[TowerTalk] Link Antenna Tuner

[Barrie Smith]

----- Original Message ----- 
From: "Chuck Pool" <aa5wg at yahoo.com>
To: <TowerTalk at contesting.com>
Sent: Thursday, June 14, 2007 5:19 AM
Subject: [TowerTalk] Link Antenna Tuner


> Hi to all:
>   Does the swinging link method of input for the Link Antenna Tuner work
well vs. the fixed link with a variable capacitor in series for tuning?  Any
thoughts on this?
>   Chuck - AA5WG

Chuck:

The information I have is from "shade-tree-mechanic" experience.  I'm not an
electronics expert!

Using the Cebik tutorial as a guide, I built a large balanced antenna tuner
several years ago for use on 160, 75 and 40 meters.

My tuner uses "dual-differential" capacitors on the output, which I had to
build, since I could find none used, and the price of new was way beyond my
means.

I use  plug-in "kilowatt-coils", with adjustable link-coupling.

Besides the adjustable link-coupling, I also use a large (3000 pf) vacuum
capacitor in series with the link to ground.

The reason for both the link and the capacitor is that there were times
(especially on 75 meters) when I could not get a good match without using
both.

Perhaps a longer or shorter 600 ohm feedline would change this situation.
On 40 and 160 meters I can use tight coupling, and achieve a good match
using the capacitor only.  On 75 meters, in order to get a good match, I
must reduce the coupling somewhat.

I've ended up with four controls on my antenna tuner, but I can achieve a
very good match to the line.  And, even with 1500+ watts, I find no heating
of any component in the tuner.

Build one, you'll love it.

73, Barrie, W7ALW
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