Tinning Litz wire

[Chris Wilson]

I have a temporary loan of a drum of heavy Litz wire. I am winding a loading coil fo an LF transmitter with some of it, but tinning it has defeated me. I do not have a solder pot (but might be interested in buying one if was quite cheap), so have used liquid flux and a hefty iron on full heat. The wire strands just blacken and will not accept solder. Am I right in thinking a caustic based paint stripper like Nitromors might remove the enamel, or even boiling caustic soda?


Thanks.

[David G4EBT]

As often as not, these days litz is solderable, but generally a solder pot is used, with the wire dipped in flux then in the solder pot for several seconds during which time the heat of the solder pot carbonises the enamel. If the wire you have isn't solderable, then maybe nitromors might remove the enamel, but if the individual strands are of a gauge that they can be scraped clean that might be a better bet, but I guess the wire you're using may have just too many strands for that to be practicable.

Obviously if each individual wire isn't successfully tinned, then it negates the whole point of using litz.

In days of yore, when attempting to wind RF coils with Litz, I never had any success - the 'urban myth' said 'dip it in meths and set fire to it' at which point it just vaporised.

There are a couple of videos at these links you might like to view - they're not very good, but might give an idea. They both use solder pots though, but if yours is just a one-off job, maybe you could simply melt solder into a small stainless steel container on say a camping stove or using a gas blowlamp. (Poundland and the like sell small stainless steel containers for use in the kitchen):

https://www.youtube.com/watch?v=TntXWct7a3U

https://www.youtube.com/watch?v=auAlNe1jA64

There's a PDF here which might be of help, entitled 'Termination Methods for Litz Wires':

http://www.google.co.uk/url?sa=t&rct...601,bs.2,d.ZGU

Hope that helps a bit.

Best of luck in your endeavours Chris.

[Andrewausfa]

Our cousins across the pond use an Aspirin. Not tried it myself but the method is to lay the wire to be soldered on top of the Asprin, put a blob of solder on your iron and apply heat to the wire. The enamel is removed and the wire tinned.

Andrew

Improvise a solder pot?
Another thought, wrap tightly with tape, cut, flux and tin. At least all the ends will be soldered.

[Radio Wrangler]

You need to get heat into the copper core, and the varnish just insulates it while the copper transports what little heat gets in to it.

I found the trick with solder-through varnish was to wet the iron and get the ends of the wires into the hot blob of solder.

This way heat has only one direction of flow away from the heated area, and the heat transfer is solder to copper at the face of the cut end.

With single tsrand wires of all sorts of gauges, it makes quite a difference.

David

[kalee20]

Depends if the enamel is solder able, as others have said.

A solder pot at 400 deg C will do the job if so, you need the surface of the solder to be clean, and you also need a bit of flux. Be prepared to sacrifice half an inch at the end. Once the enamel has started to give way, heat gets into the wire much better.

If the wire is non-solderable, things are much harder. Nitromors won't do anything. Molten caustic soda will, though this is not to be considered lightly! Equip yourself with an emergency kit first, something to neutralise it if you get splashes (lots and lots of a weak acid - lots because you want to be sure you've neutralised all the splash, and weak because with excess acid you don't want it to be strong).

[joebog1]

With origional Litz wire you burnt off the silk or cotton covering first, using a pair of pliers or heavy tweezers to prevent "burn back" along the wire, then cleaned off the burnt enamel/silk/cotton with steel wool, or colour paper, AKA as 2000 grit automotive emery paper. then twist and tin the conductors in the conventional manner.

You explained you "borrowed" the roll of Litz wire, WHERE does one buy it today?
Especially DSC ( double silk covered) apart from wrecking old IF transformers??

Joe

[Radio Wrangler]

It's still used in a number of specialist applications, but manufacturers no-longer see it as a catalogue item. The prices will take your breath away. There are so many possible varieties that it's treated as made specially to order.

If I had to buy any in less than industrial quantities, I'd get in contact with the Scientific Wire Company, London.

David

[Ian - G4JQT]

I was told to set fire the the insulation and quench it in meths.

You need your wits about you, and probably best to blow it out just before you quench it so as not to ignite the meths!

In practice this isn't as dangerous as it sounds (in my experience anyway) and you get a nice solderable end.

Ian

[Phil G4SPZ]

I recently repaired a transistor portable where the windings on the ferrite rod aerial were wound with three-core Litz wire. The rod had slipped and snapped one of the Litz wires leading to the PCB.

I scraped the enamel from each strand using a Stanley knife blade, then twisted the cores together and soldered them in the normal way.