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Re: [CQ-Contest] Coax stubs located at outside antenna switch?

To: cq-contest@contesting.com
Subject: Re: [CQ-Contest] Coax stubs located at outside antenna switch?
From: Jim Brown <k9yc@audiosystemsgroup.com>
Reply-to: k9yc@arrl.net
Date: Fri, 12 Jul 2024 23:39:55 -0700
List-post: <mailto:cq-contest@contesting.com>
On 7/12/2024 3:31 PM, Mike Smith VE9AA wrote:
I am thinking of modifying my SO2R station's antenna setup (would take too
long to explain what craziness I have going on here now, hi) but do any of
you locate coax stubs outside, at your remote antenna switches?

Hi Mike,

The effectiveness of stubs is quite sensitive to their precise position along the line. I've done serious work on this, and published it several years ago in National Contest Journal. It's on my website.

http://k9yc.com/LocatingStubs.pdf

There's also a slide pdf for talks I've done about it at Visalia and Pacificon and to some clubs.

http://k9yc.com/StubPlacement.pdf

The answer is yes, they can go on the antenna side of the switch, but you've got to go through the calcs to figure out where to put them along the line to each antenna if you want them to be effective. My work is specifically directed to stubs to kill the second harmonic of power amps.

73, Jim K9YC



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