Wrap a few turns of wire through them and measure their inductance. That
will tell you the AL factor (inductance/square root(turns)) (and by
implication the permeability)..
Measure at a few different frequencies, and that will give you the loss
characteristics (if you can measure loss at each frequency, so much the
better, but, you can get a feel for it by seeing where the inductance
apparently starts to die off)
----- Original Message -----
From: "Robert Thain" <firstname.lastname@example.org>
Sent: Friday, March 14, 2003 6:44 AM
Subject: [TowerTalk] Identifying ferrite core material
> 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 ?
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