Portable vertical antenna loading coil 123 uH

A large loading coil for a portable vertical antenna with a 123 uH potential inductance. The coil is about a foot long and 3 inches in diameter (305mm x 75mm). A clamp-on tripod is included.

The model is designed for use with 16 awg solid wire.  I used tinned copper buss wire. 62+ feet of wire is required.  M3 screws are used for assembly and M5 pan head screws were used for coil wire termination.  I suggest using crimped ring terminals for connections.  The top hole is threaded for  3/8-24.  I suggest using a thread extension for reliable repeated installion/removal of an upper whip.  A female UHF connector (SO239) is used at the bottom.  A Keystone 209 battery terminal was used on the contact ring (alternatively drill a hole & use screw+nut).

The loading coil form needs a printer capable of a 305mm vertical build to print in one piece.  An alternative, two part, version can be printed on smaller printers (see parts with “split” in the name).  The tripod legs need a 275mm build space to print in one piece.  An alternative, two part, version can be printed on smaller printers (see parts with “split” in the name).   Both two part versions have dowels that can be printed to align the parts for gluing & provide reinforcement.   When printing the two part coil, orient the models so the divided groove portion is uppermost.

I printed in ASA, using a 0.6mm nozzle & 0.3mm layer height, but other nozzle/layer combinations can be used.

Fusion 360 source and STEP files are included.