UHF base radio to antenna coax

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Quickcall

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I am installing a UHF radio for GMRS use. Its a 40w transmitter and the antenna is a Tram UHF Base antenna. The distance from radio to antenna is approx 100ft. I am not sure what type of coax to use for this. I was thinking of using LMR400. Any suggestions?
 

Packetpeeker

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Coax

For a short run like that you could use Belden 9913 or equivelant mfg of 9913, it is a comm'l grade coax and performs well, we've used it many times in business and public safety installs with no problems.

We did an install in northeast philly a few years ago using a motorola Gm300 40 watt base radio 460 band, business communications, used belden 9913 and a 3.5 db gain omnidirectional antenna, mounting height 70 ft. (Ground elevation) got good coverage down past phill int'l airport, and well into levittown, vehicles were using same radio 40 watt with unity gain antenna. Not sure how far you want to talk, but just to give an idea.

What you want to look for in different varieties of coax is "Loss" usually will be specified in db's per ft. some coax will have less db loss per ft. also usually more expensive to purchase, but the lower the db loss, the more power will get to the antenna. Some will have solid center conductor and some will have stranded center conductor.

As i stated earlier the 9913 works well but if you want to, research various coax cable on the web and you will see the many types and how they differ from one another. Some have braided shield, some have foil shield, some have both and so on, remember to stay with 50 Ohm coax.

What ever you decide, i suggest a few pointers, if you can try to get your antenna up above the level of the terrain, this will surley give you good distance, ultimately we try to get 60 ft. above sea level for our installs this usually gives good transmission distance.

Hope this was of some help to you, and good luck with your install!!
 
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zz0468

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LMR and 9913 cables are all notoriously noisy in duplex operation. It might work nicely at first, but it's close to a sure thing that after a couple of years, you'll be scratching your head wondering where the desense and noise is coming from. Avoid both for repeater operation if at all possible. Caveat Emptor if you decide to use it.
 

mpddigital

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Motorola and others actually recommend against using LMR, CNT, WBC, or other good aluminum bonded foam dielectric coax for repeaters. I try and steer folks away from them based on some of the weird performance issues we have seen. Issues are present not always but sometimes...

Try a GOOD RG-213, RG-214, for your run. Others will also work. Just listing those easy to find.
 

n5ims

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You may want to go with some Andrew LDF4-50A since it's commercial grade and very low loss for the size. It's quite expensive if purchased new, but you can often find it at quite good prices on ebay or other places for much less from folks selling off their "end-of-reel" lengths. Often they sell it for less than LMR-400 is going for.
 
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