Coax Length Question

You can also "load" a 10 watt, 50 ohm resistor, and it will show a perfect SWR! You won't have much of a signal, but them "SWR'zzzzzzzzzzzzzzzzzzzzzz will be perfect (I always wondered how many "SWR'ZZZZZZZZZZZ" they could cram into ONE feedline!!!!)

 

I know you are correct, but when us truck drivers get in a truck and want to be able to use our CBs, and don't have the time to perfectly match the antenna to the truck, which is sometimes almost impossible on the newer trucks now days anyway, we will use an 18 ft piece of coax to get under 2:1 versus the 9ft coax at over 3:1. So when you guys say "it doesn't make a difference", in real life, with imperfect conditions, it can make a difference in whether you can safely "key-up" your radio or not. Yes I know it doesn't change the SWR, just fools the radio. Sometimes you just have to make do!

 

breaker breaker one nine can i get a radio check

 

Most places sell coax in lengths that are multiples of 3. Ie 3 foot 6 foot 9 foot etc. Find the length that best suites your needs and run with it. Due to routing etc, I ended up using 12 foot. I had to take one of the connectors off to run the coax so that it looked factory. Ie through the mirror arm etc.

I had a pair of wilson 5000s that I had purchased a few years ago. Not that I needed them but hey they were on sale so what the heck. Mounted them both up in the factory locations but only the drivers side is live since that is the side that I routed the new coax too.

 

I was at a well respected CB shop in PA on I-80 (that's enough of a clue) and they insisted 18' was the needed length. I have no argument one way or another, but for those of us who aren't all that interested in the theory and technical aspects of the hobby and just want the radio to work as good as possible, it's confusing to hear all the differing opinions from those who know.


I just think it takes about 18' to go from a mirror bracket, through the door, up the A pillar and into the overhead console.

And what about the mag mount antennas? They come with 15-17' of coax.

 

Next time they say it has to be 18' long, ask them why. If they say that it's a half wavelength, kindly point out to them that a half wavelength of coax is more like 12'...

 

Yes I know, it changes your swr too....kinda like a antenna tuner.

No doubt, but I'm just trying to fool the radio so I can use it safely.

Kinda like a antenna tuner, but it does keep you from ruining the finals.

 

I guess I'll have to find some place to put that extra 9' of cable somewhere.<============you can cut it in half, get 3 new PL259 ends and have a spare 9 foot of coax that is wired ready to go.

 

Maybe this "Coax Length Calculator" can help you decide what length of coax you need to use...

http://highfields-arc.co.uk/constructors/olcalcs/coaxcalc.htm