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 2400C. Methylene
chloride is your best bet. The 1800C 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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