6.5 microhenry loading coil

This model was constructed for use with a 220" telescopic antenna whip. 

The whip can be adjusted for operation on 20m by shortening one or more sections.   A coil-shortened vertical antenna calculator indicated that configuration can be moved to the 40m band by addition of a 6.5 microhenry loading coil at the base. This model was designed based on that specification.  The reading from a cheap LCR meter was consistant with the design intent.

I used 16awg tinned copper buss wire.   I added M10 heat inserts on each end.  M4 heat inserts were installed for the coil terminations.   I suggest you install the M4 screws prior to starting the coil wrap.   M10 (3/8") ring terminals were crimped to each wire end.  Wrap tightly and maintain tension until the end of the wrap is secured.   An M10 allen (aka grub) screw was installed at one end using a dab of CA glue as thread lock for attachment to the antenna base.  The whip M10 base screws into the other end.

Fusion 360 source & step files were included in addition to the .STL file.