Return-Path: Received: (qmail 21983 invoked from network); 11 Jan 2004 12:09:46 -0000 Received: from unknown (HELO ptb-mxscan01.plus.net) (212.159.14.235) by ptb-mailstore01.plus.net with SMTP; 11 Jan 2004 12:09:46 -0000 Received: (qmail 91460 invoked from network); 11 Jan 2004 12:09:46 -0000 X-Filtered-by: Plusnet (hmail v1.01) X-Spam-detection-level: 11 Received: from ptb-mxcore01.plus.net (212.159.14.215) by ptb-mxscan01.plus.net with SMTP; 11 Jan 2004 12:09:45 -0000 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore01.plus.net with esmtp (Exim) id 1AfePZ-000NgN-DS for dave@picks.force9.co.uk; Sun, 11 Jan 2004 12:09:45 +0000 X-Fake-Domain: majordom Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1AfePL-0004gT-G4 for rs_out@blacksheep.org; Sun, 11 Jan 2004 12:09:31 +0000 X-No-DNS-For: 212.1.130.141 Received: from [212.1.130.141] (helo=smtp-1.visp.telinco.net) by post.thorcom.com with esmtp (Exim 4.14) id 1AfePK-0004gJ-Q3 for rsgb_lf_group@blacksheep.org; Sun, 11 Jan 2004 12:09:30 +0000 Received: from [80.40.55.64] (helo=RSGB613192) by smtp-1.visp.telinco.net with smtp (Exim 3.36 #1) id 1AfePJ-00007f-00 for rsgb_lf_group@blacksheep.org; Sun, 11 Jan 2004 12:09:29 +0000 X-Bad-Message-ID: no DNS (RSGB613192) Message-ID: <000b01c3d83b$c8bff800$045bfea9@RSGB613192> From: "Andy talbot" To: rsgb_lf_group@blacksheep.org References: <1d7.17e682e8.2d326c53@aol.com> Date: Sun, 11 Jan 2004 12:09:35 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.00.2615.200 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Subject: LF: Re: 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=0.8 required=5.0 tests=HTML_30_40,HTML_MESSAGE 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: 2 Content-transfer-encoding: 8bit

I thought Al values was a meaningless term for pure ferrite materials and is only published as a guideline as it changes dramatically with temperature and B - for a true/ideal transformer it would ideally be infinite. Things like bulk resistivity and the area inside the hysteresis curve are more significant as they decide the frequency and power handling of any material.

Andy G4JNT

----- Original Message -----

From: G0MRF@aol.com

To: rsgb_lf_group@blacksheep.org

Sent: Sunday, January 11, 2004 9:07 AM

Subject: LF: 3C90 Al value?

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