[Lowfer] Litz collection - long

[Mitch Powell]

Hi Bill:
I knew I had a collection of notes - so here they come, with credits
where I could find them. Now all you have to do is flip a coin ! !

Following are notes, e-mails, and comments as noted from Litzperts.

73
Mitch VE3OT

--------------------------------------------------------

To All from PA0SE

May I inject an item on a low-tech subject into the stream
of high-tech stuff that has been coming to us via the
reflector?

I know that soldering litz wire has been discussed
extensively lately but by chance I came across an article on
the
subject written by a professional that may interest you. It
relates to litz wire with strands covered by enamel.
Modern litz has a coating that dissolves in molten solder
and soldering  is no problem.

I found the article in the 1949 edition of ELECTRONICS
MANUAL FOR RADIO ENGINEERS  (McGraw-Hill).

I wish you and yours a happy and healthy New Year with
extreme DX!

73, Dick, PA0SE
JO22GD

                                     Soldering Litz Ends

                                      By EMERICK TOTH

The writer had occasion to design a receiver for aircraft using coils of
litzendraht wire. These coils ranged in diameter from 12 inches, wound
with litz of about 180 strands of number 38 wire, to little fellows
of 1/2 inch ID using 7/41 litz. Over 150 coils were involved, a total
of more than 300 coil ends, thousands of individual strands
that must be properly tinned and soldered. Careful tests were
made of the following three methods:
 (1)  Cautious removal of the silk and enamel from the coils end by
abrasion against a relatively soft high-speed rotary wirebrush.
 (2)  Heating of the coils end in an alcohol or Bunsen-burner flame
and subsequent plunging of the hot coil end into alcohol.
 (3)  Application of a small quantity of a paste of zinc chloride and
water to the coil end and heating with a soldering iron, immediately
followed by tinning with rosin-core solder while the resulting zinc
chloride and enamel mixture was still boiling. The silk insulation was
burned and stripped off by a very short exposure to a flame, and
subsequent wiping with a rag prior application of the zinc chloride.

 Method (1) was found to damage individual strands excessively, and
did not clean all strands in sizes of litz with many strands, such as
70/38 and 180/38.

 Method (2) was difficult to control. Insufficient exposure to the
flame resulted in the enamel not cracking off when the hot coil end
was plunged into cold alcohol. Overheating caused individual strands
to burn off. Even when satisfactory cleaning was obtained, the copper
was left so brittle that soldered coil end would break easily.

 Method (3) provides easy and effective tinning. The appearance of
the tinned end was neat and clean  after the residue of zinc chloride,
enamel, rosin, and solder had been wiped off while still hot with a
damp rag. The ease of tinning even 180/38 litz suggested that inside
strands were not properly coated. Several samples were cut in
cross-section but all strands appeared to be clean of enamel
and tinned.
 Samples were placed in a salt-spray chamber and subjected to the Navy's
standard salt-spray test for two hours. It was found that except for a
light accumulation of powdery salt the samples were in no way affected
by the test and all 300 coil ends were  processed as outlined in method
(3) above.
 Eighteen months after delivery, one equipment was examined which had
been in service in Panama for a year.  No trace of corrosion or any
other damage was found.
 Zinc chloride is very hygroscopic and should be kept in a suitable
well-stoppered glass bottle, with only as much paste prepared at one time
as is needed for a few hours use.


DE BONDT WERNER wrote:

> Hello Dick and all Lowfers Interesting article abt
> soldering litz-wire Dick .
> But If you don't like the
> professional way, then do the following:

> 1. Put an ASPIRIN (nothing else ) on the table .
> 2. Lay the litz-wire on top .
> 3. Push with the soldering iron on the wire , and solder

> I have used this method for many years with success
> Happy new year to all .   Werner ON6ND



How to solder rf litz wire

Your type of litz wire can directly be tinned with the soldering? Then skip
the following lines.

Among other things there is litz wire which connnot be tinned because
the strand isolation resist soldering:

Here is some advise for those who are not familiar with the handling of thi=
s
type=20
of litz wire. It is stranded wire but each wire is enameled to isolate it
electrically=20
from all the other wires in the bundle with temperature resistant lacquer.
Since=20
each wire is so thin (about numbers 40 to 44 AWG) it is out of question to
scrape=20
off the enamel of each wire with a knife in preparation to soldering. Just
remove=20
carefully about half of an inch of the silk covering of the wire bundle.
Then hold=20
the fine strand bundle into the flame of ethyl alcohol (spirit). Watch the
wire
become red hot and then imediately immerse into the spirit liquid below the
flame to cool off. The litz must be bright and shiny after this. This
procedure=20
cleans the wire and it is ready for tinning. Attention! Every fine wire
(strand)=20
of the bundle must be tinned. Better try a couple of times with some spare
wire=20
to get the knack of it.

Be safety - conscious ! Beware of the open flame ! Don=B4t start a fire!


Hint by Peter Stepponat



Soldering Litz wire. Firstly the Litz wire should be with a self fluxing
insulation, i.e.=20
one which will decompose with the heat from solder. If it's not self fluxin=
g
- you've
got a problem. The tip to get the litz wire to tin is to ensure that molten
solder is=20
applied to the the metalic ends of the individual strands within the wire.
This will=20
ensure that the strand heat up and the wire tins. Trying to apply the
soldering iron
directly to the enamel insulation won't work. For large wires, a small
solder pot is=20
ideal. Solder can be easily melted on a domestic stove, or even in a very
hot oven.=20
Simply dip the litz wire into the solder pot containing the molten solder
and the wire=20
is tinned is a matter of a few seconds. No scrapping of the separate strand=
s
is required!

A.R.C., April 1993


If you have to remove a turn from your Cosmos PTO:=A0 Take an aspirin
tablet and place it under the litz wire. Get a ball of solder on a hot
soldering iron and use it to press the litz wire into the aspirin tablet.
The wire will be stripped and tinned all in one operation.


The Litz wire is wound with no spacing based on the results reported in
reference 6. It should be noted that the Litz wire is about 7 times more
expensive than ordinary copper wire. I used Strip-Eze to remove the
insulation from the Litz wire for soldering  (W9RB)


http://www.dartmouth.edu/~sullivan/litzwire/litz.html


I had several connections to make today using 729 strand litz wire and
it took me no longer than 10 minutes to prepare and solder the ends.
Using the technique that I described before on here. Spread the ends
out, dip in paint stripper for a few minutes, then brush off the
disolved enamel with a tooth brush, wipe and clean  with white spirit,
then twist the wire to get it back to its original diameter and solder.
The perfect connection, patent applied for, it seems no one that I have
spoken ever thought of the idea.
Most professionals follow the clumsy time consuming solder pot procedure
and radio amateurs dont have a clue how to handle litz.
G3KEV


Mal G3KEV wrote

>>>>>>>>Sent: 12 September 2001 01:23
Subject: LF: Tip
Litz wire.

To solder litz wire of the variety used by Decca.
Strip off about 10 -20 mm of the plastic/cotton covering
Dip the exposed end in paint stripper for a few minutes.
Use a tooth brush to remove the disolved enamel insulation, dip end in
white spirit and wipe.
Solder the exposed bare copper end in the usual way.
Using this method no special tools or solder pots are required.
This procedure is not required for the self fluxing litz type wire.
G3KEV <<<<<<<<<<<<<<<<<<<<<<<

Thanks for the tip Mal. I tried it today and it works beautifully.
I found it necessary to give the wires several dips in the paint stripper
and it helps if you fan them out. No more burnt insulation or un removed
enamel.

Regards

Mike GW4HXO.




Litz wire
Before commencing the procedure to solder litz wire as in TIP 1

Remove the plastic from an appropriate sized electrical block
connector(strip) and slide it over the end of the wire to be soldered
back up the wire enough to be able to solder the end properly.

After the soldering procedure has been completed and the wire end is
still hot. pull the connector gently back off the wire end and this will
give you a nice neat wire end and avoids the wire being splayed out.

If desired keep the connector on the end of the wire but pull it back so
that only half the connector is used, this leaves the other half to
insert what ever wire you want to join to the litz.

G3KEV
















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