[TowerTalk] Determining coax length?
jimlux at earthlink.net
Tue Nov 12 08:55:47 EST 2013
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)
> 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.
> Rich N7TR
> ex KI3V, N3AMK, WB3JOV
> Telnet: dxc.n7tr.com N7TR DXCluster
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