[TowerTalk] DIY Air Wound Coils

[W7TMT - Patrick]

One other trick that may or may not apply depending on your wire...

I was using either tin plated or enameled wire. Since I didn't need large quantities I ordered it in 1 pound spools. I found that I got better results and much more even wire to wire spacings if I left the wire on the spool rather than unrolling it. By positioning the spool such that the wire was unwinding off it and on to the coil form "in the same direction", one can take advantage of the existing curve in the wire as it just gets transferred to the coil form. Also gives you something to grip rather than the wire itself.

Before I stumbled on that the first couple of coils didn't have very even spacings between each turn.

Patrick

-----Original Message-----
From: David Gilbert <ab7echo at gmail.com> 
Sent: Wednesday, January 18, 2023 20:31
To: W7TMT - Patrick <W7TMT at outlook.com>; towertalk at contesting.com
Subject: Re: [TowerTalk] DIY Air Wound Coils


I could add another four slots in the form for a total of eight. You wouldn't need to use them all on smaller coils, and if you used them all on larger coils it would be easy to just turn over whichever strips you didn't want to leave in, such that their slots faced the form.

It would also be possible for someone to put a spacer (almost anything would work) under a turn as the coil was wound so it would stick out to make it easier to make a tap on close wound coils.

73,
Dave   AB7E



On 1/18/2023 8:59 PM, W7TMT - Patrick wrote:
> Dave,
>
> Very cool implementation with the 3D printer. I've wound several sets of coils for shorten dipoles supported on pairs of telescoping fiberglass windsock poles. I used the similar, but less sophisticated technique described by AD5X here:
>
> http://www.ad5x.com/images/Articles/CoilRevB.pdf
>
>  From my experience with larger diameter coils, you may want to provide notches in the form to allow installing extra temporary support pieces that are used during the winding but then not glued onto the coil. I found that on the 3.5" diameter coils I wound for my 40M dipole that the larger diameter resulted in very noticeable flat spots in the windings between the four main supports. Adding the temporary supports between, and then just not gluing them resulted in a nice round coil.
>
> Flats may not affect the inductance, I don't know. But the rounder units just looked better to my eye.
>
> 73,
> Patrick, W7TMT
>
> -----Original Message-----
> From: TowerTalk <towertalk-bounces at contesting.com> On Behalf Of David 
> Gilbert
> Sent: Wednesday, January 18, 2023 19:31
> To: towertalk at contesting.com
> Subject: Re: [TowerTalk] DIY Air Wound Coils
>
>
> This should definitely be feasible.  My example was really basic ...
> just a cylindrical hole with a rectangular slot on top of it that only infringes on about 40% of the cylindrical hole.  The remaining 10% provided the "snap".  A better approach to avoid glue would be a tighter fit with a ramped entry.  If the grips were freestanding and not slots that should work well.  Maybe I'll play with it and update the files.
>
> And although I used four bars, I think two might be sufficient based upon the coils I've built with #14 wire.
>
> 73,
> Dave   AB7E
>
>
>
> On 1/18/2023 6:15 PM, Brian Beezley wrote:
>> "My final choice was slotted acrylic bars for strength, water and UV 
>> resistance, and ease of solvent gluing the wires in place."
>>
>> Grant, after seeing several neat coil form designs in the style of 
>> Air Dux, I've been wondering if a precisely shaped groove might hold 
>> the wire reliably without glue. I imagine it snapping into place with 
>> a satisfying sound. I suppose this would work well only for a single 
>> wire gauge.
>>
>> Brian
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