cb radio help - AR15.COM

Posted: 10/22/2004 9:57:04 PM EDT

I installed a Cobra 75 CB radio in my Vette and I have a custom mounted antenna inside the car. It sits right behind the seats in the middle. My SWR is sitting around 1.2-1.3 and I am getting out talking with no problem. I am powered through the 12 volt cig lighter in my center console.

The problem is when I key up and talk in the mic, my little light on the center console that indicates the passenger air bag is off lights up. It lights up according to how loud I talk, in other words, if I talk quiet, it is very dim and if I talk loud it gets bright. So it seems like there is some kind of bleedover. Anyway I can fix this? Also when I hit my power windows I can hear it through the cb radio, same with the power seats.

What should I look for to solve this?

Posted: 10/22/2004 10:04:10 PM EDT

[#1]

Sounds like you need to find a good ground.

Posted: 10/22/2004 10:05:24 PM EDT

[#2]

Get a Ham radio in the 2 meter range. But get a license first though...............

Posted: 10/22/2004 10:13:28 PM EDT

[#3]

I would guess antenna radiation is lighting up the light on your console if its not a bad ground, relocate the antenna to outside the car and see if the problem continues. A long time ago when I used to mess with CBs we would amplify our radios and actually turn on street lights by transmitting under them with the right antenna. You'll get out better anyways.

For your other problem, you might want to power your CB by wiring straight from the battery terminals; that might take care of the electronic noise and a poor ground. Otherwise I believe there is a noise filter you can buy at Radio Shack. Good luck.

Edited fer speeling.

Posted: 10/22/2004 10:16:25 PM EDT

[#4]

I imagine that you will have trouble getting a CB to work very well in a Corvette, due to the lack of meatl in it's construction, it is hard to ground to fiberglass, and Carbon Fiber, and without good grounds Radio communications devices are very unreliable.

Posted: 10/22/2004 10:30:09 PM EDT

[#5]

Run the power straight to the battery.

Posted: 10/22/2004 10:59:20 PM EDT

[#6]

Quoted:
I would guess antenna radiation is lighting up the light on your console if its not a bad ground, relocate the antenna to outside the car and see if the problem continues. A long time ago when I used to mess with CBs we would amplify our radios and actually turn on street lights by transmitting under them with the right antenna. You'll get out better anyways.

For your other problem, you might want to power your CB by wiring straight from the battery terminals; that might take care of the electronic noise and a poor ground. Otherwise I believe there is a noise filter you can buy at Radio Shack. Good luck.

Edited fer speeling.

Ok, I think that is what it is because I have a good ground, I know i do. I didn't have a good ground at first and my SWR was right at 3.0 across all of the channels. I drilled a small hole in the cross bar that runs behind the seats and used a self tapping screw and grounded the antenna to that. The SWR dropped right after I did that, so I know have ground.

Do you think it will damage anything in the car if that antenna radiation keeps lighting up that light? I was really trying to avoid an outside antenna but if that is the only way to go, I guess it's the only way to go.

Posted: 10/22/2004 11:03:34 PM EDT

[#7]

I wouldn't think that it would do any real damage, vehicle electrical systems are built with the assumption that the power is going to be nasty and fluctuate wildly. Even with the Ant grounded the radio needs to be grounded as well, if possible to the same ground point as the ANT. THe negative side of the Cigar lighter is not always a great ground, especially in a car that does not have all that much steel, does your car have a steel frame? if so that would be a good ground, much better than sheet metal.

Posted: 10/22/2004 11:06:58 PM EDT

[#8]

Quoted:
I wouldn't think that it would do any real damage, vehicle electrical systems are built with the assumption that the power is going to be nasty and fluctuate wildly. Even with the Ant grounded the radio needs to be grounded as well, if possible to the same ground point as the ANT. THe negative side of the Cigar lighter is not always a great ground, especially in a car that does not have all that much steel, does your car have a steel frame? if so that would be a good ground, much better than sheet metal.

Yes, the frame is sheet metal and you are correct, the CB radio is grounded through the cigarette lighter.

Can I just splice into the ground to the radio and run a jumper to where the antenna is grounded?

Posted: 10/22/2004 11:12:47 PM EDT

[#9]

It may work well that way, I would try that first, before you start drilling more holes anyway. A wire directly to teh battery for the power would also be a good idea, it still leaves the possibility of ALT whine, but will not be as likely to interfer with other electronics in the vehicle. If your car is a computer controled vehicle to much of that type radiation could corrupt the firmware in the computer, I am not saying that it is likely to happen, it isn't, but it is possible.

Posted: 10/22/2004 11:21:16 PM EDT

[#10]

Thats cool, I'll try that.

The frustrating thing is the electronic interference isn't really that bad, only noticeable when operation power windows/seats. What sucks is the radio is working great and has a very good match with the antenna. BUT, that damn light comes on when I key up and talk.

Posted: 10/22/2004 11:22:48 PM EDT

[#11]

what is happening with the airbag light is rf feedback inside the car cause the antena is inside . If you can try and find some copper mesh screen and build a cage to put around your computer and to get a ground you can ground it to your seat bolt ( if you want to do it that way)or you can run the power and ground wire into the engine compartment hook up the power wire to your power block if your car has one and hook the ground to a fender bolt if it is metal on the opposite side from the alternator(so you don't get that annoying alternator whine )

Posted: 10/23/2004 12:06:17 AM EDT

[#12]

I'm sending the internal set up back if the guy lets me and I am going to buy one of these.

www.ecklers.com/product.asp?pf%5Fid=42678&dept%5Fid=1340&mscssid=4GVRMC77RC469NGPPUBQBQRXNJPQ3GUC

Posted: 10/23/2004 12:10:35 AM EDT

[#13]

I have a Cobra I need to install in my Lightning.

Posted: 10/23/2004 12:15:58 AM EDT

[#14]

Quoted:
I have a Cobra I need to install in my Lightning.

Don't rub it in you dog. Installing a cb in a Lightning would be a piece of cake after what I have been through.

Go get a damn Lil Will, stick it on the roof, plug your radio into the cigarette lighter, tune your SWR and you are good to go. You think your so special with all that wonderful ground plane don't you???

Posted: 10/23/2004 12:20:06 AM EDT

[#15]

Sounds like VSWR is not seriously bad for a Vett (no flat sheet-metal so no "ground plane" for the antenna to use). As for the light, try stringing a length of wire to the bass part of a flashlight bulb but don't connect the other end of the wire to anything. After it's dark enough to see, hold the bulb up near the end of your antenna & just let the wire dangle, key your mike, and say "Shazam" with some decent volume. Used to work anyway - RF from the Tx was enough to light the bulb, especially with a 100W "kicker" behind the seat.

Posted: 10/23/2004 12:22:40 AM EDT

[#16]

Quoted:
Quoted:
I have a Cobra I need to install in my Lightning.

Don't rub it in you dog. Installing a cb in a Lightning would be a piece of cake after what I have been through.

Go get a damn Lil Will, stick it on the roof, plug your radio into the cigarette lighter, tune your SWR and you are good to go. You think your so special with all that wonderful ground plane don't you???

I got a really nice one that hooks into the wires under the dash. Its huge, but it has just about every feature you can put on one of those things. I think I'll see if the antenna can be mounted to the frame or inside the bed rails or something, to hide it.

Posted: 10/23/2004 12:24:56 AM EDT

[#17]

Quoted:
Quoted:
Quoted:
I have a Cobra I need to install in my Lightning.

Don't rub it in you dog. Installing a cb in a Lightning would be a piece of cake after what I have been through.

Go get a damn Lil Will, stick it on the roof, plug your radio into the cigarette lighter, tune your SWR and you are good to go. You think your so special with all that wonderful ground plane don't you???

I got a really nice one that hooks into the wires under the dash. Its huge, but it has just about every feature you can put on one of those things. I think I'll see if the antenna can be mounted to the frame or inside the bed rails or something, to hide it.

You don't want to hide the antenna, you want at least 40-50 percent of the antenna above your roof line.

Posted: 10/23/2004 12:26:35 AM EDT

[#18]

Quoted:
Sounds like VSWR is not seriously bad for a Vett (no flat sheet-metal so no "ground plane" for the antenna to use). As for the light, try stringing a length of wire to the bass part of a flashlight bulb but don't connect the other end of the wire to anything. After it's dark enough to see, hold the bulb up near the end of your antenna & just let the wire dangle, key your mike, and say "Shazam" with some decent volume. Used to work anyway - RF from the Tx was enough to light the bulb, especially with a 100W "kicker" behind the seat.

Yea, talk about kickers, my buddy hooked up his 250 watt linear to my car "just to see" and it not only lit up the air bag light but it lit up the climate control lights too on the dash. That was just by keying up, not even talking. I immeadiately took it out of the car.

Posted: 10/23/2004 12:27:21 AM EDT

[#19]

Quoted:
You don't want to hide the antenna, you want at least 40-50 percent of the antenna above your roof line.

With CB being AM you want all the height you can get on the Antenna, otherwise you will get piss poor Tx and Rx. You can always get an aerial that has a quick release so you can remove it when you are not using the radio.

Posted: 10/23/2004 1:33:05 AM EDT

[#20]

Uh-oh. Just looked at that link lvgunner777 and those bayonet connectors on the base of the antenna were somewhat hit-or-miss IIRC. I happened to have good luck but some of my old buddies didn't. We came to the conclusion that mounting position (wind) combined with the inherent necessary slop was probably the culprit - some guys had a bit of trouble with momentary break-up. Never did figure it out for sure though so YMMV. Not too expensive either so it could be worth a try. It indeed would get the antenna further away from the dash and that might make it worth the try no matter what.

Posted: 10/23/2004 1:50:30 AM EDT

[#21]

Not that it helps your problerm but here is my bad boy:
Throwing 30watts out bone stock!

Posted: 10/23/2004 1:58:07 AM EDT

[#22]

dang m4 all I got is a little cobra 25,cobra 29,pres. washinton base and a couple other things

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