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Re: [TowerTalk] 40 meter dipole

To: towertalk@contesting.com
Subject: Re: [TowerTalk] 40 meter dipole
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Mon, 2 Oct 2023 09:57:28 -0700
List-post: <mailto:towertalk@contesting.com>
On 10/1/2023 5:17 PM, Gene Smar via TowerTalk wrote:
You will need to wind a coax balun for the feedpoint - IIRC, it's 12 turns 
about 6 inches in diameter.

That "balun" is really a lousy common mode choke. A far better thing to use there is a really good common mode choke using these guidelines.

http://k9yc.com/2018Cookbook.pdf

The pattern of a dipole is quite broad, with deep nulls off the ends. Those nulls are pretty narrow, and are really what matters. And what matters far more is height -- study this piece, which I wrote for NCJ, but ARRL rejected because the graphs were too much work for their graphics department.

http://k9yc.com/AntennaPlanning.pdf

Dipoles are great antennas. As the link shows, higher is better! For 17 years, I've had dipoles for 80 and 40 at right angles to each other at 125 ft, and for about ten years, at 100 ft for 30M.

73, Jim K9YC

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