CB Radio Information and Installation

Loss is measured in 100' length @100 MHz there is very little difference between 9913 and RG8X except one is about 1/4" the the other is about 1/2" me I'll go with something practical the loss in the coax run in a truck is very close to forget it. It's not worth worrying about. Running it up a 200' Tower you might want to reevaluate. LMR400 is good cable low loss but it's not something you would want to run through your truck it's too damn stiff and thick much less trying to terminate the ends. Losses goes up with frequency at 11 meters the loss is very low to begin with RG8X is a very good choice for something mobile.

 

Coiled coax is often used as a common mode choke.

 

4' firestik2. + 18' & cable isn't looped. I messed with the adjustment screw and was able to get it up to about 1.1 yea to go up, I'm thinking the external SWR meter is broke, I have no problem and just trying too hard. Built in swr seems to work fine.

 

Usually a faulty meter will just always read 1 with no movement at all, or it will move all the way to max when you key the mic.

You may just have great SWR. Mine reads about 1.2 and 1.1 from 1 to 40. So low is good, if you are transmitting, and others can copy, I wouldn't worry about it.

Too bad you're farther away or we could use my SWR meter to see if you get the same results.

 

Yes, I know. That's why I said anything other than RG8X isn't practical in mobile applications. Besides being rather thick, it doesn't flex very well.

 

That's exactly why I'm agreeing with you! The loss in a mobile installation is a lot to do about nothing.

 

Okay...I misunderstood your post.

I need to get started putting my Icom IC-2820 in my truck. I've got an interview for an Emergency Preparedness Planner for the Sheriff's Office next week. I miss being in public safety so it's time to go back. If I get the position I'm going to get myself an Icom IC-7000 and put that in the truck too. Then I'll be set. I just installed a Kenwood DNN-990HD navigation unit that uses my cell phone as a hotspot so I can get information from just about anywhere.

 

Added a part about quality of radios that are now being manufactured in China. Thanks CircuitBreaker, I never tied it together until you mentioned something about it.

 

Outstanding write-up, OP. I actually referenced this, along with the Firestik documentation while setting up and tuning. Once you tune the first channel, it's pretty simple...unless you're over 2 or so.

Your post is pretty much the Cliffs Notes version of everything else that's out there!

 

Tune it on 20 you can't change what it will be on the other channels so tune it in the middle then it will be good as it gets across the band.

 

It is just easier to know which way you need to adjust the antenna by doing the 1/40 method. If it's higher on 40 than it is on 1, you need to shorten then antenna; if 40 is lower, then you need to raise it. (The little adjustable tip if it's equipped)

But yes, once you get those evened out, it should be pretty low right in the middle.

 

Yeah, I just took SWR readings on ch 1, then 40. I read slightly short, and it took me 2 adjustments to equalize the channels. They're now sitting at 1.5:1. If I would have read only at channels 19/20, I wouldn't know if the antenna was long or short.

Firestik desrcibes the SWR "dip" due to the bandwidth differentials here: http://www.firestik.com/Tech_Docs/swr-intro.htm.

All that said, does anyone believe I should improve the ground (larger braided ground to improve the SWR)...or just be content with 1.5:1?

 

1.5 and 1 is great. I would be content.

Additionally, I think you don't need a very big gauge of wire for the ground for vehicle applications.

Unfortunately, vehicles never produce a terrific ground. So just make sure it's as close to the frame as you can get it without worrying about it snagging on stuff as you drive.

 

Thanks...I'll just be happy with it, then!

 

That is a good method but the bottom line once you have found out where you were going with it the center freq is going to be the best spot to match the antenna. With a $20 SWR meter and 4 watts I would not lose sleep over any thing under 2:1 swr. If your mount is grounded to the truck (bolts etc.) adding a welding cable from the mount to the frame will not improve any thing.

 

Thanks! I slept well last night...

 

The downside to putting the antenna down low is that ground losses increase, decreasing antenna efficiency. Is it enough to worry about? Probably not at 27 MHz. It would be more of an issue down around 7 or 3.5 MHz...certainly not going to go that low with a CB though.

 

The ground point, not the antenna. Poor choice of words on my part.

 

Years ago the old boats were poorly bonded there was not much attempt to tie any thing together. They required a lot of effort to ground things like hoods, doors, exhaust, frames bumpers you name it and the old habits die hard. The newer stuff with all the electronics a greater effort to reduce noise and provide proper grounding was put in place. Have a look at your battery ground for instance the first place it is frame/body grounded is less then 4" from the battery. If you have to add a wire from your mount to some thing else tells me your mount is not bonded to the truck. Adding a wire may well compound your problems if it is not properly grounded depending on it's length it may become an antenna and a very poor one at that! No matter what you do a vehicle is a very poor ground plane but a CB antenna with radials at the base would never fit in a garage.