Message-ID: <31E46023A2704DF8A4431C0B44BAE495@Hugh>
From: "Hugh_m0wye" <m0wye@radiouk.com>
To: <rsgb_lf_group@blacksheep.org>
References: <001101ca621e$dcdc3380$96949a80$@princeton.edu>	<20091110192309.4v8agotbs0k0gocs@webmail6.kuleuven.be>	<004a01ca6249$d91531e0$8b3f95a0$@princeton.edu> <20091110222951.cr4qtrqagcwcowok@webmail6.kuleuven.be> <4AFAAE9C.1070304@ukonline.co.uk>
Date: Wed, 11 Nov 2009 12:55:55 -0000
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Subject: LF: Re: Ferrite characteristics
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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" <g3ldo@ukonline.co.uk>
To: <rsgb_lf_group@blacksheep.org>
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
>
>