I would swear I read in a couple of posts earlier values of .5. I just wanted to clarify so people don't go crazy trying to achieve impossible values

 

Under 2:1 is generally fine. Sure, the lower the better, but don't stress over it too much unless it's above 2:1.

Edit: As noted, a 2.5 isn't likely to hurt anything with CB's low power.

 

Stop drilling holes in things. If your antenna mount is bolted to the tailgate, you're done. You probably need to bond the tailgate to the chassis.

Do NOT use solid wire. The ground needs to be flexible, as you're going to open your tailgate from time to time (presumably) and solid wire will work-harden and fail. Use braid, like this:



Solid wire is also bad for RF grounding purposes due to skin effect. There is exponentially more skin in braid than on a solid piece of wire.

Ground-strap braid can be had from a variety of sources. I get mine from old coax. I strip off the outer insulation and pull the braid off. Boom. Done.

For more on SWR and other RF issues, see the JK Forums thread I started on the subject here.

 

I was checking out your other posts, but couldn't find the one for antenna grounding. (probably my search error). Thank you for the info!

 

There's a link in the text you quoted.

 

Thanks for the good info here, it made my CB install/tuning go smoothly. I'm taking + and - directly from the battery and am experiencing ignition noise. I've got an ANL which mitigates most of the noise when receiving but I'm concerned that the noise is being broadcast when I transmit.

Should I change to a chassis ground? My understanding is that direct connection is the best. Thoughts? Thanks.

 

Direct connection should do away with ignition noise. Hm. I doubt changing to a chassis ground will help.

Are you talking alternator whine, or some other sort of noise?

Properly bonding body pieces are one way to mitigate noise.

So is thinking about your coaxial feedline. Remember, maximizing your antenna system for transmit also maximizes reception! Not only is vehicle noise RF - which your antenna system is designed to pick up - the coaxial feedline is part of the antenna system. There are a couple of ways to mitigate noise coming in from the coax. First is routing the coax perpendicular to vehicle wiring harnesses. The con to that is it can require a lot longer feedline than you have already. The second is adding ferrite choke beads. See here for details on ferrite beads.

Hope that helps a bit!

 

Thanks for the reply. It's not so much an alt whine as a low volume clicking/buzz that increases in frequency as I increase speed. It's not terrible, but it's there. Coax is routed through tailgate, through passenger rollbar padding and finally across the top of the windshield, coming out at the footman loop.

My SWR is between 1.5 and 1.8 (ch. 1 and 40 respectively). Do you think that type of noise would be present when I transmit?

 

Probably not during transmission, but there's no way to be certain without reception tests. Get together with a buddy and try it out.

Your description sounds to me like a combination of ignition and fuel-injector noise. Try clip-on ferrites on the ignition-coil leads to start. Radio Shack sell them. That'll help with ignition noise, maybe.

Edited to add: Give your setup as installed a try first, using the gear as you intend, i.e., if you installed it to communicate on trail rides, give it a go. If the noise is so bad you can't do what you want, then it's time to address it. It may just happen that signals in your intended use are so strong that the noise isn't really interfering with reliable communications, which means it ain't broke.

If that fails, and if ferrite cores don't work, come use 21st century technology and use FRS/GMRS instead of CB. They're MUCH more useful for off-road pursuits than CB.

 

Thanks for all that, Bob. I'm on and off road and intend to try it all out and see what I've got before making further changes. Cheers!