Return-Path: Received: from rly-df04.mx.aol.com (rly-df04.mail.aol.com [172.19.156.17]) by air-df07.mail.aol.com (v125.7) with ESMTP id MAILINDF073-5434afaff01b3; Wed, 11 Nov 2009 13:14:43 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-df04.mx.aol.com (v125.7) with ESMTP id MAILRELAYINDF042-5434afaff01b3; Wed, 11 Nov 2009 13:14:27 -0500 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1N8HhB-0003lT-AS for rs_out_1@blacksheep.org; Wed, 11 Nov 2009 18:13:29 +0000 Received: from [83.244.159.144] (helo=relay3.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1N8HhA-0003lK-Sg for rsgb_lf_group@blacksheep.org; Wed, 11 Nov 2009 18:13:28 +0000 Received: from mailout01.t-online.de ([194.25.134.80]) by relay3.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1N8Hh8-0005C7-2V for rsgb_lf_group@blacksheep.org; Wed, 11 Nov 2009 18:13:28 +0000 Received: from fwd05.aul.t-online.de by mailout01.t-online.de with smtp id 1N8GQo-0006Ui-02; Wed, 11 Nov 2009 17:52:30 +0100 Received: from [192.168.2.22] (XNg33aZT8hmelHJUXQlONqXVhnZ6tTK4PH4xQEdrj4yZbhX+6GEwCRheuyw69PVwm6@[93.196.56.230]) by fwd05.t-online.de with esmtp id 1N8EkP-1rIiRc0; Wed, 11 Nov 2009 16:04:37 +0100 MIME-Version: 1.0 From: hajo.brandt.dj1zb@t-online.de 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> In-Reply-To:<4AFAAE9C.1070304@ukonline.co.uk> To: X-Mailer: T-Online eMail 6.08.0003 Date: 11 Nov 2009 15:04 GMT Message-ID: <1N8EkP-1rIiRc0@fwd05.t-online.de> X-ID: XNg33aZT8hmelHJUXQlONqXVhnZ6tTK4PH4xQEdrj4yZbhX+6GEwCRheuyw69PVwm6 X-TOI-MSGID: 3ca2b1d6-eda1-4992-ad2c-a3ce7d823fb6 X-Spam-Score: 0.6 (/) X-Spam-Report: autolearn=disabled,NO_REAL_NAME=0.55,UNPARSEABLE_RELAY=0.001 Subject: Re: LF: Ferrite characteristics Content-Type: Text/Plain; Charset="ISO-8859-1" Content-Transfer-Encoding: 8Bit X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.3 required=5.0 tests=NO_REAL_NAME 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 Dear Peter, besides measuring the AL value as alrady described there is another rather simple way to determine the characteristics of ferrites: Take an Ohms meter and see if the core itself is conducting or not, when the contacts touching the core are separated about half an inch or so. Very high resistance is typical for nickel-zinc cores (suitable for rf transformers) whilst conducting cores are of the magnesium-zinc type, to be used at much lower frequencies. Good luck! 73 Ha-Jo, DJ1ZB "Peter Dodd" schrieb: > 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 > > >