[Elecraft] Balun inside K2 ... digest #200 msg 1

[John Crux]

I have built two LDG AT11 tuners. I would not like to try putting a
half decent balun into either my K2 or into the standard LDG case, or
even into the home brew case I used for the first AT11.
I have made several 4:1 baluns. One was on a T-200 powdered iron core
and I made it for use with my AT11 by a UK foundation licensee, at his
legal limit of only 10 watts RF. It was marginal on 40m and useless on
80m (not enough inductance ?)
So I swapped it for the humongous ferrite core balun (SIX 2.4 inch
ferrite cores) the partly assembled guts of which I found on the
Dayton flea market. If Jerry Sevick (see below) is right this item
will probably handle 20 kW. Small it is not. Maybe an overkill for
10w. But it sure works down to 160m !

Before trying to squeeze a tiny balun into either the K2 or the LDG,
I suggest asking if your journey is really necessary. From the
literature (mostly the article by Jerry Sevick W2FMI in CQ, November
1993 page 50) its not trivial getting adequate performance, especially
from a small enough-to-fit-the-space toroid.
Greater flexibility (and efficiency) is probably achieved by using an
external balun whenever you need one. Cut your losses. There is a CWS
ByteMark kit with a 2.4 inch ferrite core that should do the trick. Or
I'd use a large powdered iron core, like a T-300D. Small is not always
beautiful ..
P.S. Wayne & Eric - assuming the KAT-100 will be designed to fit into
the EC-2, there should be room for a nice BIG balun, if anyone wants
one.
John G3JAG
K2 #609 into a few feet of RG-8, a Centaur balun (2 stacked ferrite
cores) and lots of ladderline. Over 250 countries worked with a 40m
dipole.