If you have an antenna analyzer like the Autek VA-1 that reads R and jX, it's
pretty straightforward.
Loop a single (insulated) wire through the center of the ferrite and connect it
to the antenna analyzer (usually easiest to do this via a UHF panel connector).
Adjust frequency until R=X.
Mix 33~10MHz
Mix 43~20-25MHz
Mix 61~50-70MHz
or so. More exact info can be had by inspecting charts of R and X vs.
frequency from any ferrite manufacturer, since those quantities are typically
measured for one turn (one wire pass through the center). Fair-rite Corp. has
very extensive technical information with their online catalog.
Of course, any other vector impedance device will work fine as well.
>
> From: Robert Thain <g0hgw@yahoo.com>
To: <towertalk@contesting.com>
> Date: 2003/03/14 Fri AM 09:44:08 EST
> To: towertalk@contesting.com
> Subject: [TowerTalk] Identifying ferrite core material
>
> 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@yahoo.com
>
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Scott Townley NX7U
Gilbert, AZ DM43di
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