[Boatanchors] Making coils

[Ron]

Hi Kees

I use multistranded wire for the switching power supplies that we design
here. Although it is only used to 100 Khz it does lower the series
impedance due to skin effect and keeps the coil cooler.
In your design , you will need to use wire no larger than twice the skin
depth.
---
Ron

Sandy and Kees Talen wrote:

> I'm playing around with some homebrew RF coils, RF
> transformers, etc and will put together a coil winder in the
> near future.
>
> My question is about wire. I have plenty of magnet wire up to
> #38AWG (from good ol' swapmeets), however, the earlier
> aplications used Litz wire but the "modern" (60's) JW Miller
> coils seem to use magnet wire. What are the advantages ?
>
> Since the Litz wire is multistrand, the surface area is increased
> which should improve it's capabilities at higher frequencies
> due to "skin effect", the coil "Q" may be higher because of this,
> and since it's not "round" it would lay in place better. Any other
> reasons ? Is the main reason for the pattern winding to keep
> the turns in place ? In other words, if you were winding on a
> spool, you would be OK by just winding uniformly ? The
> drawback would be finding the small stuff at a reasonable price.
>
> Magnet wire is cheap, might require the use of bobbins to get
> it to stay in place (although JW miller solved this with enough
> adhesive), and maybe multiple strands of #38 has the same
> effect as Litz wire. Would it have to be twisted ? Is the only
> reason for the winding pattern to keep turns in place ? Any
> other comments ?
>
> 73s  Kees K5BCQ
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