Return-Path: Received: from rly-md05.mx.aol.com (rly-md05.mail.aol.com [172.20.29.143]) by air-md06.mail.aol.com (v125.7) with ESMTP id MAILINMD061-9044afac31b273; Wed, 11 Nov 2009 08:59:05 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-md05.mx.aol.com (v125.7) with ESMTP id MAILRELAYINMD054-9044afac31b273; Wed, 11 Nov 2009 08:58:53 -0500 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1N8Dhh-0002V0-JR for rs_out_1@blacksheep.org; Wed, 11 Nov 2009 13:57:45 +0000 Received: from [83.244.159.144] (helo=relay3.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1N8Dhg-0002Ur-Sx for rsgb_lf_group@blacksheep.org; Wed, 11 Nov 2009 13:57:44 +0000 Received: from mail.ebirds.it ([151.8.133.126]) by relay3.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1N8Dhe-0002bV-6R for rsgb_lf_group@blacksheep.org; Wed, 11 Nov 2009 13:57:44 +0000 Received: by mail.ebirds.it (Postfix, from userid 65534) id CE626587AA; Wed, 11 Nov 2009 14:57:39 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by mail.ebirds.it (Postfix) with ESMTP id 3596C587A5 for ; Wed, 11 Nov 2009 14:57:38 +0100 (CET) X-Virus-Scanned: amavisd-new at ebirds.it Received: from mail.ebirds.it ([127.0.0.1]) by localhost (mamba02.ebirds.it [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id GvB7RAkJcEzJ for ; Wed, 11 Nov 2009 14:57:38 +0100 (CET) Received: from imac2 (host185-41-static.24-87-b.business.telecomitalia.it [87.24.41.185]) by mail.ebirds.it (Postfix) with ESMTP id ABE605368E; Wed, 11 Nov 2009 14:57:37 +0100 (CET) X-Mailer: QUALCOMM Windows Eudora Version 7.1.0.9 Date: Wed, 11 Nov 2009 14:57:15 +0100 To: rsgb_lf_group@blacksheep.org, rsgb_lf_group@blacksheep.org From: Marco IK1ODO -2 In-Reply-To: <4AFAAE9C.1070304@ukonline.co.uk> 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> Mime-Version: 1.0 Message-Id: <20091111135737.ABE605368E@mail.ebirds.it> X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: Re: LF: Ferrite characteristics Content-Type: text/plain; charset="us-ascii"; format=flowed X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=none 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 At 15:15 11-11-09, Peter Dodd wrote: >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 Peter, just my 2 Eurocents... wound a few (5 to 20) turns, measure L and take physical dimensions of the toroid, use G4FGQ's toroid.exe, and then play with the parameters in the program to find wich permeability gives the L you measured. The program is pretty accurate, Reg did a nice job. 73 - Marco IK1ODO