Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mp04.r1000.mx.aol.com (Internet Inbound) with ESMTP id C8A3E38000085; Fri, 6 Jul 2012 10:17:32 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Sn9Kc-000654-PQ for rs_out_1@blacksheep.org; Fri, 06 Jul 2012 15:16:26 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Sn9Kc-00064v-CJ for rsgb_lf_group@blacksheep.org; Fri, 06 Jul 2012 15:16:26 +0100 Received: from relay2.uni-heidelberg.de ([129.206.210.211]) by relay1.thorcom.net with esmtps (TLSv1:AES256-SHA:256) (Exim 4.77) (envelope-from ) id 1Sn9Ka-0003sE-HU for rsgb_lf_group@blacksheep.org; Fri, 06 Jul 2012 15:16:25 +0100 Received: from freitag.iup.uni-heidelberg.de (freitag.iup.uni-heidelberg.de [129.206.29.204]) by relay2.uni-heidelberg.de (8.13.8/8.13.8) with ESMTP id q66EGMo4028735 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Fri, 6 Jul 2012 16:16:22 +0200 Received: from [129.206.22.206] (pc206.iup.uni-heidelberg.de [129.206.22.206]) by freitag.iup.uni-heidelberg.de (8.12.11.20060308/8.11.2) with ESMTP id q66EGKNc023932 for ; Fri, 6 Jul 2012 16:16:20 +0200 Message-ID: <4FF6F2BC.5090805@iup.uni-heidelberg.de> Date: Fri, 06 Jul 2012 16:14:20 +0200 From: =?ISO-8859-15?Q?Stefan_Sch=E4fer?= User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 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> <4FF69444.7040603@telia.com> In-Reply-To: <4FF69444.7040603@telia.com> X-Spam-Score: -2.3 (--) 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: Am 06.07.2012 09:31, schrieb Johan H. Bodin: > Stefan, > > Jim is right as always. Ferrite is unusable in VFO inductors. I just wanted to > add that Micrometals (== Amidon) Txx-6 has a slightly lower temperature > coefficient than Txx-2. [...] Content analysis details: (-2.3 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at http://www.dnswl.org/, medium trust [129.206.210.211 listed in list.dnswl.org] -0.0 T_RP_MATCHES_RCVD Envelope sender domain matches handover relay domain X-Scan-Signature: 1708620d3ce65bee0beaaede7929769a Subject: Re: LF: RE: Analog oscillators Content-Type: text/plain; charset=ISO-8859-15; 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-global-disposition: G x-aol-sid: 3039ac1dc1484ff6f37c2460 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none Am 06.07.2012 09:31, schrieb Johan H. Bodin: > Stefan, > > Jim is right as always. Ferrite is unusable in VFO inductors. I just wanted to > add that Micrometals (== Amidon) Txx-6 has a slightly lower temperature > coefficient than Txx-2. OK, convinced, thanks Johan. Probably this is why the circuit of W1VD is using a T50-6 as well ;-) > I have built successful VFOs operating directly on 7 and > 10 MHz with T50-6 cores. After some work, the drift was low enough to go > unnoticed in a QRP CW rig. That sounds promising :-) > The inductor, and many other components usually have > a positive temperature coefficient, the QRG falls as the temp' rises. Yes, CFM, that was happening here too! > One trick > is to use temperature stable capacitors for most of the tank capacitance, > "styroflex" mentioned by Peter is very good if you can find them I already use them. > , and use > negative tempco ceramic caps (N750, N1500) for a carefully selected portion of > the total capacitance. In todays world of microchips, I find it fun, educational > and rewarding to experiment with an analog VFO :-) > Others would call it "outdated", yes ;-) > 73 > Johan SM6LKM > 73, Stefan/DK7FC > > James Moritz wrote: > >> I suggest using a Txx-2 iron dust core insted of the -43 ferrite. >>