Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dd05.r1000.mx.aol.com (Internet Inbound) with ESMTP id 01E6D380000A6; Fri, 6 Jul 2012 03:40:47 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Sn38y-0004Ug-Ub for rs_out_1@blacksheep.org; Fri, 06 Jul 2012 08:40:00 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Sn38y-0004US-9I for rsgb_lf_group@blacksheep.org; Fri, 06 Jul 2012 08:40:00 +0100 Received: from smtp-vbr9.xs4all.nl ([194.109.24.29]) by relay1.thorcom.net with esmtp (Exim 4.77) (envelope-from ) id 1Sn38w-0002Ly-13 for rsgb_lf_group@blacksheep.org; Fri, 06 Jul 2012 08:39:59 +0100 Received: from pc-roelof (ndb.demon.nl [82.161.81.65]) by smtp-vbr9.xs4all.nl (8.13.8/8.13.8) with ESMTP id q667dpHU063774 for ; Fri, 6 Jul 2012 09:39:57 +0200 (CEST) (envelope-from roelof@ndb.demon.nl) To: rsgb_lf_group@blacksheep.org References: <7E7DFBB4D102A04DB5ADC88D66628A4A0FAB99CC@ICTS-S-MBX5.luna.kuleuven.be> <1SmrFA-199XcW0@fwd21.t-online.de> <4FF5EB68.9040507@iup.uni-heidelberg.de> <4FF61402.6000703@iup.uni-heidelberg.de> Date: Fri, 06 Jul 2012 09:39:44 +0200 MIME-Version: 1.0 From: "Roelof Bakker" Message-ID: In-Reply-To: <4FF61402.6000703@iup.uni-heidelberg.de> User-Agent: Opera Mail/12.00 (Win32) X-Virus-Scanned: by XS4ALL Virus Scanner X-Spam-Score: 0.0 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Hello Stefan, A FT-37-43 ferrite toroid is not suitable for a VFO as you found. Powdered iron cores from Amidon are much better in this regard. From the common available parts -6 material has the lowest temperature coefficient, -7 is slightly better: [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [194.109.24.29 listed in list.dnswl.org] X-Scan-Signature: 7aa9ad08848e488e22e0ff1d71f4ef1d Content-Type: text/plain; charset=iso-8859-15; format=flowed; delsp=yes Subject: Re: LF: RE: Analog oscillators 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-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:274940064:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d40914ff6967f6a07 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none Hello Stefan, A FT-37-43 ferrite toroid is not suitable for a VFO as you found. Powdered iron cores from Amidon are much better in this regard. From the common available parts -6 material has the lowest temperature coefficient, -7 is slightly better: T-50-2: 95 ppm/C T-50-6: 35 ppm/C T-50-7: 30 ppm/C The temperature coefficient does not vary with the size of the toroid. There are tricks to achieve mechanical stable windings on a Toroid. One is to wind it as tight as you can and than place the coil in boiling water for 10 minutes. This removes the mechanical stress and the winding settles down. 73, Roelof, pa0rdt