[QCWA] Baluns part 10

[Jeffrey D Angus]

I'm going to talk about inertia this time.

Despite the fact that the prevalent balanced line sold
these days is 450 ohm nominal impedance, most tuners
with built in baluns use a 4:1 voltage type.

As I had mentioned previously, this isn't TOO much of
a problem as the balun is connected directly to the
tuner network.

However, most HF rigs with built in tuners and the
tuners without an internal balun require the use of
an external balun.

The tuner manufacturers offer a 4:1 balun. Some
also offer 4:1 choke (current) type baluns.

This is called inertia. A reluctance to change. Despite
the benefits of using a proper balun ratio and type.

Oddly enough, Beldon and other coax manufactures
do not offer 112.5 ohm Coax which would be the
preferred impedance to use with a 4:1 balun and
450 ohm balanced line. Equally problematic is the
proper winding media for the balun core. I.e., 225
ohm transmission line. In the case of two #16 AWG
wire, it would need 0.110" spacing between them.

Did I mention 112.5 ohm coax? *grins* It does kind
of exist. It takes a 1/4 wavelength of 75 ohm coax
between the 50 ohm source and the 112.5 ohm load.

Effective, but kind of a problem when you want to
have frequency agility that doesn't include swapping
out sections of coax every time you switch bands.

Jeff-1.0
wa6fwi