[TowerTalk] Determining coax length?

[Roger (K8RI) on TT]

On 11/12/2013 8:49 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)
It depends on the accuracy needed, but a simple instrument like the 
4170C  VNA used In Time Domain Reflectometry mode (TDR)will give you the 
electrical lengths in physical dimensions for each cable. You'll be able 
to figure how close they are with in a fraction of a foot IIRC.
> Questions:
>
> 1)      How critical are the coax lengths to the stackmatch from each stacked antenna?

Ask the manufacturer.
> 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 4170 will give it to you in feet and is very easy to use.
You can download the software and use it in demo mode with out the 4170 
to see what it can do.

73

Roger (K8RI)
>
> 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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