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@contesting.com> On Behalf Of David Gilbert
Sent: Wednesday, January 18, 2023 19:31
To: towertalk@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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