Unun or Balun Box and Lid with Optional Seal

thingiverse

This is an unun/balun box used for amateur radio or shortwave listening. There's a lid and seal too, but you may not need the seal unless you plan to print it in something like NinjaFlex to use the box outside. It's designed to house a FT240-43 toroid and SO-239 mount with M4 ground and antenna bolt holes. The configuration I built (see photo of completed build) is a 1:49 unun to match the impedance of an EFHW antenna with 50 ohm coax. However, it's designed with OpenSCAD so is fully parametric and if you use OpenSCAD it can be configured to house any type of unun/balun. Tweaking the parameters near the top of the OpenSCAD file will change practically any of the dimensions and the box design will re-generate to accommodate the changes. Oh and if you're wondering what the flat discs are on the corners, these help prevent warping during printing. They can easily be removed after printing, or removed from the design completely in OpenSCAD.