[TowerTalk] 2-el 15/20 meter duobander

[Tom Hellem]

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 at telus.net> wrote:
> 
> Date: Tue, 28 Nov 2017 16:38:40 -0700
> From: W0MU Mike Fatchett <w0mu at w0mu.com>
> To: towertalk at 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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