[TowerTalk] Identifying ferrite core material

[Robert Thain]

Hello,

I've managed to lay my hands on some ferrite cores.
They were used to 'screen' multi-core
computer/communication cables.

There are no markings.
They are about an inch long, an inch in diameter and
the hole is about 1/2 an inch diameter. (27mm*25mm,
hole=12mm), but all of this doesn't help much in
identifying the material.

How can I work out what they are made of and what
their permeability is ?  

Thanks
Robert
g0hgw at yahoo.com

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