Return-Path: Received: from rly-mf05.mail.aol.com (rly-mf05.mail.aol.com [172.20.29.175]) by air-mf09.mail.aol.com (v119.9) with ESMTP id MAILINMF093-95e46fc079b3d; Thu, 27 Sep 2007 15:42:28 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-mf05.mail.aol.com (v119.9) with ESMTP id MAILRELAYINMF054-95e46fc079b3d; Thu, 27 Sep 2007 15:42:21 -0400 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1IazEz-0003F4-71 for rs_out_1@blacksheep.org; Thu, 27 Sep 2007 20:41:41 +0100 Received: from [83.244.159.144] (helo=relay3.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1IazEx-0003Ev-SO for rsgb_lf_group@blacksheep.org; Thu, 27 Sep 2007 20:41:39 +0100 Received: from smtpout05-04.prod.mesa1.secureserver.net ([64.202.165.221] helo=smtpout05.prod.mesa1.secureserver.net) by relay3.thorcom.net with smtp (Exim 4.63) (envelope-from ) id 1IazEr-0001OR-5F for rsgb_lf_group@blacksheep.org; Thu, 27 Sep 2007 20:41:39 +0100 Received: (qmail 5534 invoked from network); 27 Sep 2007 19:41:08 -0000 Received: from unknown (208.37.242.34) by smtpout05-04.prod.mesa1.secureserver.net (64.202.165.221) with ESMTP; 27 Sep 2007 19:41:08 -0000 Message-ID: <46FC071D.2090202@w1tag.com> Date: Thu, 27 Sep 2007 15:40:13 -0400 From: John Andrews User-Agent: Thunderbird 2.0.0.6 (Windows/20070728) MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <000a01c80132$aae29df0$83e41a52@enigma> In-Reply-To: <000a01c80132$aae29df0$83e41a52@enigma> X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: Re: LF: A question of calibration Content-Type: text/plain; charset=ISO-8859-1; format=flowed 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=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 X-AOL-SCOLL-AUTHENTICATION: listenair ; SPF_helo : X-AOL-SCOLL-AUTHENTICATION: listenair ; SPF_822_from : X-Mailer: Unknown (No Version) Malcolm, > Hi. Can anyone reassure me. Be reassured. Your meter is measuring the magnetic field, and the calibration setup is primarily generating a magnetic field. The cal is being done under near-field conditions to permit the use of low power and take advantage of knowing the mag field accurately based on geometry and current measurement. The scale conversion to electric field remains valid as long as you agree to take your real measurements under far-field conditions. A further discussion of calibration techniques including a simpler arrangement than Helmholtz coils may be found at: http://www.w1tag.com/LF_FSM.htm John Andrews, W1TAG