[AMPS] RE: Litz Wire

[Dave Bowker]

Litz wire (Litzendraht) is (not) created by simply twisting insulated
conductor strands together as described in the original posting.  The
insulated strands must be braided, i.e., transposed  a manner such that each
strand occupies all possible positions in the cable to approximately the
same extent over any given length of the cable.  The braiding must be such
that each strand passes from the center to the outside of the cable at
regular intervals.  This causes the magnetic flux linkages surrounding the
various individual strands of the cable to be essentially the same for all
strands over the total length of the cable.  By using a large number of very
fine strands braided correctly, and connected in parallel (only) at the ends
of the cable, the ratio of the AC resistance to the DC resistance of the
cable can be made to (approach) unity at the (lower) RF frequencies.

Each strand in the cable must always remain insulated from the other
strands.  Any breakdown of the insulation at any point in the cable destroys
the effectiveness of the entire cable

The practical limit for use of litz conductors is around 500 kHz, and it is
NOT effective or useful above approximately 2 MHz.  This frequency
limitation is due to irregularities in the stranding and the capacity
between individual strands which prevent the ideal conditions to be achieved
at higher frequencies.

73, Dave, K1FK
Fort Kent, ME



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