Date: Sat, 10 May 2008 18:11:47 -0700
From: "Jim Brown K9YC" <k9yc@audiosystemsgroup.com>
Subject: [TenTec] Measuring High Impedances
To: "Ten Tec List" <tentec@contesting.com>,
"geraldj@storm.weather.net" <geraldj@storm.weather.net>
Message-ID: <20080511010947.00DA7589DA@gw1.nlenet.net>
Content-Type: text/plain; charset="us-ascii"
Jerry,
If you haven't already done so, have a look at the measurement
issues that I've raised in the Power Point file below.
http://audiosystemsgroup.com/NCDXACoaxChokesPPT.pdf
Then take a look at
http://audiosystemsgroup.com/Toroid61Data-2.pdf
Virtually any reflection-based measurement (i.e., S11) will
give you VERY wrong answers for those chokes wound on #61 (and
also for the higher frequency coax chokes on #31 cores). It IS
practical to get good data using S21 (i.e., as the series
element of a voltage divider.
The Q-meter is fine instrument, but not many folks still have
one or know how to use one. As the Power Point shows, my
voltage divider technique is able to get pretty good data for
some pretty high Z parts with instrumentation of modest cost.
73,
Jim K9YC
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