Can't get good SWR readings with antenna tip on! - Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > General Jeep Discussions > Communications and Electronics

Join Wrangler Forum Today

Thread Tools

Please support our sponsors and let them know you heard about them on
Old 09-24-2013, 09:56 PM   #1
Supporting Member

WF Supporting Member
KC10Chief's Avatar
Join Date: Sep 2012
Location: Edmond, OK
Posts: 560
Can't get good SWR readings with antenna tip on!

I just set up a CB radio in my Jeep. It's a 2006 Wrangler. I bought the Teraflex mount that mounts to the tub behind the brake light on the passenger side. The radio is a Uniden PRO520XL mounted to the left of my instrument cluster on a Rugged Ridge mount. I am using an 18' coax cable. My antenna is a 3' Firestik II with the tunable tip. I also bought an SWR meter and read up on all of this stuff to make sure I was doing everything right.

The antenna instructions say that I have to check the SWR readings with that rubber tip on the end of the antenna. Firestik site says the same thing. When I do, I just don't get good readings. The best I can get is with the tip screwed all the way in. Even then, I'm getting about a 1.4 on Channel 1, a 1.8 on channel 19 and a 2.8 on channel 40! However, if I take the rubber tip off and retune, I get great numbers. I get a 1.0 on channel 1, 1.1 on channel 19 and a 1.4 on channel 40. I did this out in the middle of a big field with all of my doors closed, RF gain all the way down, and it just doesn't want to work with that red rubber tip installed. Is my antenna still a bit too long? Making it longer only makes all of the readings go way up. My antenna mount is metal on metal, but I didn't grind off any of the powder coating on the mount. I did drill a hole and attach a ground wire from the mount to the tub. I don't think the mount is the problem. Just the rubber tip for some reason. Thoughts?
KC10Chief is offline   Quote
Old 09-24-2013, 10:02 PM   #2
8052949's Avatar
Join Date: Nov 2012
Posts: 96
Did you remove any of the powder coating on the mount? I had to file some powder coating off a antenna hole and mounting hole in order to get a good ground. Make a ton of difference.

8052949 is offline   Quote
Old 09-25-2013, 02:44 AM   #3
VLal's Avatar
Join Date: Oct 2012
Location: Loudonville
Posts: 26
I'm experiencing the same problem with mine. Been searching the web, and can't seem to find anything. I own a 2012, and using a 3 ft firefly with a firestik side mount. Any advise would be appreciated!
VLal is offline   Quote
Old 09-25-2013, 09:51 AM   #4
firecapt's Avatar
Join Date: Oct 2010
Posts: 111
Had trouble with mine to start with. I too have a side mount and had 3 ft firestik(non adjustable tip). I could not get my numbers down. I called Firestik and spoke with a tech there. He immediately asked if this was a Jeep. Because Jeeps are difficult. He said an adjustable tip 3 ft would be better but would likely still be difficult because of the roll bars and such causing interference. He suggested at a minimum to try a 3ft w/adjustable tip and a 3 inch HD spring. He felt the extra 3 inches the spring provides may be enough. His preferred suggestion was a 4ft firefly(adj. tip). I went with the 4ft and a HD spring. It's a little taller than I prefer and I could cut the height by not using the spring, but the SWR is around 1.5 on 1 and 40.

Click image for larger version

Name:	image-246803511.jpg
Views:	113
Size:	114.6 KB
ID:	377481
firecapt is offline   Quote
Old 09-25-2013, 10:28 AM   #5
Supporting Member

WF Supporting Member
KC10Chief's Avatar
Join Date: Sep 2012
Location: Edmond, OK
Posts: 560
Yeah. I am getting good numbers on mine unless I put that rubber tip on the end. I feel the rubber tip looks a little better and protects the metal end from the elements. But I get a high SWR if I put it on there. I guess it changes the way the antenna vibrates and causes a higher SWR?
KC10Chief is offline   Quote
Old 09-25-2013, 04:19 PM   #6
Join Date: Feb 2012
Location: Tempe, Arizona
Posts: 17
I have the same cb with a 3' firestik an s homemade mount on the tire carrier. Try leaving the screw off completely and put the cap back on. I have gone on their website and it says to try different combinations. I would make sure you have a good ground by running your own ground wire to the inside body instead of trusting the tailgate for a ground. The rubber tip changes the capacitance of the antenna, that is why they say to measure the swr with it on. Good luck!
chuck_tempe is offline   Quote
Old 09-26-2013, 11:40 AM   #7
SecretAgentMan's Avatar
Join Date: Mar 2010
Posts: 300
You can also try tuning it on 20 and check to see if 1 and 40 are acceptable.
04 TJ
- - - -
Has anybody seen Amir???
SecretAgentMan is offline   Quote
Old 09-26-2013, 07:13 PM   #8
BlueRidgeYJ's Avatar
Join Date: Mar 2012
Posts: 4,917
Yes, you should tune to ch 20. Lowest on 20 is lowest across the spectrum, and should be the bottom of a bell curve, not a line (unless you are tuning for a specific channel).
Grounding an antenna is not like grounding a typical load like a light, it is much more of a bonding. A simple small wire to common ground may be woefully insufficient. A quick test method is to take large gauge jumper cables and clip them to the ant mount and jeep frame, then test again. If your numbers get lower, your bond is not good 'nuff. Usually 2-3 means just that.
As said, try different combinations of removing the locknut or screw to shorten it further than it will now go.

Jeeps have plenty of groundplane-able metal, you just gotta get bonded to it.

“Coming of age in a fascist police state will not be a barrel of fun for anybody, much less for people like me, who are not inclined to suffer Nazis gladly and feel only contempt for the cowardly flag-suckers who would gladly give up their outdated freedom to live for the mess of pottage they have been conned into believing will be freedom from fear.”
BlueRidgeYJ is offline   Quote

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Download our Mobile App

» Featured Product

All times are GMT -5. The time now is 06:58 PM.

User Alert System provided by Advanced User Tagging v3.1.0 (Pro) - vBulletin Mods & Addons Copyright © 2016 DragonByte Technologies Ltd.

Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC. is not in any way associated with the Chrysler Motors LLC