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Re: [TowerTalk] Determining coax length?

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Determining coax length?
From: Jim Lux <jimlux@earthlink.net>
Date: Tue, 12 Nov 2013 05:55:47 -0800
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
On 11/12/13 5:49 AM, Rich Hallman - N7TR wrote:
I am stacking several mono banders with a stackmatch II.    I have the antennas 
mounted on the towers, but the coax feedlines are different lengths right now.  
  The Stackmatch wants coax lengths to both antennas to be the same length, but 
I'm unable to physically measure to the end of the feedpoints on the boom.  All 
coax is the same (RF Davis Buryflex)

Questions:

1)      How critical are the coax lengths to the stackmatch from each stacked 
antenna?
2)      What tools can I use to determine the length of coax to each antenna?  
(AIM 4170, MFJ, etc?)  and how do you determine equal lengths?


The antenna likely presents a serious mismatch at frequencies other than in the ham bands, so you can sweep it with the AIM or MFJ, and look for where the Z is low and peaks. The spacing of the peaks tells you the electrical length of the coax.



Thanks...
Rich

Rich N7TR
ex KI3V, N3AMK, WB3JOV
www.n7tr.com<http://www.n7tr.com>
http://www.qrz.com/db/N7TR
Telnet: dxc.n7tr.com N7TR DXCluster


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