Based on the excellent work being done in Australia with the boards using the SiliconRadar 122GHz chips, I decided to have a go at making a version of their diplexer with a thread and locknut instead of a sliding piston and grubscrew. Also I am using brass. No particular reason other than the fun of making things. I did some initial sketches in Fusion360, and made a few of the locknuts last night, now making some horns to see how they look in real life.
See here http://www.g4dbn.uk/?p=1312 for the first machining attempt.