Editing Loading coil (section)

===Mu-metal cable===
[[File:Mu-metal_cable.svg|thumb|left|300px|Mu-metal cable construction]]
[[Mu-metal]] has similar magnetic properties to permalloy but the addition of copper to the alloy increases the ductility and allows the metal to be drawn into wire. Mu-metal cable is easier to construct than permalloy cable, the mu-metal being wound around the core copper conductor in much the same way as the iron wire in Krarup cable. A further advantage with mu-metal cable is that the construction lends itself to a variable loading profile whereby the loading is tapered towards the ends.

Mu-metal was invented in 1923 by the [[Telegraph Construction and Maintenance Company]], London,<ref>Smith, WS, Garnett, HJ, ''New and improved magnetic alloys, and their application in the manufacture of telegraphic and telephonic cables'', Patent GB224972, filed 25 Aug 1923, issued 25 November 1925. patented in the US as US1582353 and US1552769</ref> who made the cable, initially, for the [[Western Union|Western Union Telegraph Co]]. Western Union were in competition with AT&T and the [[Western Electric Company]] who were using permalloy. The patent for permalloy was held by Western Electric which prevented Western Union from using it.<ref name="Green">Green</ref>
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