[QCWA] baluns part 3

[Jeffrey D Angus]

The other type of balun is called a choke, or common mode
type.

(1)-uuu-(2)
(3)-uuu-(4)

Where terminals (1) and (3) are the input and terminals (2)
and (4) are the output.

The first type of choke balun was made with 10-15 extra
feet of coax coiled up in a circle where it connects to the
antenna.

The next step was in using ferrite to increase the efficiency.

There are two very important things to remember.

First, they are, by nature a 1:1 balun for a single coil, and
secondly they require not only a transmission line, but the
correct impedance transmission line.

Side note: For a 1:1 50 or 75 ohm choke balun, the easiest
way to get a 50 ohm transmission line is to use a piece of
coax. Using twisted pairs of wires is problematic as about
the lowest impedance you can get with two wires, side by
side is 80 ohms or so.

Jeff-1.0
wa6fwi