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Re: [TowerTalk] 40m 4el KLM - replacing linear loading with coils

To: towertalk@contesting.com
Subject: Re: [TowerTalk] 40m 4el KLM - replacing linear loading with coils
From: David Gilbert <xdavid@cis-broadband.com>
Date: Tue, 28 Apr 2020 15:20:15 -0700
List-post: <mailto:towertalk@contesting.com>

Definitely true.

There is some benefit, however, to use two loading coils on either side of center for each element (instead of center coils) because that gives better current distribution along the elements.  Most modern Shorty-40's do this, and it's the same reason why some mobile vertical antennas use center loading instead of base loading.

I suspect that using two coils for each element might even be stronger mechanically since the split elements have less cantilever weight where the two coils are positioned versus a single center one.

73,
Dave   AB7E



On 4/28/2020 2:19 PM, jimlux wrote:

One could also simplify the overall design - make all elements exactly the same length, and use different values of the center loading inductance to "tune" the elements.  There's nothing special about the physical length of the elements, other than it creates the right impedance at the right frequency, and you can get there with loading reactance.

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