[TowerTalk] Loading Coils

[David Gilbert]

I remember that as well.  Well over $100 for even a moderately sized 
coil.  That's why I came up with the do-it-yourself 3D printed concept 
that I posted here a few days ago.  I can make exactly the coil I want 
(length, diameter, wire size, number of turns) for pennies within the 
same day.  In case anyone missed it, here's the version that has a very 
slight taper.  I also have a video that shows how to make a coil with 
uniform diameter, but to be honest I can't really think of a situation 
where that would be needed ... no coil we make is likely to be EXACTLY 
the inductance we calculate so we're going to be trimming or tuning anyway.

https://youtu.be/qAgF9Mzr8XM

The approach uses OpenSCAD (a free and easy to use parametric modeling 
application) to create the .stl file for the coil form, and the OpenSCAD 
code itself (which allows you to set the specific parameters for your 
particular coil) is available as a free download from:

https://www.printables.com/model/371698-air-wound-coil-form

3D printers are great for ham radio stuff like this.  I've always 
thought that every ham radio club should have one for the needs of their 
members.  Even a $300 (or less) printer would handle most projects and 
the filament is pretty inexpensive.  I have other videos on YouTube 
showing how easy it is to make VHF and UHF antennas for satellites (ham 
radio, weather maps, INMARSAT marine and aviation communications, etc) 
using 3D printed parts, for example.

73,
Dave   AB7E



On 8/4/2025 3:03 AM, Rob Atkinson wrote:
> The last time I looked into buying from B&W which was a few years ago,
> I was stunned by their prices on new coil stock.  They wanted hundreds
> of dollars for an airdux wire coil that might have been 6 to 12 inches
> long, 4 inches diameter and maybe six TPI, IOW your typical antenna
> coil.
>
> 73
>
> Rob
> K5UJ
>
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