BTW this pattern http://www.balundesigns.com/catalog/anechoic2.jpg of
no balun vs. with balun
http://www.balundesigns.com/catalog/anechoic1.jpg is far from true.
Even ARRL antenna handbook took it out years ago. Original source is
article in QST ,April 1980 by WA9NEW,
http://www.arrl.org/files/file/Technology/tis/info/pdf/8004019.pdf
Error was probably due the fact that measurement was taken at 1.6 GHz.
I have tried to replicate this BAD pattern at Cushcraft Anechoic
chamber back in 1999 at 450MHz and all I got was a bit squinted (few
degees to the side of "hot" half of dipol) number "8" dipol pattern
without Balun.
Even DXengineering uses similar pattern
http://www.dxengineering.com/images/examples/BALUN-2.jpg for marketing
their new line of Comtek baluns.
73 Danny E73M
-------- Original Message --------
Subject: [RFI] Balun designs chokes
Date: Sun, 08 Jan 2012 14:14:52 -0600
From: e73m@e73m.com
To: <rfi@contesting.com>
Hello,
did anyone measured balundesigns.com chokes. I have tried to make
replica with FT240-K core and wound as on pictures but simple S21
measurements shows poor response below 21MHz, nowhere near their
published charts.
It looks like their core is a bit different then then standard FT240-K
core as used in Comtek/DXengineering chokes.
73 Danny E73M
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