The application for this stepping motor is a ham radio HF magnetic loop antenna. A large variable capacitor tunes the magnetic loop. This kind of antenna is very selective and has a very small bandwidth where a SWR (standing wave ratio) approaches 1:1. You almost cannot tune it by hand and expect to hit the lowest SWR.
Plus, the antenna may be mounted away from the operator (me). So you really need a small, very slow motor that can change direction.
