[Lowfer] Re: Litz wire

[James Moritz]

Dear Lowfers,

Last time I spoke to Derek at the Crawley club (a few months ago) they had 
sold all the plastic covered litz, but stll had some with a single silk (or 
nylon or whatever) wrapping - this works fine for loading coils, but I'm 
not sure if it would last long exposed to the elements in a loop.

For lengths of 10m or so, it is quite easy to make your own litz using 
enameled wire and a reversible hand drill - cut three lengths of wire, lay 
together in a straight line where they won't get tangled, attach one end to 
something solid and spin the other end round in the drill until you have 
several twists per inch. Repeat twice more, and then twist the 3 bundles of 
three together in the opposite direction - you now have 9 strand litz wire. 
Repeat the process with 3 x 9 strand bundles and so on, reversing the 
twisting direction each time, for 27, 81, 243, 729 strands, by which time 
you might have got bored! Try a short length first to get the idea. The 
result works just like the real thing. The first stage is a tedious process 
for very fine wire sizes as used in proper litz, but is much easier if you 
use about 0.2mm wire. This is not as good for reducing RF resistance, but I 
found it still doubled the Q of some filter coils I made for 136kHz.

Cheers, Jim Moritz
73 de M0BMU