The AM Forum

Hi everyone,

The plastic spacers in my Johnson Ranger were very brittle and cracked and fell off in a few places.  So, I designed an upper and lower spacer that can be 3D printed for the tank coil.  Since the coil spacing varies around the circumference of the coil, I created the spacers for where I needed them.  I found that PETG was a better material than PLA.  I tack glued the coil to the spacers with a little Gorilla crazy glue.  

I hope this can help someone who has the same issue and access to a 3D printer.

https://www.thingiverse.com/thing:4520795

73,
Tony W1TTL

That is real neat! The same system could be used for the B&W 850 series tank coils or for any coil for that matter. One question, some plastics are electro conductive at RF. Is that an issue with modern materiel's?

Looks like the stuff is good for making water bottles too.
Here's some data on the material but no mention of reactions in RF environment:
https://www.simplify3d.com/support/materials-guide/petg/
Of course, depending on power and frequency, RF can really heat up things adjacent to it.

Material comparisons: https://www.simplify3d.com/support/materials-guide/properties-table/?highlight=petg

I was contemplating the same thing but in terms of dielectric coefficient.

I think most of the older plastic coil spacers were made of Lexan or Bakelite.


Phil

Very nice.

PETG looks like PVC and not to different from Lexan. Ceramic is awfully nice!

At HF and since the coil is not totally surrounded by these plastics, I suspect not an issue. At 1 MHz, they both have comparable loss tangent, about 0.01.

Alan

Gentlemen,

Thank you for looking into the dielectric properties of PETG.  Glad to hear it should be good in the long run for what I'm using it for.  So far, I haven't noticed any issues with my transmissions.

73,
Tony W1TTL