Design Methods for Soft Magnetic Materials in Radio

The present paper is concerned with a study of design methods for soft magnetic materials such as those used in radio broadcast receivers and similar apparatus. The design of such devices as interstaged transformers calls for more than choosing points on curves in a standard handbook and computing mechanical or electrical details by ordinary power transformer theory. Radio transformer design is usually complicated by the effect of passing d-c space current through the winding or by the use of an air-gap to prevent saturation of the core by uni-directional current. The procedure to follow when one of these disturbing effects is present is not very difficult, but it becomes somewhat involved if an efficignt design is wanted when both are present. In this paper an attempt is made to present a workable method of taking account of these disturbing effects. The method intvolves the determination of the apparent and maximum obtainable permeabilities of the magnetic materials so that a proper conclusion nay be arrived at by an application of simple engineering methods.