A couple of people have pointed out that there are in fact "balanced
tuners" which are designed to work with balanced feedlines only and
which are described as being without baluns.
Well, I don't want to be accused of splitting hairs, but it seems to
me that it's just a matter of terminology.
As I see it, you simply cannot go from an unbalanced line to a
balanced line without a balun, period. Any device which has an
unbalanced input and a balanced output is ipso facto a balun.
There are two functions which a balun can perform, and that seems to
be confusing the issue. First is transformation from unbalanced to
balanced (and vice versa). Second, since the device actually is a
transformer, you can use it to transform impedance by putting a
different number of turns on one side of the transformer as compared
with the other. Or you can use the same number of turns and have the
same impedance on both sides, aka a 1:1 balun. The impedance ratio
of a balun is equivalent to the perhaps more familiar turns ratio of
a voltage transformer (and there are 1:1 voltage transformers, too,
generally called isolation transformers or, if memory serves,
autotransformers.)
So... it seems to me that if an antenna tuner is designed to work
only with a balanced output, then it is by definition a balun in and
of itself, albeit a "tunable" balun.
73
Marshall Emm
AA0XI/VK5FN
aa0xi@mtechnologies.com
http://www.mtechnologies.com/mthome
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