HF Loading Coil Sleeve

thingiverse

***This is a work in progress*** This is the second version of an HF loading coil I built. This version is designed to sleeve over a 1.5" piece of PVC pipe for the greatest support. My first design was entirely 3D printed, and obviously, the layers were going to be a failure point. The coil is wrapped with 18 gauge galvanized steel wire from Lowes. I attached the steel wire to the 3/8" hardware using crimp ring terminals, as you cannot solder to steel. I decided to include an SO-239 on mine as I sometimes operate POTA from the car and sometimes will use the antenna on a tripod in the grass. Tests with a 102" whip on my truck proved to be successful, according to my NanoVNA anyways. Bandwidth was a little on the narrow side, but nothing that I can't deal with. I was in a parking garage on the top floor, so I still need to test this near the ground and with a radial system. I was able to tune every band from 40m on up. I still had some coil left when I was tuning the 40m band, so you might be able to squeeze 60m in there as well. Once I optimize this design, I will begin working on a design to accommodate 60m and 75/80m too. If you have any suggestions, thoughts, or feelings, drop me a comment below!