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Re: [TowerTalk] K9YC Choke Cookbook Question

To: towertalk@contesting.com
Subject: Re: [TowerTalk] K9YC Choke Cookbook Question
From: Wes Stewart <wes_n7ws@triconet.org>
Date: Sun, 5 Feb 2017 20:24:32 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
If you follow this link http://k6mhe.com/n7ws/Ladder_Line.pdf to my paper and look at Table 1, it gives the measured values of four different Wireman P/Ns.

Note that these are 50 MHz values and transmission line Zo and Vp are anything but constant at lower frequencies. Likewise, these particular lines use copper-clad steel conductors that "misbehave" at lower frequencies so Eq 4 somewhat falls apart when the conductors do not have a well-developed skin effect. I mentioned this in the paper but did not account for it in the equation.

Wes  N7WS

 On 2/5/2017 5:11 PM, Hardy Landskov wrote:
Hi Jim and all,
The email below reminds me of a problem I had some years ago with "450 ohm
window line". Nothing seemed to work. I then found an article that explained
how to measure the Zo of coax/ladder line. I measured a piece of window line
and it was 374 ohms! I found out in the archives that W8JI had measured 377
ohms with a piece of window line. We exchanged emails and he was elated that
I had verified his results.
Here you have two different sets of equipments, two different runs of ladder
line, and different times. I was very happy myself. I have an HP8753B so it
was no problem to run through the numbers. It was a very eye opening
exercise!!
Bottom line: Use 375 ohms for matching tuners and other things when using
this line.
73 Hardy N7RT/4


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