[Elecraft] I Hate Winding Toroids

Sun Sep 7 18:47:00 2003

Tim,

I didn't have any toroid winding experience until my very recent build of my
K2.  I've read a lot of information on techniques, methods and opinions.  I
personally didn't find the winding part to be an issue at all but I can see
the advantage of your dowel tool to get the wire wrapped tightly to the
toroid without having to apply a death grip on it with two fingers.  The
difficult part for me was removing the enamel from the wire.  I initially
tried the solder blob method.  After trying this, I thought they must be
kidding! - this is a mess.  I then tried the torch method (lighter) on extra
wire to practice on.  I obtained about the same results.  Using the torch
method leaves residue that you have to take off with an abrasive paper.  In
addition, the enamal appears to be somewhat flammable and it is not really
possible to control how much of it burns off.  This can cause you to take
off too much and too close to the toroid and may cause a short on a bi-filar
type winding.

All though probably not recommended by most, I found that scraping the
enamel off and then tinning the leads worked much better for me.  The trick
here is to ensure that you lay the wire down on a flat hard surface and
position the knife blade at a 90 degree angle to the wire.  Apply very light
pressure while scaping and presto - comes right off without the heat and
inhaling enamel fumes.  You have to rotate the wire and scrape each side to
obtain a clean wire.  Do not try to scrap the enamel off with the blade at
an angle like you would if you were shaving the bark off of a stick.  The
blade will snag on the wire and you will knick the wire causing it to
break - sooner or later.  Good luck on your windings...

John - KI7V

----- Original Message -----
From: "Tim Payne" <[email protected]>
To: <[email protected]>
Sent: Sunday, September 07, 2003 2:04 PM
Subject: [Elecraft] I Hate Winding Toroids

> So, I came up with an easier, more consistent method of winding
> them.  Before, I used to stumble, by putting the ferrite
> in a vice, holding it in my hand, and several other failed
> attempts which I'm really too embarrassed to detail.
>
> I kept envisioning how it would be wound by machine.
>
> I never figured that part out, but came upon a simple economic
> solution.  A 50 cent dowel at the local hobby shop and a vice.
>
> The first problem to overcome was the correct diameter of the
> dowel. Too big and the toroid would flop all over the place and
> if too small, it would get stuck.  While I never came up with
> a scientific formula to determine the correct size, I sort of
> guessed the fit.  In this example, I found that when using a
> FT-37-43 (red) ferrite, a 3/16" dowel worked fine.
>
> I cut about a 3 1/2" piece of the dowel, tapered the top
> slightly (crudely) to allow for wire constriction as the
> toroid was wound.  I also played with a slight notch
> around the circumference for the more densely wound
> toroids.
>
> While winding, the area between the ferrite and the dowel
> would diminish quickly so do to the taper of the dowel, It
> was easy to slide the toroid up a little as necessary.
>
> I thought of using a piece of tooled, sanded plexiglas
> or metal as the form but felt that enamel chaffing might
> occur more than desired.  Wood being soft and cheap
> seemed more appropriate.
>
> You are also able to torque the windings slightly better
> to achieve a more consistent form.
>
> This is my first donation of my experiences with this
> group and hopefully it won't be my last.  One thing
> is for sure.  Whether you agree or not that the Elecraft
> experience is good or bad, it dramatically increase your
> enlightenment of electronic assembly and fabrication
> and the pride that you're not just an appliance operator
> anymore.
>
> If you want to see more, check out my web location
> for images of the Winding Form:
>
> http://home.comcast.net/~tim.payne/index.html
>
>
> Thanks Eric and Wayne for a great product !!!
>
> -Tim Payne
> -N9ABK
> -Eagan, Mn
>
>
>
>
>
>
> Tim Payne  --  [email protected]
>
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