Design Solutions for Problems in Filters and Structures Using Self-Locking Tuning Screws

Self-locking tuning screws (SLTS), first introduced by Johanson Manufacturing therefore nicknamed “Johanson Tuning Screw”, provide an easy and fast tuning experience, relative to cumbersome tuning using tuning-bolts and locking nuts. Nevertheless, the internal spring tension embedded in SLTS is due to deep cuts in its body, which weakens the SLTS structure and make it susceptible to fracture. Proper mechanical definitions for thread oversizing and plating thickness should be defined in order to avoid such problems. This paper describes investigation of such problems and detailed design rules which arose from it.