Coax question...

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Peanut
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Coax question...

#77979

Post by Peanut »

I have a general question about coax lenghts. My antenna is mounted on the right side rear of my tool box. I am going to move it tool the middle. The only problem I have is 18ft. wont reach the way I have it ran which is really the only way I want to run it....it looks professional the way it is ran. I have heard some people say that 18ft is the ideal length to use whether you need that much or not. My question for yall is, do you have to have A CERTAIN AMOUNT, or just use however much you need to do the job. I figure I will need around 22ft to get it the mount where I want it. My swrs are 1.1 on my 10k, will the swrs change or performance go down with 3 or 4 more ft. of coax? Thanks in advanced!!
John 3:16
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Rex_foxhound

#78012

Post by Rex_foxhound »

Use whatever length you need to get the job done.
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#78029

Post by Peanut »

Thats what I was thinkin. Thanks Red!!!
John 3:16
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DJboutit

#78423

Post by DJboutit »

Measure how far the distance use about 1ft 1 1/2ft more than you need using to much will mean lots of power loss @ the antenna
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Big B
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#78470

Post by Big B »

DJboutit wrote:Measure how far the distance use about 1ft 1 1/2ft more than you need using to much will mean lots of power loss @ the antenna
First off, if you use good quality coax, using a little more length than you need will NOT cause lots of power loss. Coax length is probably the most misunderstood and incorretly recommended advice in radio communication. 18 feet IS NOT the perfect length unless you are using a coax with a velocity factor of 66% (.66) and you need around ¾ wavelength of feedline. There is a specific formula for figuring coax length, just like EVERYTHING ELSE in the world that's governed by math, physics, mother nature, and common sense. If anyone tells you different, RUN don't walk away from them. The ARRL handbook has a whole chapter that deals with feedline, READ IT. 8)
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MOONSHINER
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#78547

Post by MOONSHINER »

run what ya need to get to the antenna. a little more wont hurt. at the cb frequency, coax loss isnt that big of a deal. The higher the freqs get (vhf/uhf), db loss becomes more important.
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