Re: Coil forms, Q, and instruments

Jim Sheldon

I will Joe.  I have a couple more things before I post the complete package.  I still need to design a center insulator to take a BNC connector and one to take an SO-239 before I post the files.

I’ll work on those tomorrow after breakfast and hopefully have a zipfile with all the .stl and I’ll include the .f3d files for those who can use them.


On Jul 23, 2021, at 8:53 PM, cornhusker via <cornhusker@...> wrote:

I hope you can post the STL files!   This looks great!
73 de K0NEB 

On Fri, Jul 23, 2021 at 8:01 PM, Jim Sheldon
<w0eb@...> wrote:
Jim G's work inspired me to work on a 40/20 meter trap doublet/dipole/inverted vee with 3D printed trap coil forms and insulators.  I have the traps coil forms done and the end/trap center insulators done and I really got lucky.  A 20 meter trap should have 4.7 uH worth of inductance with a 27pF capacitor to resonate at 14.100 MHz and TOTALLY by accident, my initial print of the coil form wound with 16 turns of #20 wire just so happened to come out to just a bit over 4.7uH when I measured it.

I worked on the design (I used AudoDesk's (free for personal/non-commercial use) Fusion 360 as my CAD program.  F360 gives a bit more finesse when making threaded cylinders than TinkerCad does. 

Taking Jim's advice, I also added blockers to the inside of the coil form so the insulator will slide tightly inside and allow you to wind the coil first and pick which 90 degree point gives you the best coil positioning.

Here's a couple of pictures of the lot.

Jim Sheldon, W0EB  -- 3D printing is a super 2nd hobby to HamRadio --





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