Where should a CB radio be grounded to?

Chris

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I have heard some say that the ground wire can be run directly to the negative battery terminal, and others say that’s a bad idea and that it should be run to a chassis ground.

My positive is going directly the the battery with an inline fuse.
 
Chris, honestly they should be “close to” the same electrically. You’re difference of potential between the 2 is the resistance of the metal between the ground spot and the negative terminal. I’d prefer directly to the battery but would not advise against any other proper ground.
 
Chris, honestly they should be “close to” the same electrically. You’re difference of potential between the 2 is the resistance of the metal between the ground spot and the negative terminal. I’d prefer directly to the battery but would not advise against any other proper ground.

Okay, I've got it currently grounded to the battery right now which I figured would be fine.

Just wanted to make sure though since I'd heard differing opinions.
 
That would be my preference. Yes m sure it will work great! What radio/antenna are you running?
 
That would be my preference. Yes m sure it will work great! What radio/antenna are you running?

I've got a Uniden PRO520XL and a Firestik 3' antenna.

Just got it all setup tonight, so tomorrow I need to see if I can tune it and get it working. Right now when you turn it on there is no static or anything, so I'm assuming something isn't setup correctly. The unit powers on and seems to work just fine, but again, no static at all.
 
I think you’re right. There’s a bunch of little things that could be wrong, but you’re pretty sharp. I have seen more than one factory coax terminated incorrectly, so I’d poked around with a multimeter. Verify continuity pin from one side to pin on the other and do the same with the shield. I’d also make sure the pin isn’t shorted to the shield and double check my antenna ground.
 
I think you’re right. There’s a bunch of little things that could be wrong, but you’re pretty sharp. I have seen more than one factory coax terminated incorrectly, so I’d poked around with a multimeter. Verify continuity pin from one side to pin on the other and do the same with the shield. I’d also make sure the pin isn’t shorted to the shield and double check my antenna ground.

Yep, I'll figure it out tomorrow so wish me luck (y)
 
@Chris

The convention in the ham world is to run the positive and negative wires straight to the battery. Electrically it doesn't really matter if the ground is to the body/frame close to the radio or to the battery, but the theories are that grounding directly to the battery prevents the possibility of ground loops can cause radio interference, a ground wire directly to the battery has less resistance than grounding through body and frame, and that grounding directly to the battery will result in the battery buffering or "absorbing" interference that would otherwise be picked up by the radio.

Whether or not any of these theories are valid and to what degree has never interested me much. I have always grounded directly to the battery because that is what I was taught to do


Some (perhaps many) hams advocate fusing both the positive and negative leads rather than just the positive. The primary rationale is to protect expensive radio equipment from the possibility of a faulty ground elsewhere in the vehicle causing excessive current to flow in the negative lead to the radio. However, that rationale isn't particularly compelling if one is installing a CB radio that costs only $60.

This article, written by an actual expert, will teach you more about wiring mobile radios that you ever wanted to know:

http://www.k0bg.com/wiring.html
 
I'm going to say the exact opposite - ground it to the chassis with a wire braid as short as possible. Just make sure the connections are good - use star washers. I grounded mine at the stud that held on the stock radio back brace, but mine's in-dash. There is NO WAY a wire running to the battery has lower impedance than 3,500 pounds of steel, not from a DC perspective and certainly NOT from an RF perspective. That long ground wire is a theoretical antenna and is HIGHER impedance (especially with RF), unless, of course, you run 4-0 - then it might be about the same as the chassis. But a bit of impedance isn't going to hurt anything DC-wise (you're not pulling enough power to matter) but you don't need to add an antenna to the ground side of the radio - its bad enough that there's one on the positive side!

Yes, copper has lower resistance than steel - but there is a LOT MORE steel!

And then run an in-line power filter to filter out the ignition noise that positive lead "antenna" picked up on its way to the radio. I have the same radio - and this setup works GREAT!

Now this is all theory - in practice it may not matter much. Oh, and use that wire braid to ground the radio chassis as well. I looped the negative wire around to the side where the mounting bracket screws on, and ran the braid from there (chassis is floating as shipped to enable the radio to install in positive ground vehicles without issue - might as well turn it into a shield).
 
All the theory is why I keep it simple. At the low power and performance of a CB it really is preference. The antenna is what matters and that subject is a can of worms! Just mount it high with a good ground and tune that puppy.
 
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I'm about to wire mine, so thought I'd revive this and see how things worked out for @Chris .

Also, @Zorba , can you say more about the in-line filter? Or recommend one that I should install when I wire my CB?
 
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Great, thanks.

So, if I have a Uniden 520 (like so many on this forum), will my ANL switch do the same thing this does? Is this basically a noise filter for radios with no ANL feature?
Yes/no/maybe. I still had noise even with the ANL engaged, although it was pretty low and completely tolerable. The filter brought the level down to better than the ANL. With them both, I have no noise at all unless I crank the RF gain to max, then I get a tiny bit. The filter gets rid of power line noise (only), the ANL gets rid of noise from everywhere. I still engage it at times in traffic when I'm next to someone who is emitting sparkplug noise or when power line hash gets annoying.
 
Yes/no/maybe. I still had noise even with the ANL engaged, although it was pretty low and completely tolerable. The filter brought the level down to better than the ANL. With them both, I have no noise at all unless I crank the RF gain to max, then I get a tiny bit. The filter gets rid of power line noise (only), the ANL gets rid of noise from everywhere. I still engage it at times in traffic when I'm next to someone who is emitting sparkplug noise or when power line hash gets annoying.
Got it, thanks! I'll see how mine does without one first, and will save your link if I end up wanting one.

Maybe a little-known perk of four-bangers will be that they don't produce as much noise. :)
 
Got it, thanks! I'll see how mine does without one first, and will save your link if I end up wanting one.

Maybe a little-known perk of four-bangers will be that they don't produce as much noise. :)
Yea, definitely see whatcha got before worrying about it. Even without, mine wasn't particularly bad, but I figured it could be improved so I did.