Editing Magnetic core (section)

==== MPP (molypermalloy) ====
An alloy of about 2% [[molybdenum]], 81% [[nickel]], and 17% iron. Very low core loss, low hysteresis and therefore low signal distortion. Very good temperature stability. High cost. Maximum saturation flux of about 0.8 tesla. Used in high-Q filters, resonant circuits, loading coils, transformers, chokes, etc.<ref name="coilws">{{cite web|url=http://www.coilws.com/index.php?main_page=page&id=41|title=How to choose Iron Powder, Sendust, Koolmu, High Flux and MPP Cores as output inductor and chokes : CWS Coil Winding Specialist, manufacturer of transformers, inductors, coils and chokes|first=The Zen Cart™ Team and|last=others|website=www.coilws.com}}</ref>

The material was first introduced in 1940, used in [[loading coil]]s to compensate capacitance in long telephone lines. It is usable up to about 200&nbsp;kHz to 1&nbsp;MHz, depending on vendor.<ref name="chalmers"/> It is still used in above-ground telephone lines, due to its temperature stability. Underground lines, where temperature is more stable, tend to use ferrite cores due to their lower cost.<ref name="handbkferr">{{cite book|url=https://books.google.com/books?id=StbgBwAAQBAJ&dq=powder+core+%22carbonyl+iron%22&pg=PA185|title=Handbook of Modern Ferromagnetic Materials|first=Alex|last=Goldman|date=6 December 2012|publisher=Springer Science & Business Media|via=Google Books|isbn=9781461549178}}</ref>