[TowerTalk] TowerTalk Digest, choke / balun design needed

[Earl Morse]

Check out W8JI

http://www.w8ji.com/windom_off_center_fed.htm

Most of the OCF designs seem to be a compromise to get a multiband antenna with a single feed and no tuner.

If you are going to go with OCF for just 30M only you could optimize your balun for best match at 10 MHz rather than choosing a design that is good from 1.5 MHz to 30 MHz.

Once you figure out the OCF dimensions and know the feed point impedance for the antenna that you put up on 10 MHz then design the balun for that frequency/impedance and your desired power handling capability.  Baluns get a little harder to design when they have to cover wide frequency ranges but are pretty straight forward at smaller ranges of frequency.

Earl
N8SS



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Message: 3
Date: Mon, 27 Apr 2015 09:50:39 -0400
From: Alex Malyava <alex.k2bb at gmail.com>
To: towertalk <towertalk at contesting.com>
Subject: [TowerTalk] choke / balun design needed
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	<CAMHr7dLR-vZ_6sfHLVC_iZ4Eo3dwPPYxsCa=K0PDz_v57e65MA at mail.gmail.com>
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What would be the bestest design for choke or balun to be used with dipole
or OCF dipole?
Like what type of core, number of turns or number of beads?

I need an antenna for 30m band, and my very first intention was to go with
simple dipole.
Next idea was to put OCF dipole to use in on more than one band :)

So far, for a regular dipole, I came up with "1:1 Ruthroff voltage balun
design" described in http://vk6ysf.com/balun_1-1.htm page.

OCF is what I got stuck with...
I know that OCF dipoles need something more than just a balun...
What should I use?
A bunch of beads over the coax? Some balun + beads?

Alex K2BB


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