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Re: Topband: Feeding vertical

To: topband@contesting.com
Subject: Re: Topband: Feeding vertical
From: "Dan Zimmerman N3OX" <n3ox@n3ox.net>
Date: Mon, 11 Dec 2006 09:26:22 -0500
List-post: <mailto:topband@contesting.com>
A simple L-network should have very modest-value components to match
this thing on 160.  I assume the towers are 1/4 wavelength (280 feet)
at 870KHz.

A very wild guess for the impedance on 1.8MHz based on a 280 foot
radiator 24 inches in "diameter" might be 500-j500.  If so, an L
network to match to 50 ohms would have a 16 microhenry inductor
between antenna feedpoint and ground and a series cap of about 400pF.
Not very hard to come by.

Of course, these values aren't worth much aside from a possible
starting point for experimentation to find a match.  The actual
impedance of the tower on 160m could be all over the place depending
on face width and exact height and so forth.


73,
Dan
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