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Re: [TowerTalk] Coax Question

To: "towertalk@contesting.com" <towertalk@contesting.com>
Subject: Re: [TowerTalk] Coax Question
From: "Jim Brown" <jim@audiosystemsgroup.com>
Reply-to: "Tower and HF antenna construction topics." <towertalk@contesting.com>
Date: Mon, 12 Apr 2010 23:04:08 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
On Mon, 12 Apr 2010 21:07:25 -0400, Steve Bagley wrote:

>I am putting up a tower and will need to run about 500 feet of coax. 

http://audiosystemsgroup.com/Coax-Stubs.pdf

500 ft is a LONG run. You can easily burn half your TX power (3dB) in the 
coax. Many of us try to keep feedline loss under 1 dB. 500 ft of LMR400 is 
3.3 dB on 10M, 2.3 dB on 20M. Half-inch heliax is 1.1 dB on 20M, 1.6 dB on 
10M. To get under 1 dB on 10M you'll need 7/8-inch Heliax. :)  

Another option to consider is CATV hardline. It's pretty low loss, it is 75 
ohm cable, so there will be a bit of mismatch, but that's why God made 
antenna tuners. It's often possible to get it free or cheap. You'll have to 
buy or scrounge connectors and a tool. 

Study the data on W3LPL's and K1TTT's website and save your pennies.   

73,

Jim K9YC





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