Hi Peter,
In the past I have wound a few turns aound the core and measured the
Inductance. From this you can calculate the AL value, or "Inductance Factor"
in nH per turns squared. I measured the Inductance on an LCR meter, but you
could resonate the coil against a capacitor and use a GDO as you suggest.
Number of turns = square root of (L / AL) where L is inductance in nH.
From this you can compare to published figures, for example the RM series of
Ferrite cores (RS used to publish tables which included the AL value, in
their catalogues)
73
Hugh M0WYE
----- Original Message -----
From: "Peter Dodd" <[email protected]>
To: <[email protected]>
Sent: Wednesday, November 11, 2009 12:31 PM
Subject: LF: Ferrite characteristics
Does anyone know of a method of measuring the characteristics
(permeability) of ferrite cores? I have a box of these most without any
identification although I do have T200, 68-2T and T68-2s whose
characteristics are known.
It occurs to me that you can make a tuned circuit and measure resonance
with a GDO when a ferrite core is inserted into the inductance. A graph
could be made of the different resonances with different cores, to
extrapolate the unknowns.
However I think that ferrite bulk might be a problem. For example I guess
the red T cores use the same material but would there be a difference
between the T200 and the T68?
I have lots of material about ferrites in general - I just want to know
what I have in my junk box. I am not interested in exact measurements, I
just want to know if a core is suitable for a specific job.
Regards
Peter, G3LDO
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