[TowerTalk] Litz wire

[Jim Lux]

----- Original Message -----
From: "Tom Rauch" <w8ji at contesting.com>
To: "Jim Lux" <jimlux at earthlink.net>; "Phil Camera" <kb9cry at comcast.net>;
"William Q Meeker" <wqmeeker at iastate.edu>; <towertalk at contesting.com>
Sent: Monday, March 14, 2005 8:14 AM
Subject: Re: [TowerTalk] grounding radials: solid or stranded?


> > The real question is whether this is practical or
> worthwhile at HF (>3 MHz)
> > frequencies.  It's certainly worthwhile at 60 Hz (HV
> transmission lines use
> > "bundles" rather than single strands to reduce series
> inductance (as well as
> > improve HV breakdown)).  It's also probably worthwhile at
> tens or hundreds
> > of kHz (as in switching power supplies, where they do use
> Litz wire in
> > transformers).
>
> http://www.w8ji.com/skindepth.htm
>


Ah yes.. but manufacturing technology has advanced quite a bit since the
days of Terman.  It's all well and good to assert that 1000kc was the
practical limit in Terman's day.  However, I wonder (not too much, but just
curious) what today's practical limit might be.  There's a push to higher
switching rates in power supplies and magnetics design (including conductor
layout) is a big part of the design.

As far as hams go: Hams, in general, aren't particularly concerned about DC
efficiency (except if you're battery powered) and we're unlikely to be
agonizing about eking out the last percent of efficiency in the power
supply.  And, given the fairly high cost of Litz wire, it's unlikely to be a
good engineering solution for lightning protection or grounds.

However, maybe high performance litz wire might be just the ticket for a
high Q loading coil on 80, although, I suspect that just making a bigger
coil out of silver plated tubing might be cheaper and more rugged.

It is good to go and reassess some of the "wisdom of the ages" periodically,
in light of new technology and materials, as well as better theoretical
understanding.

Jim, W6RMK