Hi Peter,
I tend to do something similar to Hugh but perhaps a little less
"scientifically" viz.; When playing toroids etc. I determine which ones
are successful for a particular application and use an LCR meter to
measure the inductance of 5 turns of approx 14g copper and mark the
toroid accordingly. My little stock is marked in this way and a note is
made of the apps for which they were suitable (or in some cases
unsuitable). I am sure there are much better ways but it gets me by.
73 de Pat g4gvw
On Wed, 2009-11-11 at 12:55 +0000, Hugh_m0wye wrote:
> 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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