[Lowfer] RE: litz wire

Tue, 14 May 2002 22:00:21 -0700

No.  It has to do with skin effect.  As the frequency increases, the
penetration of the current flowing gets closer and closer to the surface of
the wire - only.  At dc, the current isdispersed fairly evenly through the
entire area of the conductor.  At very high (UHF) frequencies the entire
current will flow in a small area near the surface.  So, Litz wire has a
huge surface area with rspect to the total area, thus the lower ac
impedance.

73s

Don Davis   AD6PB

----- Original Message -----
From: "Michael Silvers" <[email protected]>
To: <[email protected]>; <[email protected]>
Sent: Tuesday, May 14, 2002 4:50 PM
Subject: [Lowfer] RE: litz wire

> Hi Bill & Group,
>
> I believe why Litz wire has such a low AC resistance
> is because each strand is insulated and when soldered
> together you get the parallel resistance of each of
> the strand of insulated wire.  With uninsulated,
> stranded wire you may have the same current carrying
> capacitiy but you more than likely have a higher
> resistance because all the strands are in contact with
> one another & the current path will be through all the
> contacts that offer the least resistance but better
> than solid wire because of the increase perimeter
> length.
>
> If you know the particulars of your type of Litz wire,
> looking on http://www.mwswire.com/insspec.htm may
> offer some help to what method will be required to
> strip your type of wire.  For example, the polyimide
> type insulation will be impossible to strip with a
> soldering iron, thermal class 240�C.  Methylene
> chloride is your best bet.  The 180�C thermal class is
> solderable but with large wire diameters may still be
> difficult with a soldering iron.
>
> 73 de Mike KB6WFC
>
> --- "Ashlock,William"
> <[email protected]> wrote:
> > Mal and LF group,
> >
> > Thanks for all the comments on how to strip the Litz
> > wire. I'm continuing to
> > experiment and last night I placed a sample of the
> > wire in my paint stripper
> > for an overnight test. This morning the color had
> > changed from a red to a
> > typical bare copper color, but a check of the
> > conductivity indicated there
> > is still some insulation remaining. It's back in the
> > stripper at the moment
> > for another dose. My conclusion is that this
> > stripper is too weak to handle
> > the job. Typical of most dangerous products on the
> > market these days, it's
> > probably been 'watered down'.
> >
> > Mal, I'll check the ingredients tonight and see if
> > Methylene dichloride is
> > one of them. Thanks for this.
> >
> > BTW, with all due respect, I don't buy your: "3mm
> > litz wire is marginally
> > better than normal 2.5mm stranded insulated wire the
> > advantage is small", if
> > you are talking TX loops (which may not have been
> > the case).  My TX loop
> > measurements indicate the Litz would be 2.4x lower
> > in Rac, separate from the
> > soil loss, which runs 0.22 ohms (dry) on my 50'/50'
> > loops. I should have a
> > complete table of many TX loop conductor
> > configurations with Rac totals,
> > including soil loss from <0.40 (4xlitz) to 1.4
> > (single #12), completed in
> > about a week.
> >
> > Bill A
> >
> >
> > Hello Bill and all
> >
> > To remove the enamel from litz wire I use paint
> > stripper called nitromorse.
> > Remove all the cotton/plastic insulation from the
> > cable end to be soldered
> > to expose the multi strand enameled wires. Brush the
> > end of cable with a
> > tooth brush to separate the strands and flatten out.
> > Use the tooth brush to apply the paint stripper to
> > the splayed out cable
> > strands, making sure it gets to all the strands.
> > Leave for about 10 minutes
> > or more, then brush away the disolved enamel. I
> > carry out this process twice
> > to ensure that all enamel has been removed. The
> > final job is to wash the
> > exposed copper cable  end with turps etc using a
> > cloth, then start
> > soldering. I strip back about 1 inch of the cable
> > end.
> > I have used the above procedure a number of times
> > and it works well. Paint
> > stripper and a tooth brush are readily available.
> > This method is also
> > economical on solder, no need for special tools like
> > solder pots and bunsen
> > burners.
> > Any good paint stripper would do. My contents label
> > says the stripper
> > contains 5 - 20 percent
> > Methylene dichloride, it does not say what the rest
> > is.
> > This is dangerous stuff to get on skin, eyes etc and
> > brush away from you so
> > that it does not flick into your eyes or skin.
> > The container/can specifies what precautions are
> > nessary for use.
> > I find although 3mm litz wire is marginally better
> > than normal 2.5mm
> > stranded insulated wire the advantage is small
> > compared to the effort
> > required to solder and weight considerations,
> > especially for large loops or
> > horizontal wire antennas. I also have noticed since
> > winding my 0.5 mH
> > loading coil for the vertical with 3 mm litz wire it
> > is more critical to
> > keep on the nose at resonance, possibly because of
> > the higher Q than the
> > previous 2.5 mm multi strand insulated copper wire.
> > I hope these observations help you.
> > My current 90 metre perimiter loop uses 2.5 mm
> > insulated wire. I use it for
> > RX only and as said previously I have to throttle
> > the RF gain back on even
> > the very weak signals. I do not use any preamps only
> > the RX or Level meter
> > SPM 12. I cannot see any advantage using litz for
> > this purpose.
> > To use the loop on TX there would be an advantage
> > using litz but probably
> > the db gain would hardly be noticeable.
> > Very small loops on LF like 1 metre square etc might
> > be a different story,
> > but this does not apply in my case.
> >
> > 73 de Mal/G3KEV
> >
> >
> >
> >
> >
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