On the relative efficiency of T-networks vs. L-networks: it's very
instructive
to play with the simulated T-net tuner from Kevin Schmidt, W9CF on:
http://fermi.la.asu.edu/w9cf/tuner/tuner.html
This is a simulated C1-L-C2 T-network that you can tune yourself, and
which tells you
the overall efficiency once you're matched . You can set up your own
component values,
so by making either C1 or C2 extremely large, you can effectively turn this
simulated T-network
into either a Lo-Z or a Hi-Z L-network. All other things being equal,
it's easy to demonstrate on this
simulator that, once you have a match, the L-network efficiency wins over
the
T-network.
This T-net simulator is great fun to play with, as well as being very
instructive!
73
Darrel, aa7fv.
================================================
Date: Tue, 22 Mar 2005 09:03:12 -0500
From: "Ten-Tec Inc. Amateur Radio Sales" <sales@tentec.com>
Subject: Re: [TenTec] apparent match possible in T Tuner
To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Message-ID: <6.2.1.2.1.20050322085730.04d833a0@tentec.com>
Content-Type: text/plain; charset=us-ascii; format=flowed;
x-avg-checked=avg-ok-2062C3E
At 09:15 PM 3/21/05, you wrote:
>Do you mean to say you really might not be able to notice that all the RF
is
>just circulating in the tuner with a T match instead of going out to the
>antenna if you get the "false" match? There would be no indication of this
>except nobody would answer you because your signal would be so weak? Does
>that really happen to people???
Jeff - the answer is "sure". There is no way for you to assure that you've
adjusted the T for the most efficient match. The beauty of the L network
is
that there is only one possible match for a given load.
A reading of the antenna tuner market survey article that appeared in the
February 2003 QST, page 69 would be a good complement to this
discussion. It can also be read on-line by ARRL members at:
http://www.arrl.org/members-only/prodrev/pdf/pr0302.pdf
Scott Robbins
W4PA<
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