On 7/5/2011 7:15 AM, Michael wrote:


Why do balun builders always use "enameled" wire? Won't regular
electrical insulated copper wire like they sell at Lowes or Home Depot
work? Since copper is copper what is the benefit of enameled wire
over other types of insulated wire? Also is there a benefit of using
solid copper wire over stranded copper wire to build a balun?

Michael Rawls
KS4HY

Because the windings on a balun is not just turns on a core. They are
transmission lines of a specific impedance. Wires of a diameter must be
a certain distance apart to make a line of of the desired impedance. If
the line is supposed to be 50 Ohms they need to be close together, too
close for the thick insulation on house wire. Stranded wire is harder to
wind on a ferrite core and maintain the spacing that is needed to make a
good balun. Just remember that baluns are not transformers in the
classic meaning of the term. They are made of sections of transmission
lines. For example a 4 to one balun is made of 2 100 Ohm lines that are
connected in parallel on one end, 50 Ohms side and in series on the
other end for the 200 Ohm side. The common mode impedance keeps one end
from seeing the other at RF frequencies. You can not see this with a Ohm
meter!

John W3JXP