Cb coax length

[jeeeep]

well if I were driving a big rig with dual antennas that may apply but in all the Jeeps I've owned I've always used the distance needed to get from the radio to the antenna. I have great range and low SWR, a proper installation will give you great results.

 

[pastorwug]

What? I can't hear you, must be your SWR! ; >)


Sent from my iPad using WAYALIFE mobile app

 

[KJ_CJtoJK]

Wonder why kj-cj needed 24 feet

jeepin on a budget

My routing (24 ft) ran across the top of the windshield and down the passenger side windshield pillar and down to the passenger floorboard and then under the trim at floor then up to the top of the tub (behind passenger seat) where the tail light wiring is run. It follows the 3rd brake light wiring into the tailgate and then out the spare grommet to the antenna mount on the spare tire carrier.

 

[pastorwug]

My routing (24 ft) ran across the top of the windshield and down the passenger side windshield pillar and down to the passenger floorboard and then under the trim at floor then up to the top of the tub (behind passenger seat) where the tail light wiring is run. It follows the 3rd brake light wiring into the tailgate and then out the spare grommet to the antenna mount on the spare tire carrier.

A good plan :thumb:

 

[miguel250r]

So I have another question about this topic but this time it's about my single cab truck I have a 9 ft coax with a 4' fire stick with the screw on top to adjust it but no matter where I put the adjustment screw it always pegges out my swr meter do u think I need to switch to a 18ft coax to get my swrs way down

Sent from my DROID RAZR using WAYALIFE mobile app

 

[IBeHeWhoIsJoshua]

My routing (24 ft) ran across the top of the windshield and down the passenger side windshield pillar and down to the passenger floorboard and then under the trim at floor then up to the top of the tub (behind passenger seat) where the tail light wiring is run. It follows the 3rd brake light wiring into the tailgate and then out the spare grommet to the antenna mount on the spare tire carrier.

I ran my 18ft across windshield and through the roll bar padding. Followed the third brake light wiring and out the passenger side grommet to rugged ridge mount.

 

[miguel250r]

I ran my 18ft across windshield and through the roll bar padding. Followed the third brake light wiring and out the passenger side grommet to rugged ridge mount.

Seems like everyone is using 18 feet maybe that's why I can't get my swrs low enough Cuz I have 9' in my truck my jeep is 18' n swrs are fine

Sent from my DROID RAZR using WAYALIFE mobile app

 

[jeek.olllllllo]

I'm using a 18 foot from the rear to the top of my rear view mirror running it in the roll cage I have about a foot left over. I have a jku
When I ran it from the bottom I was only able to get under the glove box

 

[jeek.olllllllo]

Is it grounded well?

 

[pastorwug]

Take a look here:

http://www.firestik.com/Tech_Docs/Setting_SWR.htm

 

[miguel250r]

Ya its grounded good but the swr meter im using is built in on the cb its a cobra 29.. my Cb also has been peaked tuned and aligned could it just be to much power for a fire stick?

Sent from my DROID RAZR using WAYALIFE mobile app

 

[OverlanderJK]

So I have another question about this topic but this time it's about my single cab truck I have a 9 ft coax with a 4' fire stick with the screw on top to adjust it but no matter where I put the adjustment screw it always pegges out my swr meter do u think I need to switch to a 18ft coax to get my swrs way down

Sent from my DROID RAZR using WAYALIFE mobile app

Are you on SWR or CAL?

 

[miguel250r]

Are you on SWR or CAL?

I did just what the instructions said I put it on channel 20 with it on cal adjusted it to were the needle is in the cal mark then flipped the switch to swr and the needle goes past the cal mark

Sent from my DROID RAZR using WAYALIFE mobile app

 

[miguel250r]

I'm pretty luiry about the coax I got it from a place that we get all of our coaxes at from work here locally in town and he sold us some junk coaxes before so I wouldn't be surprised if that was the problem

Sent from my DROID RAZR using WAYALIFE mobile app

 

[Bonehead]

I have seemed to notice how the Firestick antenna is a big thing among jeepers......really not sure why but that is besides the point LOL
After many many years of driving 18 wheels using CBs ranging from the Cobra 23 ,29 ,148 GTL to stuff like higher end Connex and Galaxy radios with both Steel (Wilson) and fiberglass antennas I will still pick a fiberglass Francis antenna over all others!!!!!
That being said a good proper length Co-ax is very important and not bundling it up to take up room......if you have to run it all the way around the jeep a couple of time so be it LOL
You must also have a good ground between the antenna and the mount , the mount and the Jeep even if you need to run an extra ground wire for it............. oh and one more note take the spring mount and chuck them as far as possible they because nothing but issues.

http://www.francisantennaonline.com/francis_antennas.html

Ok I will shut up now

 

[miguel250r]

Does the cb itself need to be grounded Cuz I just have it mounted to a plastic dash

Sent from my DROID RAZR using WAYALIFE mobile app

 

[JEEPnGEO]

In a 2-door, you should have more than you know what to do with if you get a standard 18' cable. Just make sure not to loop the extra length in a coil as that will effect your reception/transmission negatively.

Second on that answer. 18 feet is minimum. Mine is attached to the front bumper and my slack sits in the wheel well and a little behind the glove box. My CB is attached above my rear view mirror.

 

[OverlanderJK]

Does the cb itself need to be grounded Cuz I just have it mounted to a plastic dash

Sent from my DROID RAZR using WAYALIFE mobile app

No it doesn't.

 

[miguel250r]

No it doesn't.

OK I'm pretty sure its the coax I tried 3 different antennas and 2 different antenna mounts and same thing

Sent from my DROID RAZR using WAYALIFE mobile app

 

[prerunner1982]

Ok.. I know this is an old thread but there is a bit of mis-information that I feel needs to be corrected.

18' of coax is NOT required. If you have a properly mounted resonant antenna with a 50 ohm impedance (most single vertical mobile antennas) and a 50 ohm feedline (RG58 or RG8 typically) any length of coax will work and you will get the same SWR reading anywhere along that length because your antenna and coax are matched.

If your SWRs are off the charts, fix your antenna don't adjust your coax. By adjusting your coax you are hiding the issue from your radio (and yourself). If the SWR is off the charts you likely have a ground plane issue. Your antenna is probably mounted to your tailgate or spare tire rack or your antenna mount is powder coated/painted and not making sufficient metal to metal contact with the body of the vehicle. When this happens your antenna is using the coax as it's ground plane (wrong) and you see high SWR. By making the coax 18' it is in the null of the wave so you see a low SWR. It's a bandaid like replacing a steering stabilizer to fix death wobble. You could also have extremely high SWR if you have a bad piece of coax.

If your antenna and coax are matched (1:1 SWR or damn close) your will have no/little reflected signal and therefore nothing to hide from your radio.

Saying you need a certain length of coax for a certain frequency is almost like saying you need a certain length hose for a certain PSI or a certain length wire for a certain amperage.

Also.. coiling the coax, it's called an RF Choke, Choke Balun, or Ugly Balun though not really a balun at all but indeed a choke they are common and won't hurt your signal and on't fix your SWR but it will "choke" off stray RF.