[Lf] [Fwd: LF: RE: litz wire]

[Andre Kesteloot]

James Moritz wrote:

> Dear Bill, LF Group,
>
> I have a considerable amount of Litz wire recovered from a scrap Decca
> loading coil - as has been said, there is more than one type of enamel
> used. The newer type (usually orange, red or pink) is self-fluxing, which
> is easy, but the type I have is a dark brown enamel that seems impervious
> to any chemicals I have tried, including Nitromors and other types of paint
> stripper. The alcohol burner method removes it well, but with 729 strands
> it is not really practical to burn the insulation off all the strands
> without causing a raging inferno! Similarly, the asprin method works to a
> degree, but it only cleans some of the strands with thick litz wire, the
> residue makes it difficult to repeat the process to clean the remaining
> strands, and the smoke generated is horrendous!
>
> The method I have used is to burn the insulation off with a blowtorch - but
> to do this without burning away a lot of the strands some care is needed.
> First, strip about 70 - 100mm of the plastic sheathing, and un-twist the
> end 25mm so that the strands are like a small paint brush. Then, tightly
> wrap this end in a strip of copper foil, such as might be peeled off a PCB.
> Wrap the strands next to the plastic sheathing in another piece of foil,
> and clamp in a metal clamp or vice - this acts as a heatsink to stop the
> sheathing melting. Then heat the foil-wrapped end with a blowtorch, taking
> care to apply the flame only to the foil, not the strands. The foil gets
> red hot, and the enamel burns off with an oily flame. After it has cooled,
> unwrap the foil - it looks like the enamel has just turned black, but the
> residue can be removed fairly easily by dipping it in water and brushing
> gently with a toothbrush, or rubbing the strands together like cleaning a
> paintbrush, to leave clean copper. Then it can be tinned in the normal way.
>
> I can't say it is an easy method, but it does work with otherwise
> indestructible enamel, and after a few practice runs it gave me
> satisfactory results for my loading coil.
>
> Cheers, Jim Moritz
> 73 de M0BMU