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Re: [TowerTalk] hardline sweep - strange result

To: towertalk <towertalk@contesting.com>
Subject: Re: [TowerTalk] hardline sweep - strange result
From: Dan Maguire <danac6la@gmail.com>
Date: Fri, 19 Sep 2025 22:17:59 -0700
List-post: <mailto:towertalk@contesting.com>
Jim Brown wrote:
>>> Can you make sweeps with far end open and short, then export to AC6LA's
ZPlots Excel spreadsheet and have it compute the TL parameters? This might
provide some clues.
>>> Note that ZPlots only runs in Excel, not alternative spreadsheets.

Similar calculations using Zoc/Zsc measurement files can also be done using
SimNEC.  SimNEC is free and can run under Windows, Mac, and Linux systems.

Here's an example using Zoc/Zsc measurements made by KN5L for 24.9 feet of
RG-174.  Red is the calculated Matched-Line Attenuation in dB/100ft, left
(log) scale.  Blue is calculated |Zo|, right (linear) scale.  Green is
calculated VP% (VF * 100), right scale.  Sweep is from 10 kHz to 100 MHz,
log scale.

https://ibb.co/d0YhNhJ6

SimNEC can be downloaded here:  https://www.ae6ty.com/smith_charts/

Please email me directly for a copy of the SimNEC model and the two sample
Zoc/Zsc measurement files.

Dan, AC6LA
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