Adjustable low-loss capacitor

Claim 1

In an adjustable air dielectric capacitor having a hollow cylindrical stator electrode and a coaxially positioned cylindrical rotor electrode and including threaded tuning means operatively coupled to the rotor for making precision capacity adjustments by moving the rotor axially of the stator the improvement which comprises an electrically conductive body portion mounting said stator, a cylindrical electrically insulating housing surrounding said electrodes and attached at one end to said body, a hollow cylindrical electrically conducting bushing having an outer diameter about equal to that of said housing and having one circular end coupled to said housing, the hollow center of said bushing being threaded and having a diameter about equal to that of inner walls of said housing, a generally cylindrical rotor body having a threaded outer surface .Iadd.with threads initially aligned and capable of .Iaddend.engaging the threads of said bushing, said rotor electrode being coupled at one circular end to one end of said rotor body for movement therewith, a pair of parallel flat bottomed slots of equal depth formed in the threaded portion of said rotor body extending radially inwardly from diametrically opposed threaded rotor surfaces a distance substantially greater than the radius of said rotor body, .Iadd.a first .Iaddend.one of said slots being positioned closely adjacent to the other end of said body thereby defining a relatively resilient threaded end portion on said rotor body, the second slot being formed closely adjacent to said .[.one.]. .Iadd.first .Iaddend.slot for forming a resilient connecting portion between the said .[.one end of said rotor body and said rotor body threaded end portion.]., .Iadd.slats .Iaddend.and .[.portions of the rotor body.]. .Iadd.said resilient portion being axially compressed to resiliently misalign said threads and impart a permanent deformation to said rotor body whereby said misaligned portion of the rotor body .Iaddend.threads on opposite sides of said slots .[.exerting.]. .Iadd.exert .Iaddend.an axially directed gripping force on the threads of said bushing thereby resisting unintentional turning and eliminating relative lateral movement of said electrodes.