You are quite correct. My favorite tuner of all is a link coupled
balanced tuner, and it is L B Cebik's favorite too - low loss and can be
configured to match just about anything - series tuning for low
impedances or parallel for higher impedances. I have built many over
the years. No balun required anywhere. If I were able to bring
ladderline into the shack, I would have one of my old balanced tuners
with the plug-in coils to match the transmitter to the ladderline - but
I can't do that (don't ask!), so I use resonant antennas fed with coax
and clean up any required additional tuning with a KAT100.
But, one must admit that the KAT100 does offer a lot of convenience to
the operator, even though it has some drawbacks - it is not balanced,
and for those who are fortunate enough to bring ladderline into the
shack, it can be used with a balun. It is a workable solution as long
as some cautions are observed to minimize the loss. One cannot defeat
the laws of physics, but for those who must use an unbalanced tuner and
a ladderline fed multiband antenna, the KAT100 followed by a balun may
be an acceptable solution. Adjust the feedline length so as to provide
a decent feedpoint impedance at the balun without a lot of reactance,
and use a current type balun (a voltage balun just will not work well in
this application), and one can get on the air - it certainly is better
than no antenna at all.
73,
Don W3FPR
Goody K3NG wrote:
Using any balun with an unbalanced tuner to feed balanced line can be
bad news (your mileage may vary, standard disclaimers apply). Under
highly reactive loads, a balun used like this can become quite lossy.
There's a couple articles in publications and on the Internet on this,
but Cebik's article is one that comes to mind (
http://www.cebik.com/link/l-bal.html ). It's better to run a real
balanced tuner like a Johnson Matchbox, the MFJ Balanced Line tuner,
or others, if you can.
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