Diamagnetism has been used for years as a method to achieve very fine
adjustments in the inductance of coils.  In RF work, a coil is wound with a
diameter of perhaps 1/4" and a length of maybe 1".  Instead of using the
typical ferrite core, a brass (diamagnetic) core is used.  When adjusted in
and out of the coil, the brass affects the inductance of the coil, but only
very slightly and in the opposite sense than that of ferrite.  Inserting
the core reduces the inductance.

Charts can be found of the permeability of diamagnetic materials, which is
less than one.  Can't remember where I've seen them, and I don't remember
frogs being listed.


Karl Cunningham
La Mesa, CA.
PSN Station #40
karlc@.......

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