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Re: [TowerTalk] 2-el 15/20 meter duobander

To: Jim Thomson <jim.thom@telus.net>
Subject: Re: [TowerTalk] 2-el 15/20 meter duobander
From: Tom Hellem <tom.hellem@gmail.com>
Date: Fri, 1 Dec 2017 16:45:25 -0800
List-post: <mailto:towertalk@contesting.com>
Jim- 
I am curious about why you are suggesting that one needs NEC 4 software to 
design a 2 el. duobander.

FWIW I basically took a C-3 and removed the 10M elements, tweaked it with a 
model in EZnec (NEC 2), built it according to the model. It ended up being 
resonant exactly where the model predicted with an swr of 1.0 at resonance on 
20. However on 15 it ended up with 2.0-1 swr .  Maybe I should have used NEC4.

Tom H
KOSN

> On Nov 29, 2017, at 6:04 AM, Jim Thomson <jim.thom@telus.net> wrote:
> 
> Date: Tue, 28 Nov 2017 16:38:40 -0700
> From: W0MU Mike Fatchett <w0mu@w0mu.com>
> To: towertalk@contesting.com
> Subject: Re: [TowerTalk] 2-el 15/20 meter duobander
> 
> <Why not take the measurements from a C3?? I think it is just 2 ele on 20 
> <and 15 with 4 on 10.
> 
> ##  wont work.   Different yagi, and even if it did sorta work, he would have 
> to use the
> identical tubing schedule.   Whats  required is  auto ez, NEC-4  and yagi 
> mechanical to
> design the eles. 
> 
> Jim   VE7RF
> 
> 
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