I tried to run my coax tonight for my unlimited. I have a cobra 29 and im mounting it right above my rear view mirror with a homemade mount. I ran the coax 18' from the teraflex mount and followed the floor then up along the front door pillar. I am about 4 inches short. Im assuming others have run their cable the same way. Does anyone know if there would be any issue if i run the coax up along the roll bar instead and then what would i do with the extra coax length?

 

Cut, crimp and cap it with a crimping tool

 

would i need to take off 3' to stay within the rule of 3's for optimal use.

 

I ran my HF coax along the roll bar with no problem. Make sure it doesn't get pinched, and make sure it's out of the way of the removable top pins and clamps. You'll notice that Jeep also runs conductors along the roll bar, so just add to it.

If there's extra coax, just coil it and tuck it out of the way.

Hope this helps.

 

Not sure what the rule of 3 is but, cut and crimp or buy a jumper and a barrel and add what you need. All will be well.

There are other things to consider when choosing the "perfect" length of cable like the Velocity factor of said cable. This wasn't taken into account when folks came up with 18ft being the perfect length of coax. While 18ft is a half wavelength at the center of the CB freq range this assumes a perfect cable able to transmit a signal at light speed. Which cables can't do. RG-8 has a velocity factor of .66 so the perfect length is roughly 11.9ft.

Math for 1/2 wavelength cable:
492/27.205 = 18.08 No velocity factor considered
(492*.66)/27.205 = 11.94


What's of more interest is cable losses and SWR impact. Google: Ham Coax loss Calculator. It will give you and idea of efficiency of your rig at a given cable length with a given SWR for your desired frequency. Your center frequency is 27.205 or ch20.

 

That 3 foot "rule" is an urban legend.

Extra cable should be randomly tucked in but not coiled.

If you are a little short don't worry...just get a SO239 barrel connector and a short jumper.

No worries it ain't rocket science

 

Sorry guy...I've told you about this before but you still keep saying it. A coiled section of coax can be beneficial, but it should be as close to the antenna feed point as possible. It's called a "coaxial choke". Google "RF coax choke" and read up. Thousands of HAMs, including myself, build, and use them purposely

 

bad idea X2, been using CB,s for 30 years and it is not a good way to set up. When you think about it a bottom or top coiled antenna still has the ability to be tuned. It will make a difference in match so just plan your route through the vehicle to use all the cable without coil. Run good cable!

Dave where you at, I run lower SB on 38......................skipland, skipland.

Ontario Canada Mobile 512.

 

Have 18 feet in my unlimited with cb mounted center top dash, lots of cable to route along wheel well under rear seat, under front seat to the kick plate passenger side, up side door sill (A post) to gap between windsheild and to radio.

I have a friend who runs ham in his ram, lol...................takes him forever to crank down his power antenna, adjust the matcher and turn down his power to talk on CB channels.

Setup a simple 40 channel radio, basic antenna and you will talk for miles on 4 watts.