In this article, I describe the flying saucer resonator build using a 3D printer rather than sawing PVC material manually. It’s fast and cheap.
In his detailed instructions in May 2017 QST, Barry Boothe provides a complete list of materials and construction process. (See here for an open source description if you are not an ARRL member.) I chose to 3D print the saucers using PETG plastic rather than the tedious method of cutting them out of PVC sheets. The dielectric properties of PETG are similar to PVC.
My saucers were shaped to fit easily onto a ¾ inch diameter aluminum tube, as shown above left. Alternately, Boothe used ½ inch diameter tube. In most other respects, I followed his approach closely.
These resonators are a combination of pancake wound inductor (coil) and a capacity hat at the end of the coil. I used #20 AWG Teflon coated wire rather than #22 because I had lots of the slightly larger wire on hand. I think some adjustment will be needed, so I made the coils a few turns longer to start.
For the capacity hat, I used 304 stainless spring steel wire, which I found on eBay for around $6 per five meter length. You need ten meters to make 30 and 80 meter hats. I formed the loops and attached them with 6-32 screws to the saucer, as shown above right. All in all, the spring wire was the largest cost component, with each saucer coming in under $10 in plastic, wire and hardware.
If you are interested in printing these yourself, I will provide the STL files for 5 and 6 inch diameter forms on request.
Flying Saucer Resonator Build – Connections to Antenna
As shown below, I used readily available ¼ inch bolts and nuts to make a mechanical connection with the aluminum tube.
As you can see, a captive nut is used to tighten the bolt against the antenna pipe. A second nut is used to tighten the coil terminal against the mounting bolt. This approach provides a good mechanical and electric connection for the flying saucer resonator build.
I just love being able to apply my 3D printing skills to projects like this. In addition, I 3D printed clamps for mounting the antenna and connecting the coax. My biggest challenge is converting between Metric and Imperial measurements!