If you use soft copper tubing as used in refrigirator ice makers snd isnt
necessary. Wind the coil on a round form a bit smaller than the desired end
result. Clamp one end in a vise inorder to have tension. When finished let
it expand to where it wants.
Then cut 3 lengths 1/4" polystyrene flat stock and notch at the desired
spacing. Do one at a time and notch for the pitch used. Insert in the inside
of the coil and epoxy in place. If the coil is going to be subject to a lot
of heat then use a different material such as fiberglass.
Carl
KM1H
----- Original Message -----
From: "Dan Hearn" <dhearn@air-pipe.com>
To: "Dan Hearn" <dhearn@air-pipe.com>; "Dennis Ashworth" <K7FL@arrl.net>;
<Amps@contesting.com>
Sent: Tuesday, November 20, 2007 4:37 PM
Subject: Re: [Amps] Winding large inductors
>
>
>
> Dennis, I have heard of people filling the tubing with sand to prevent it
> from kinking. I would think you could push or pull on the end of the
> inductor to adjust turn spacing. How about using small nylon cord wound
> with
> the tubing to approximate the spacing you want?
> 73, Dan, N5AR
>
> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]On
> Behalf Of Dennis Ashworth
> Sent: Tuesday, November 20, 2007 1:22 PM
> To: Amps@contesting.com
> Subject: [Amps] Winding large inductors
>
>
> I need to construct a 35uH air inductor using .250 copper tubing. D
> is around 5"; L = 10 inches. I can play with the dia & L a bit and
> still be in the Q ballpark I desire.
>
> Does anyone have a jig or technique they use to make such a coil
> while maintaining the turn spacing and not kinking the tubing? It
> needs to be "pretty" because of where it will be located :-)
>
> Thanks
> Dennis, K7FL
>
>
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