Return-Path: Received: (qmail 90608 invoked from network); 11 Jan 2004 09:09:32 -0000 Received: from unknown (HELO ptb-mxscan01.plus.net) (212.159.14.235) by ptb-mailstore02.plus.net with SMTP; 11 Jan 2004 09:09:32 -0000 Received: (qmail 67599 invoked from network); 11 Jan 2004 09:09:32 -0000 X-Filtered-by: Plusnet (hmail v1.01) X-Priority: 3 X-MSMail-Priority: Normal X-Spam-detection-level: 11 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from ptb-mxcore01.plus.net (212.159.14.215) by ptb-mxscan01.plus.net with SMTP; 11 Jan 2004 09:09:31 -0000 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore01.plus.net with esmtp (Exim) id 1Afbb9-000HTJ-6n for dave@picks.force9.co.uk; Sun, 11 Jan 2004 09:09:31 +0000 X-Fake-Domain: majordom Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1AfbZn-0001hi-BW for rs_out@blacksheep.org; Sun, 11 Jan 2004 09:08:07 +0000 Received: from [64.12.136.161] (helo=imo-m06.mx.aol.com) by post.thorcom.com with esmtp (Exim 4.14) id 1AfbZm-0001hO-Mk for rsgb_lf_group@blacksheep.org; Sun, 11 Jan 2004 09:08:06 +0000 X-Fake-Domain: G0MRF@aol.com Received: from G0MRF@aol.com by imo-m06.mx.aol.com (mail_out_v36_r4.8.) id l.1d7.17e682e8 (4004) for ; Sun, 11 Jan 2004 04:07:31 -0500 (EST) From: G0MRF@aol.com Message-ID: <1d7.17e682e8.2d326c53@aol.com> Date: Sun, 11 Jan 2004 04:07:31 EST To: rsgb_lf_group@blacksheep.org MIME-Version: 1.0 X-Mailer: 8.0 for Windows sub 670 Subject: LF: 3C90 Al value? Content-Type: text/html; charset=windows-1252 X-Spam-Checker-Version: SpamAssassin 2.60 (1.212-2003-09-23-exp) on post.thorcom.com X-Spam-Status: No, hits=0.7 required=5.0 tests=HTML_MESSAGE,HTML_TAG_BALANCE_HTML,NO_REAL_NAME autolearn=no version=2.60 X-SA-Exim-Scanned: Yes Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-PN-SPAMFiltered: yes X-Spam-Rating: 1 Content-transfer-encoding: 8bit Hello Group.

After a 4 month wait I've received a batch of 58mm cores claiming to be 3C90, but according to the catalogue they have the wrong colour code. These are white (pos 3C11) not blue/white for 3C90.

The way to confirm is to calculate the Al value and compare to the data on 3C90 3C85 3C11 etc materials. Unfortunately 3C90 is not listed in my old data book.

I've measured the inductance of a 21 turn winding at 1.43mH.
Using  L = Al x N squared, this suggests an Al value of 3249.

Is this a good figure for 3C90?  It does seem far too low for 3C11 (5000+)
Perhaps they've changed the colour code again?

73

David    G0MRF