think: "Wow! That 18' length was just the ticket!"

2. A CB antenna (or most any vehicle mount antenna) is a ground-plane dipole antenna. That means the part you look at is just half the antenna - and the vehicle body/chassis forms the other half. But if it's not properly grounded, or it's attached to a fiberglass bed, or a tiny piece of steel like a tire frame mount, etc... etc... that's an insufficient ground plane and the shielded coax has to form the bottom half of the dipole antenna. And if the coax has to form half the dipole, then, well duh, it works better if it's a half a wavelength.

But - if you've installed properly to a good ground plane, the fact that your cable is too long means you're more likely to

1. damage it by stuffing the extra out of the way or
2. create a "choke" by coiling it up and tying it off with zip ties.

And either of those make your antenna worse, not better. My most recent install was "just right" with only a 9' antenna cable.

Hope this helps.

 

A 2' antenna is awfully short unless you're mounting it to the roof of the cab. And those firestick fiberglass antennas are awfully stiff for a roof mount. The roof of our trucks is just thin steel. You don't want to hit a branch and have your oh-so-sturdy antenna rip out your antenna mount.

But you want the top of the antenna to stick up above the cab. So if you're mounting it to the bed - a 3' length is good. If you're mounting to the bumper, a 4' length is good.

 

Use the same diagnostics I described in a post above.

 

Were do you guys run the coax cable to the cab at?

 

Trace your parking brake cable. Very close to where it enters the cab, there's a round rubber plug that's just under the middle of the bench seat.

I made a small incision in the center trunk carpet to access that location so I could run the cable without pushing and pulling the hell out of it. But the coax actually runs under the carpet and isn't visible once the job is buttoned up and put away.

 

I'm using the little willy by Wilson and it transmits loud and clear. Great product.

 

Post a picture of how your antenna is mounted and one of where the mount is attached to. Sounds like a simple grounding issue. OR the coax connections weren't soldered properly. One of the two.

 

Its a magnet on the top of cab. I tried it today and cant hear it. I have to turn it all the way up to get the faintest sounds. It was just working yesterday.

 

Figured it out. Just need to wiggle the mic jack and cord around. It probably needs a new one. Got it routed under the cab and through a plug under the drivers side carpet right above the frame rail. Thanks bjmoose!

 

glad to help.

 

That's where my 2' was,,rail of bed pass side. Probably about 8-9" in from the outside edge of the bed. The top of the Stick was about 3"-4" above cab on a very short custom 3 coil spring and bracket. Coax routed thru a cab grommet into the tire tool storage area then under carpet to the area by the cupholder for the Cb mount. Lost a slide out cupholder due to the mount. But the Cb has rode side saddle to the cupholders for years. Added a between seats cupholder,,for the cold beverages.

You can snap them off mounted there,,and dent your cab. Seen it happen. Just gotta use your head a bit when wheeling in brush. Put it there to protect it more and to not look so RC truck mounted up on the front fender.

A buddy from work has some hotrodded hand held 40 channels. Big 6S LiPo packs,DC for recharge. Miles away and it sounds like someone is standing right there. Just never let them meet powered up and then dead key. Ear peeling screech at 1/4 dial!. I am talking decibel warble that will make you see colors!.

 

finally got it figured out!

after reading what bjmoose wrote, i went out and uncoiled the extra coax and spread it behind rear seat, added a 90* adapter to the back of the unit to prevent kinking when stuffed in the ashtray, and even swapped to a 3' fiberglass antenna.

met up with my buddy again to try it out again and the same thing happened! I came thru clear on his radio, but i got the same screech/siren sound when he keyed his mic. so i told him to try switching out mic's and sure enough it went away. wasn't even me the whole time lol

my next question is now this, my 3' antenna is a fixed length francis. swr reads around 1.2 on ch.1 and about 2.5 on ch.40. would adding a spring help get the swr reading better?

also, with my whip antenna, i can't seem to get the swr under 2?? i can get both channels to match up close, but just can't get the reading any lower. any fixes for this? I'm not looking to pick up people across the country, but would like to have a decent setup. i was thinking of using the whip when offroading so breaking wouldn't be an issue, and the fiberglass for normal conditions (unless a spring helps with swr) then id run it all the time

 

No. With the SWR being higher on the higher channel, your antenna is electrically long. Adding a spring would just make it longer.

If it's not a tunable antenna - I'd say call it good. You've got 1.2 on your best channel and 2.5 on your worst channel. That's pretty darn good, actually.

 

How long is the whip?

 

Where do you guys attach the ground under the hood? My marine band radio is grounded to the body next to the battery but I'm not sure if this is correct or not.

 

Connecting it directly to the battery is your best option.