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Topic Review (Newest First)
03-26-2013 01:40 PM
Jerry Bransford Based on that high of an SWR, if you have installed a standard antenna mount like shown below which has an S0239 connector on the bottom, odds are very good the mount has been simply misassembled or installed. Or the nylon insulating shoulder washer is missing or improperly installed which is very common.

Can you take a good sharp clear close-up photo of the top & bottom of your mount so we can possibly spot what the problem is?
03-26-2013 01:34 PM
Redrider94 Sounds like the mount is not grounded, try running a wire from the ant mount to the frame or a good ground. If swr comes down then look and see how to ground more permanent. Post a pic of how you have it mounted now and I may be able to offer more help.
03-26-2013 01:04 PM
travis1953
CB tuning,

Hello everyone in Wrangler land, I just signed up and I just got my first Jeep a few months ago (2003 Wrangler Sport), I just installed a CB It's a new Galaxy along with 18' of new coax, a new antenna mount (mounted on the old doorless mirror mount, drivers side) and a new 5' tunable Firestik, the top is a soft top, I can't get the match any lower than a 3.1 to 1. Does anyone have any ideas of what I may have missed, I drove semi for 35 years and always had CB's but after 5 years of retirement I guess I've lost my touch....... Thanks.
04-23-2012 05:02 PM
lindel Good article, thanks.

Aside from CB, my radio experience comes from working with FAA radios. My other electronics experience comes from many years of assorted radars and 20 years of Instrument Landing Systems and VOR systems. Phasing and electrical coax length is a big part of my life.

I install stereos/CBs on my own and family vehicles, but nothing more, and I haven't worked on a TV in a decade or more.
04-23-2012 04:39 PM
Chunks
Quote:
Originally Posted by lindel View Post
Apparently, Firestik (or more importantly, the company that owns/builds Firestik), still hasn't discovered the "Rules of Radio Science". Jerry gave you a couple of links that will give all the references you need to put the 18' myth to rest.

There are applications that require specific lengths of coax, but communications radio isn't one of them. Your main concern with radio is impeadance matching, which you do with the antenna adjustment.
Here's some more good reading if you're interested in getting the most out of your mobile installation. Alan's website covers mobile installations (CB/Ham), proper installation and myths that have been around for a long time.

Antenna Myths

An example:
Coaxial myth one: Several antenna manufacturers suggest using a specific length coax cable between the transceiver, and the antenna. Or, they suggest using an open stub cut to some length. Both of these schemes are SWR patches, not fixes. Shunt matching is the only correct way to match a remotely tuned HF mobile antenna to 50 ohms. If you read the article, you'll know why.

Coaxial myth two: Using the best grade of coax money can buy, will be worth the expense. Not! There are two aspects of this myth. First, the the length of coax used in the average mobile installation, seldom exceeds 10 feet. Thus the difference between say RG213, and RG8X, is less than .25 dB! Ah, but there is a hidden facet as well! As mentioned above, it is very important to properly choke off common mode currents from coaxial feed lines, especially mobile ones.

Also, his SWR vs Resonance Myth is great reading and I agree with him 100%.

If you really want the best perfoming antenna for your mobile CB set-up, you can't go wrong with a simple 102" whip.

Regards,
Jim
04-23-2012 02:00 PM
2002TJ
Quote:
Originally Posted by lindel View Post
The reason they claim that you need 18' of coax is two-fold. 1: They want to fit as many cars/trucks as possible, and 2: The more coax they sell (and it's not the high quality stuff) the more money they make.
Yeah, but the cables they sell come without a connector on one end, but they supply the connector for you to solder on. Being in unterminated cable already, we are free to shorten it to our requirements before soldering on the connector, BUT their instructions caution you to NOT shorten their cable, nor coil it to prevent generating a choke effect.

So ok, I'll buy the fact they maybe don't supply the 'best' quality cables and their instructions take that into consideration when it comes to length and coiling.
04-23-2012 12:59 PM
lindel
Quote:
Originally Posted by 2002TJ View Post
Sorry, but I got a problem with that statement....The part about antenna manufacturers insisting on 18' of quality coax not being necessary....Come on, be real....If any leading antenna maker out there (like Firestik), knew their antenna could be installed and work properly with any length coax like you claim, they would fersure promote that fact..It would be a selling/marketing advantage....And they would fersure say, 'hey folks make sure to coil our coax 4-5 turns to provide necessary choke for best results'.

I'm not about to believe the rules of radio science changed since FireStik discovered those facts and insisted we use them with their antennas...Rules of Science don't change, but instead drive industry to find ways around them with advanced tech....Unless you can show me something other than your opinion, I gotta stick with what FireStik says
Apparently, Firestik (or more importantly, the company that owns/builds Firestik), still hasn't discovered the "Rules of Radio Science". Jerry gave you a couple of links that will give all the references you need to put the 18' myth to rest.

There are applications that require specific lengths of coax, but communications radio isn't one of them. Your main concern with radio is impeadance matching, which you do with the antenna adjustment.
04-23-2012 09:05 AM
Jerry Bransford
Quote:
Originally Posted by 2002TJ View Post
Sorry, but I got a problem with that statement....The part about antenna manufacturers insisting on 18' of quality coax not being necessary....Come on, be real....If any leading antenna maker out there (like Firestik), knew their antenna could be installed and work properly with any length coax like you claim, they would fersure promote that fact..It would be a selling/marketing advantage....And they would fersure say, 'hey folks make sure to coil our coax 4-5 turns to provide necessary choke for best results'.

I'm not about to believe the rules of radio science changed since FireStik discovered those facts and insisted we use them with their antennas...Rules of Science don't change, but instead drive industry to find ways around them with advanced tech....Unless you can show me something other than your opinion, I gotta stick with what FireStik says
The 18' thing really is a myth. While some types of balanced antennas do require a specific feedline length, that isn't the case with the types of antennas we use with our TJs.

Here are a couple writeups on the subject.

The Ultimate Guide to 11 Meter CB Antennas (bottom half below Figure 3)
Exposing the 18' CB Coax Myth
04-23-2012 08:33 AM
Chunks
Quote:
Originally Posted by 2002TJ View Post
Sorry, but I got a problem with that statement....The part about antenna manufacturers insisting on 18' of quality coax not being necessary....Come on, be real....If any leading antenna maker out there (like Firestik), knew their antenna could be installed and work properly with any length coax like you claim, they would fersure promote that fact..It would be a selling/marketing advantage....And they would fersure say, 'hey folks make sure to coil our coax 4-5 turns to provide necessary choke for best results'.

I'm not about to believe the rules of radio science changed since FireStik discovered those facts and insisted we use them with their antennas...Rules of Science don't change, but instead drive industry to find ways around them with advanced tech....Unless you can show me something other than your opinion, I gotta stick with what FireStik says
What I stated is not opinion but a known fact.

I guess I'll take my EE degree and my Ham license of 33yrs and throw them in the trash...

Jim
04-23-2012 06:35 AM
lindel The reason they claim that you need 18' of coax is two-fold. 1: They want to fit as many cars/trucks as possible, and 2: The more coax they sell (and it's not the high quality stuff) the more money they make.

If cable length is so critical for CBs, why isn't it critical for radios that Air Traffic Controllers use? Trust me, it's not. It's not critical for any radio that I'm aware of, and I've worked on a few. Shorter is better (less signal loss), and if your antenna "requires" a set amount of cable, I'd look at a different antenna.
04-23-2012 02:24 AM
2002TJ
Quote:
Originally Posted by Chunks View Post
Anyone or any Mfr. who tells you you need to add a certain length of coax to get the antenna to tune doesn't understand how antennas work and is masking the problem rather than providing a solution. Coiling the coax is providing a certain amount of "choking" effect on any common mode currents and that is a good thing. The best choking solution would be to add 5 turns (4.25" diameter coil) of RG-58 coax located as close to the antenna feedpoint as possible. After this is done, then tune the antenna for lowest SWR.

Regards,
Jim
Sorry, but I got a problem with that statement....The part about antenna manufacturers insisting on 18' of quality coax not being necessary....Come on, be real....If any leading antenna maker out there (like Firestik), knew their antenna could be installed and work properly with any length coax like you claim, they would fersure promote that fact..It would be a selling/marketing advantage....And they would fersure say, 'hey folks make sure to coil our coax 4-5 turns to provide necessary choke for best results'.

I'm not about to believe the rules of radio science changed since FireStik discovered those facts and insisted we use them with their antennas...Rules of Science don't change, but instead drive industry to find ways around them with advanced tech....Unless you can show me something other than your opinion, I gotta stick with what FireStik says
04-22-2012 05:24 PM
hambubba
Quote:
Originally Posted by Jerry Bransford View Post
Good quality
You said that 4 times. That's the point. I've used coax I've stripped off other projects, quality unknown, for radio stuff, back when I was a little less poor. Even that stuff, when you do it right and LEAVE IT ALONE works *most* of the time. There's some really cheap and poorly made stuff out there, you gotta watch what you get. Name brand doesn't necessarily mean it's good. Check local ham stores and hamfests and buy a spool of "good stuff" for the group to use.
04-22-2012 02:07 PM
Jerry Bransford Good quality RG8x coax is no better quality than good quality RG58. RG8x has very slightly less loss per 100' but for a run of 12-18', it is totally and completely inconsequential. The benefit of good quality RG58 over good quality RG8x is that RG58 has a smaller diameter and is easier to run and route which is good for a Jeep where it's not all that easy to run cable. For a 4 watt CB installed in a Jeep, good quality RG58 is a very good choice that will perform well.
04-22-2012 01:18 PM
2002TJ That's good info on coax, but hardly worth the trouble now that it's installed and working well...I just went with FireStik brand coax and it was braided shield with stranded core, but no added foil, so I can see where it might leak when coiled tightly against itself like I had it.

I'm chasin a small water loss problem. If it turns out to be the heater core the whole dash will come out and then I'll see about shortening the coax on reassembly.
04-22-2012 12:31 PM
hambubba If your SWR changes when you coil your cable, I suspect you haven't got very good cable. Shielding is very important; some cables have braid only, some have braid AND foil. Here's a wiki with some cable types. Amateur radio cabling is usually better stuff, same impedance. You might have to find a different connector for the outside diameter. Stay away from cheap RG58, find some with better shielding or use something like RG8X, which is much better.
04-22-2012 09:27 AM
Jerry Bransford
Quote:
Originally Posted by Chunks View Post
Anyone or any Mfr. who tells you you need to add a certain length of coax to get the antenna to tune doesn't understand how antennas work and is masking the problem rather than providing a solution.
True. And as often as I recommend Firestick antennas for Jeeps and like their products, their website persists in promoting that old wive's tale that the coax cable length should be 18' for a CB. A little electronics training makes that sound reasonable. More electroncs education soon disproves it.
04-22-2012 08:21 AM
Chunks
Quote:
Originally Posted by 2002TJ View Post
All Stop! Hang on! Back up!.

LOL, so easy to disprove/prove this statement about coiling coax....Try it both ways like I did.

When I coiled the extra 7' of coax and stuffed it under my dash, SWR's were at +3 across the scale...I cut the tie wrap and uncoiled it and stretched out the coax into one big open loop and let it hang out the door and SWR dropped to 1.7 or so then I could tune the tip of my antenna and get them down to 1.25...from there I carefully ran the extra coax up under the dash from drivers side to passenger side then up to CB on roll bar and SWR's remained 1.25.

Try it coiled and uncoiled and let your meter show what's best.
OK, let's tackle the coax length, coiled uncoiled etc.. The bottom line. If your swr changes when adding coax or removing a certain amount of coax then you have a problem with your installation. If coiling or uncoiling coax changes the swr, then it's your coax that is radiating and not the antenna.

This is a common problem with using "electrically short" loaded antennas. What results is a situation called "common mode current" where the feedline is actually doing more of the radiating rather than antenna.

Anyone or any Mfr. who tells you you need to add a certain length of coax to get the antenna to tune doesn't understand how antennas work and is masking the problem rather than providing a solution. Coiling the coax is providing a certain amount of "choking" effect on any common mode currents and that is a good thing. The best choking solution would be to add 5 turns (4.25" diameter coil) of RG-58 coax located as close to the antenna feedpoint as possible. After this is done, then tune the antenna for lowest SWR.

Regards,
Jim
04-21-2012 10:09 AM
2002TJ
Quote:
Originally Posted by 2004_Silver_Sport View Post
Does the SWR meter need to be level? I noticed that if I barely moved the SWR meter the reading would change.
No, it can be in any position....Just tie/tape or anchor it off so it stays in that position while testing...you already saw the needle will swing if meter is shifted, so keep it in same position while testing so you don't skew the results.

These litte inexpensive meters we tend to buy are not lab quality calibrated devices, but they work well enuff to indicate a reaction to our ajdustments.

That said, if you want, you can play with meter position until it reads lowest, then tie it off in that position.....but that really isn't necessary as long as it's anchored against reorientation while testing.
04-21-2012 10:00 AM
2002TJ
Quote:
Originally Posted by GoldenSahara00 View Post
First of all you have the exact same setup as me. I might have the 4 foot fire stick though. Same antenna. Anyways coiling it doesn't matter. Jerry said it himself in another thread. As far as swr. I got my meter and everything. Turned out it was broken. I said screw it, fired it up, tuned it with a buddy. Works awesome.
All Stop! Hang on! Back up!.

LOL, so easy to disprove/prove this statement about coiling coax....Try it both ways like I did.

When I coiled the extra 7' of coax and stuffed it under my dash, SWR's were at +3 across the scale...I cut the tie wrap and uncoiled it and stretched out the coax into one big open loop and let it hang out the door and SWR dropped to 1.7 or so then I could tune the tip of my antenna and get them down to 1.25...from there I carefully ran the extra coax up under the dash from drivers side to passenger side then up to CB on roll bar and SWR's remained 1.25.

Try it coiled and uncoiled and let your meter show what's best.
04-20-2012 11:28 PM
2004_Silver_Sport Got my SWR down to 1.2. I replaced the antenna mount with a new one since I noticed that the mount I was using was pretty corroded up with rust. The washer and stud were caked with rust and were horrible. And followed Firestik's write up on how to tune it. All is great now. Looking forward to using it out on the trail.
04-20-2012 09:27 PM
GoldenSahara00
Quote:
Originally Posted by 2004_Silver_Sport

I've read that I shouldn't coil my excess coax and then I've read that it doesn't matter. I know your have a lot of communication experience so I'll ask you. Does it matter if I coil my excess and will it effect my SWR? Right now my SWR is at about 2.5ish. I'm working on getting down to that 1.5 or below. Don't know if it matters what my setup is but it's a Uniden 520 Pro CB with a 3' Firestik FS antenna with adjustable tip and 18' coax cable. Thanks in advance Jerry and everybody.
First of all you have the exact same setup as me. I might have the 4 foot fire stick though. Same antenna. Anyways coiling it doesn't matter. Jerry said it himself in another thread. As far as swr. I got my meter and everything. Turned out it was broken. I said screw it, fired it up, tuned it with a buddy. Works awesome.
04-20-2012 09:12 PM
2004_Silver_Sport
Quote:
Originally Posted by Jerry Bransford
It is mechanical so I can see the needle moving a tad if you tip/tilt the meter. I don't worry too much about the exact SWR the meter is indicating so long as the antenna has been tuned to give the lowest possible SWR and that the SWR is somewhere under 1.5:1.
I've read that I shouldn't coil my excess coax and then I've read that it doesn't matter. I know your have a lot of communication experience so I'll ask you. Does it matter if I coil my excess and will it effect my SWR? Right now my SWR is at about 2.5ish. I'm working on getting down to that 1.5 or below. Don't know if it matters what my setup is but it's a Uniden 520 Pro CB with a 3' Firestik FS antenna with adjustable tip and 18' coax cable. Thanks in advance Jerry and everybody.
04-20-2012 06:47 PM
Jerry Bransford
Quote:
Originally Posted by 2004_Silver_Sport View Post
Does the SWR meter need to be level? I noticed that if I barely moved the SWR meter the reading would change.
It is mechanical so I can see the needle moving a tad if you tip/tilt the meter. I don't worry too much about the exact SWR the meter is indicating so long as the antenna has been tuned to give the lowest possible SWR and that the SWR is somewhere under 1.5:1.
04-20-2012 03:41 PM
2004_Silver_Sport Does the SWR meter need to be level? I noticed that if I barely moved the SWR meter the reading would change.
04-05-2012 06:50 PM
Chunks
Quote:
Originally Posted by 2002TJ View Post
Well, maybe, and maybe not.....Odds are you came here because you are having trouble reaching an acceptably low SWR (below 2.1), so I'll NOT tell you to shorten your coax, or anything other than this:

First try ALL the published-tried n true rules, including starting with 18' of QUALITY coax of the right type.

There's lots of 'little' details concerning CB install and maintenance that if ignored will add up to high SWR, so first play by ALL the rules then once you get really good SWR, try to break the ones you would like to, and see if it has any negitive effect by measuring SWR with each change....And remember this; what works on my Jeep may not work on yours cause each radio/coax/antenna combination is as unique SWR-Wise as we peoples are in other ways.

One little detail many folks don't know is to NEVER loop your extra coax like you would any other wire....When I installed my fender mount antenna, I took the extra 7' of coax and first looped it in a coil and stuffed it up under the dash...My SWR meter showed over 3 across all channels.....

So I uncoiled it and carefully ran it up high behind the dash all the way across to the passenger side and then back to my radio....Then tie wrapped it well out of sight and the way of pedals and steering shaft. I'm now getting 1 to 1.25 with a 3" Firestik mounted on driver side front fender.

I also used factory assembled/moulded Firestik Fire Ring coax and to install the radio end connector very carefully.

When I mounted the Firestik antenna mount to the fender, I made sure to dremmel off paint to bare metal under the mount, PLUS ran a braided ground strap from mount to inner fender bolt.....I then seal the mount to the fender to prevent corrosion.
I'd be more concerned about antenna resonance rather trying to achieve the lowest SWR but that's just me. Also, if the antenna is properly matched, it shouldn't matter how long the feedline is. If adding extra cable does change the resonance of the antenna, there's other issues with the installation and the extra cable is just masking the problem.

Regards,
Jim N9WW
04-05-2012 04:10 PM
Jerry Bransford
Quote:
Originally Posted by G.I. Joe View Post
and came with a 9 ft whip antenna. Will this antenna be fine with the cb and i was planning on mounting on the rear bumper. any help would be great.
That antenna will of course work but it's not a good choice for offroading since it sways so much. Most organized 4x4 clubs and 4x4 offroad events have banned antennas longer than about 50" or so due to longer antennas being a hazard on the trail. Attaching the tip to the forward part of the Jeep won't get you past most 4x4 event safety inspections because they have a habit of breaking free.
04-05-2012 03:18 PM
Chunks
Quote:
Originally Posted by G.I. Joe View Post
So quick question. I am also a very big newbie with cb's.

I have a cobra 19 III i dont remember the exact code but thats it in jist. I got it used off CL for 40 bucks and came with a 9 ft whip antenna. Will this antenna be fine with the cb and i was planning on mounting on the rear bumper. any help would be great. Also came with a PA horn and do not know how to wire the cb, or the pa and would need very basic instructions please. I know the pa needs a mono plug but I dont know what size.

Thanks
Should work out just fine. That antenna's length is a 1/4 wavelength on channel 19. Should match well with a good ground connection and will perform better than any shortened loaded whip antennas.

Enjoy!

Regards,
Jim
04-03-2012 09:48 AM
G.I. Joe So quick question. I am also a very big newbie with cb's.

I have a cobra 19 III i dont remember the exact code but thats it in jist. I got it used off CL for 40 bucks and came with a 9 ft whip antenna. Will this antenna be fine with the cb and i was planning on mounting on the rear bumper. any help would be great. Also came with a PA horn and do not know how to wire the cb, or the pa and would need very basic instructions please. I know the pa needs a mono plug but I dont know what size.

Thanks
03-27-2012 11:53 AM
AC0QR
Quote:
Originally Posted by Jerry Bransford
From 40+ years working with commercial, military, and amateur 2-way radios, I'd never consider 3:1 acceptable
Agreed. Buddy of mine got 3.5:1 on his 2m/70cm spare carrier mount dual band and called it good. I guess "good" can mean anything from "perfect" to "I can almost hit the repeater 5 mi away"
03-27-2012 10:35 AM
KidRock171 I'm also wanting a firestick. Is there any preference to the KW FS or FL models?
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