[QCWA] baluns part 5

[Jeffrey D Angus]

Selecting the proper balun...

If you have a balanced tuner feeding balanced lines
directly, the choice of what kind of balun isn't that
critical.

However, if you have a coaxial tuner, i.e., unbalanced
input and output the choice of of a balun is important.
Especially if you're going to use a section of coax
between the tuner and the feed line.

A well designed wide range tuner _will_ make up the
oddities caused by an incorrect balun, but the tuning
will be finicky.

Having the correct balun will make the entire feed
line look, and tune, as a single item. Not as two
different sections at cross purposes with one another.

4:1 baluns are popular and work well. Into a 200 ohm
feedline. However, nobody makes 200 ohm feed line.
A better choice is a 9:1 balun with the 450 ohm window
line that is currently widely available on the market.

The MFJ Versa Tuner, for example, has an internal 4:1
voltage balun. But because the balun is connected
directly to the tuning circuit, it will work with 450 ohm
line nicely. You're just dealing with a built in initial SWR
of a little over 2:1 to begin with. But you do NOT have
a section of 50 ohm line between the balanced line and
the tuner adding it's own transformations that have to
be compensated for.