CB Tuning

You'll have reception/transmission issues and could possibly damage your receiver (i.e. Burn it up.) The most common issue is a bad ground at the antenna.  So I would start looking there.  Other common  issues are your antenna is to tall or to short.  That maybe why your tire carrier had it mounted so high I'm just guessing. I also have an SWR meter if you need it. Let's us know how it works out.

I'll move my antenna back up to the tire mount and see if that helps.

Dale has the number to a cb guru in orangeville. Works from home.

I changed the antenna back to the tire carrier mount and moved my ground wire from the chassis to directly hooked to the battery. I am now getting a 2.0 on both Ch 1 and Ch 40. I'd really like to get it down to 1.5. I'll play with it more tomorrow. Maybe try a different antenna and try to clean off some of the powder coating on the mount.

The powder coating shouldn't matter TOO much... What kind of antenna did you get? Fiberglass? Whip?

2.0:1 will give you issues. For CB, you really want that below 1.5:1 in order to have much functionality.

It sounds like you have everything setup just fine... you are going to need to tune the antenna. You just need to figure out if it is 2:1 LONG or 2:1 Short.... usually most CB antennas will come LONG and they will need to be tuned shorter. The manufacturers do this so that they dont end up "short" once your system is setup. Because once they are short, there is not much you can do. Check the instructions that came with the antenna and see if they mention anything about "tuning" or "trimming" the antenna.

GOod luck!

Thanks Tyler. It's a Firestick fiberglass antenna. I will research how to shorten/lengthen it.

JohnDF said Thanks Tyler. It's a Firestick fiberglass antenna. I will research how to shorten/lengthen it.  

If you take the rubber cap off of the tip there should be an adjustable tip. http://www.firestik.com/Tech_Docs/Setting_SWR.htm

Success!!! I was able to get Ch1 and Ch40 down to a 1.4 reading, and Ch19 down to a 1.2.

Two things were wrong (I think).

1. I had the poly washer below the mount instead of on top of the mount.

2. I pulled the base to attach the meter and left it "floating" instead of grounded.

So, I moved the poly washer and grounded the base; Problem solved.

Jeff_R said

If you take the rubber cap off of the tip there should be an adjustable tip.  

Corect. I used the tune-able tip to get Ch1 and Ch40 at the same readings.

FYI - The "CB guru" dude's name is Doug in Fair Oaks. He works by appointment only. If you need CB help you can call him at (916) 988-4589.

buckallred said FYI - The "CB guru" dude's name is Doug in Fair Oaks. He works by appointment only. If you need CB help you can call him at (916) 988-4589.  

Awesome.

Nice! 1.2:1 and 1.4:1 is awesome. You wont get much better than that with CB.

Because my antenna is mounted so high, it won't allow me to pull the Jeep into the garage. I figured it was going to be a pain to break out the wrenches every time I got back home for a run. So, I ordered a quick release mount from Firestick. I installed it today, hooked up my meter again, and all my reading had spiked to way past red line. I immediately pulled it off. Why would a mount, made by a respectable company, cause such drastic spikes? Is there a fix for it?

Do a whip antenna and secure it to the front bumper and your done good to go

JohnDF said Because my antenna is mounted so high, it won't allow me to pull the Jeep into the garage. I figured it was going to be a pain to break out the wrenches every time I got back home for a run. So, I ordered a quick release mount from Firestick. I installed it today, hooked up my meter again, and all my reading had spiked to way past red line. I immediately pulled it off. Why would a mount, made by a respectable company, cause such drastic spikes? Is there a fix for it?  

Essentially, everything the antenna is attached to, is your electrical circuit that, when pulsing at a certain frequency (in this case, 27.400mhz, and around there for the CB channels), creates RF which is the electrical carrier signal of your voice that travels through the air.

In order for an antenna to work, it needs to measure a minimum of 1/4 of the wavelength of the frequency you are trying to transmit on, and in 1/4 wave increments, i.e. 1/4, 1/2, or 5/8, or full length (the 5/8 is the only one that breaks that rule). For CB, that magic number is roughly 102" (hence why people have 102" steel whip antennas for offroading).

Firestick attains the 1/4 wavelength by adding in loading coils, and wrapping the transmission wire around a fiberglass pole to get more transmission line in a shorter length. This is fine doing it, but the more you "coil" the wire, the more narrow banded the antenna becomes. This is one of the major reasons i am against CB. Because it requires such a long antenna to work, it is much harder to get a shorter antenna to work and tends to cause headaches.

The entire antenna system that actually transmits the RF starts where you screw in your coax line into your antenna/mount. So, in your case, by changing the mount, you have changed how your antenna radiates your RF signal (aka changed the length of the antenna). My guess is that the new mount is bigger and heftier and more material than your original mount. So, you PROBABLY just made your antenna electrically longer by adding the mount. If you trim the antenna down again (following the instructions to shorten/trim your firestick), your SWR should come back down to reasonable levels. I dont think there is really any way you physically "shortened" your antenna by adding the mount, so trimming like you did before, SHOULD do the trick. If you have a full on SWR meter or antenna analyzer, you should be able to find out if your antenna is "too long" or "too short", and then modify the antenna accordingly.

Good luck! Lemme know how it turns out!

Makes sense, I did not know about the 102" rule. So I guess in theory, if my new mount added 3" to the antenna, then I'd have to trim 3" off the antenna. Thank you.

JohnDF said Makes sense, I did not know about the 102" rule. So I guess in theory, if my new mount added 3" to the antenna, then I'd have to trim 3" off the antenna. Thank you.  

In theory, roughly, yes. Start at 1", then test it, do another 1", then test, etc... once you get down to 2:1, do .5" increments.

That should get you pretty close.

Thanks. I'm trying to decide if I want to start stripping wire off my antenna or just get rid of the quick disconnect mount.

At this point it might just be easier to shout at people through the window.

So, I put the original mount back on and the readings dropped back down. Then I changed doors to my [abs] half doors and my readings spiked again. I'm guessing less metal/ less ground plane? So, I'm guessing my only option is to start cutting off wire from my antenna?

JohnDF said At this point it might just be easier to shout at people through the window. So, I put the original mount back on and the readings dropped back down. Then I changed doors to my [abs] half doors and my readings spiked again. I'm guessing less metal/ less ground plane? So, I'm guessing my only option is to start cutting off wire from my antenna?  

Ya, you want to make sure you have your antenna grounded to the chassis... taggart can be as simple as adding a ground strap from the quick disconnect mount to the tire carrier you have.

Interesting. I have the quick disconnect also. Now I want to go double check my readings. 🤔

I ordered a ground strap.

I had ok SWR readings but terrible signal until i scraped off the powder coat to ground the antenna.  After that, near 1.2-1.1 on both ends.  I know the firestick is designed to be paired with a 3" spring so maybe remove the spring and put the quick-release in place of it.  Not sure how the doors would be that much of an impact though.

Also, how long is your coax? Part of that 102" magic is having an 18' coax cable.  Basically just tie the extra up under the dash.  Cutting or using a shorter than 18' coax will hurt signal.

buckallred said FYI - The "CB guru" dude's name is Doug in Fair Oaks. He works by appointment only. If you need CB help you can call him at (916) 988-4589.  

I used this business in the past. He does good work at a fair price. Location is in a decent neighborhood.