Greetings Frank,
A member of my radio club just bought a set of ready-made coils from Force 12
founder N6BT.
I saw a pic of the coils and they appeared very robust.
In his case, they are designed to replace the linear loading on his 2el 40m
yagis.
If you are doing a DIY, maybe contact him
(https://nextgenerationantennas.com/founder-of-force-12%2C-inc he is still
making and selling antenna stuff).
You could design your DIY 40m rotary dipole based on his coil characteristics.
He also says he is making his original antennas again, maybe you could pick up
an entire rotary dipole from him, I believe they made one back in the 90s.
Thanks for all the contest QSOs as well over the years,
73 and all the best,
Darrell AB2E
________________________________
From: TowerTalk <towertalk-bounces@contesting.com> on behalf of W7TMT - Patrick
<W7TMT@outlook.com>
Sent: Monday, March 15, 2021 8:33 PM
To: Frank VO1HP <invl160@gmail.com>; towertalk@contesting.com
<towertalk@contesting.com>
Subject: Re: [TowerTalk] 40M Loading Coils
I've no source for premade but several links that might help you roll your own.
I used AD5X's technique to make loading coils for a shortened 40/15M dipole I
use on my sailboat. The elements are supported on two Jackite telescoping
fiberglass poles joined end-to-end in the middle. While the poles would easily
support a full sized 40M antenna I don't have the room due to other vessel
masts on either side along the dock. Happy to send you a picture of a coils I
made if you want. Note that I used his method of spacing the windings but
didn't need the support structure he describes for his vertical application.
AD5X's article is here: http://www.ad5x.com/images/Articles/CoilRevB.pdf
There is another one that may be of interest here:
"Homebrew Your Own Inductors," by Robert H. Johns, W3JIP, QST, Aug 1997, p 35
I used W8WWV's method for winding a single large coil for my 80' high 160M
vertical over saltwater. I used 1/8" refrigeration tubing for that one.
His article is here:
http://www.seed-solutions.com/gregordy/Amateur%20Radio/Experimentation/HiQCoil.htm
K7MEM has some nice on-line calculators that might be helpful here:
http://www.k7mem.com/Site_Map.html#HF%20Wire
Patrick, W7TMT
-----Original Message-----
From: TowerTalk <towertalk-bounces@contesting.com> On Behalf Of Frank VO1HP
Sent: Monday, March 15, 2021 16:50
To: towertalk@contesting.com
Subject: [TowerTalk] 40M Loading Coils
Does anyone know of a source of High Q 40M load coils and one could use for a
DIY Rotary Dipole?
73
Frank VO1HP
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