Could some please point me to a good explanation of how litz wire works?
As frequency rises the current through a wire tends to flow only close to
the surface, the so called skin-effect. On 136kHz the skin-depht is about
0.17mm (for copper-wire), so for any wire thicker than 0.35mm there will
flow little or no current in the centre of a the wire. For that reason it
is much better to use a number of thin wires in parallel instead on a
single thick wire.
Litz wire contains a number of thin wires that are isolated from each
other, reducing the skin-effect and thus allowing to construct high-Q coils
with a relative small diameter wire.
If you want to know more or learn about the specifications have a look at :
73, Rik ON7YD