This general type of ferrite can also be manufactured in several vastly different grades by altering its composition and processing. Initial relative permeability (at 25C) can range from about 15 to about 1200. Saturation ranges from 2 to 3.5 kilogauss. The curie temperature ranges from 125C to 500C. Material grades have been developed for particular groups of applications. High frequency E.M.I. suppression is one example. Generally speaking, nickel zinc ferrites grades have significantly lower permeability than the manganese zinc grades. Nickel Zinc ferrites are typically used at frequencies above one megahertz. Manganese zinc ferrites are more economical below one megahertz. The upper frequency limit for nickel zinc ferrites ranges from 30 to 1000 megahertz depending on the grade. Nickel zinc ferrites vary in porosity.

Core Types Used by Butler Winding