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Re: [TowerTalk] Loading Coils

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Loading Coils
From: David Gilbert <ab7echo@gmail.com>
Date: Sat, 2 Aug 2025 14:08:47 -0700
List-post: <mailto:towertalk@contesting.com>

I believe that is likely to be a more efficient approach than using an inductor.  It is possible to make air wound inductors with pretty high Q and not much loss, but the approach you used spreads the current out over the entire radiator ... and that is a plus.  A proper capacitor is possibly more expensive than the coil, though ...

Dave   AB7E


On 8/2/2025 9:52 AM, Steve Jones wrote:
Just an alternate approach:  I made my 160M "Tee" vertical with the tee top 
long enough to resonate at around 1600 KHz.  Then cancelled the inductive reactance with 
a series air variable in a weatherproof box at the base.
73,
Steve
N6SJ



-----Original Message-----
From: TowerTalk <towertalk-bounces@contesting.com> On Behalf Of Stan Stockton
Sent: Friday, August 1, 2025 4:54 PM
To: David Gilbert <ab7echo@gmail.com>
Cc: TowerTalk@contesting.com
Subject: Re: [TowerTalk] Loading Coils

Those look very nice.

I’ve made a few coils for 40m elements and 160m loading coils using dead soft 1/4” aluminum tubing 
and a Crisco can used for a form.  The spacers were made from strips of Delrin about 3/4” wide and maybe 
1/4”-3/8” thick.  Drill holes in the Delrin with whatever spacing you want, slice it through the 
middle of the holes from one end to the other with a band saw and hold it together with zip ties once all the 
turns are encapsulated.  Three or four of these spacers have worked well for a good sized coil.

73…Stan, K5GO


Sent from my iPhone

On Aug 1, 2025, at 4:55 PM, David Gilbert <ab7echo@gmail.com> wrote:


If you have access to a 3D printer this might be an inexpensive alternative:

https://youtu.be/qAgF9Mzr8XM

or

https://youtu.be/S6spyk1GRoo

Personally, I'd go with the version that has a slight taper.  In most cases it 
would make no difference at all, and it's quite a bit simpler.

OpenSCAD is free and extremely easy to use, and the parametric design allows 
you to make a coil exactly how you want it.  If anyone needs it, I can make a 
video that walks you through the entire process.

Dave   AB7E



On 8/1/2025 1:40 PM, john@kk9a.com wrote:
That is good information.  Without the right equipment they would be
a challenge to homebrew.  Thanks for sharing!

John KK9A


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