The inductance of a wound component can be greatly increased if the coil has a core of magnetic material, not only that, such a core can reduce power sapping eddy currents too, trouble is, magnetic formers such as soft iron are heavy, magnetic - which brings it's own problems and generally a pain in use!    Wouldn't it be great if a non magnetic, light and durable coil former material could be found - WELL, Mullard boffins did just that and christened their prodigal progeny, Ferroxcube!

The chemistry of the Ferroxcube material is interesting in that it comprises of mixed ferrites with manganese, nickel and zinc salts which are ground in a ball mill and then sintered which is a fusing process similar to pottery firing.

Ferroxcube cores have a high specific resistance which imbues the former with negligable eddy currents even at high frequencies.

Ferroxcube cores are unaffected by humidity.

Ferroxcube formers can be smaller and therefore much lighter than a metallic-magnetic material.

Ferroxcubes were successfully used throughout television and radio manufacture as IF coils, blocking oscillators, timebase transformers, deflection coils, control inductors, transformers - and of course ferrite aerials!!!

Sintering allows complex shapes to be homogenously manufactured provided you have a tool, just look at the complexity of this Ferroxcube deflection coil: -