Rf choke with windings separated by a distance equal to the smaller core diameter

Abstract

A radio frequency (RF) choke having improved insertion loss and reduced modulation hum. The choke includes a core having first and second end portions which have similar magnetization and saturation characteristics, and which may be of equal or unequal diameters. A plurality of turns of a first conductor encircle the first end portion of the core in a first direction to define a first winding. Pluralities of turns of a second conductor encircle the second end portion of the core in the opposite direction to define second and third windings. The numbers and spacings of the turns of the first winding are so related to the numbers and spacings of the turns of the second and third windings that relatively low frequency currents flowing through said windings generate substantially canceling fluxes in the first and second end portions of the core, while relatively high frequency currents flowing through said windings do not generate substantially canceling fluxes in the first and second end portions of the core. The windings associated with the first and second end portions of the core, and/or the end portions of the core may be separated by predetermined respective distances, thereby improving the ability of the choke to discriminate between high and low frequency currents.