Return-Path: Received: from rly-df09.mx.aol.com (rly-df09.mail.aol.com [172.19.156.22]) by air-df02.mail.aol.com (v125.7) with ESMTP id MAILINDF022-57a4afab4b4231; Wed, 11 Nov 2009 07:57:32 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-df09.mx.aol.com (v125.7) with ESMTP id MAILRELAYINDF097-57a4afab4b4231; Wed, 11 Nov 2009 07:57:27 -0500 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1N8Ck6-0002Dd-SI for rs_out_1@blacksheep.org; Wed, 11 Nov 2009 12:56:10 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1N8Ck6-0002DU-D1 for rsgb_lf_group@blacksheep.org; Wed, 11 Nov 2009 12:56:10 +0000 Received: from relay.ptn-ipout02.plus.net ([212.159.7.36]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1N8CjM-0005Jm-NT for rsgb_lf_group@blacksheep.org; Wed, 11 Nov 2009 12:55:26 +0000 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: Aq8LAKZD+kpUXebz/2dsb2JhbACBSYMqhW6GarlGkQuBMII4VAQ Received: from relay02.plus.net ([84.93.230.243]) by relay.ptn-ipout02.plus.net with ESMTP; 11 Nov 2009 12:56:01 +0000 Received: from [212.159.90.113] (helo=Hugh) by relay02.plus.net with smtp (Exim) id 1N8Cjw-0003GZ-Pe for rsgb_lf_group@blacksheep.org; Wed, 11 Nov 2009 12:56:00 +0000 Message-ID: <31E46023A2704DF8A4431C0B44BAE495@Hugh> From: "Hugh_m0wye" To: 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 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5843 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 X-Plusnet-Relay: 2e73d02b17398fa8b75164463e9e4874 X-Karma: unknown: X-Spam-Score: 3.4 (+++) X-Spam-Report: autolearn=disabled,FORGED_MUA_OUTLOOK=3.36 Subject: LF: Re: Ferrite characteristics Content-Type: text/plain; format=flowed; charset="utf-8"; reply-type=response Content-Transfer-Encoding: 7bit X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.6 required=5.0 tests=FORGED_MUA_OUTLOOK autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-AOL-IP: 193.82.116.20 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" To: 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 > >