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From: "Stuart Rohre" <rohre at arlut.utexas.edu>
To: <casey.jay at gte.net>, <elecraft at mailman.qth.net>
Subject: Re: [Elecraft] Baluns for KAT1
Date: Fri, 25 Jan 2002 19:40:14 -0600

Donn,
when I went to the Elecraft web site, the links (URLs) did not automatically
appear in the web page header, so do these steps:

First go to <elecraft.com>  There, Select the heading "Tech Note Articles"
on the left of the page.

Next, select from Articles, "K1,K2 Application Notes".

 Next, on that App. note page, select "Balun Transformer construction
links."

On the Baluns page, select the "1:4 Balun Picture"  You will see a photo of
the FT 114-43 core (available from Bytemark who are linked below as Balun
kits).  On this core, are the six turns of Radio Shack speaker cable, with
copper and silver wires in clear plastic.  Note this is the 16 ga. Radio
Shack wire, not their larger ones.

Now here is what is NOT shown, (see the four wire ends.)  On the left is the
start of the first winding, with a silver wire to the left, side by side
with a copper, which is hard to see because it is behind the common solder
joint between it and the silver wire of the finish winding on right.

The silver wire to extreme left comes out to one binding post, and also to
the center of the coax socket you use.  The copper wire, of the start from
the left, solders to the silver wire of the finish, and this joint wire thus
formed, goes to the shield side of the coax connector.  Now, you are left
with that finish winding copper wire on the right, and this goes to the
remaining binding post.

The binding posts will be the 4:1 step up connection for twin lead.  The
coax jack goes to the K2, by a short coax jumper, or you can install it
inside the radio and hook up to the output of the internal antenna tuner.
Some K2's have accessory items that take up the room in the case, thus you
may find it convenient to build the balun onto a simple L bracket of
aluminum or steel, with the two binding posts mounted on one face of the L
and the coax connector on the other face.  The balun can be glued to the
bracket, or simply supported from the binding posts and coax jack.

The other balun links on the page either did not work or describe much
larger cores than you need.

Also, the Bytemark balun kits are for 100 watt baluns, thus are too large to
fit the radio well.  They would work fine, of course, and are priced
reasonably, but require winding a core with copper wire, and are more work
than this balun in the photo.  Note this simple balun works from 80m to 10m,
and a local who built one reports his did as well.

This is a good project in simple toroid winding so I encourage you to do it,
and let me know how it turns out.
The nylon ties seem like a good way to hold the start and finish to the
core, but string or nylon fishing line would do it as well, if you can tie
fishing knots!  (That would be the hardest part of this 6 turn balun!!!) HI!

GL and 72,
Stuart K5KVH

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