Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mk05.r1000.mx.aol.com (Internet Inbound) with ESMTP id 9A1E938000087; Fri, 10 Aug 2012 14:21:20 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1SztpA-00042j-1D for rs_out_1@blacksheep.org; Fri, 10 Aug 2012 19:20:40 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Sztp9-00042Z-Jf for rsgb_lf_group@blacksheep.org; Fri, 10 Aug 2012 19:20:39 +0100 Received: from moutng.kundenserver.de ([212.227.17.10]) by relay1.thorcom.net with esmtp (Exim 4.77) (envelope-from ) id 1Sztp4-0003S7-5N for rsgb_lf_group@blacksheep.org; Fri, 10 Aug 2012 19:20:38 +0100 Received: from [192.168.2.104] (p4FD171F9.dip.t-dialin.net [79.209.113.249]) by mrelayeu.kundenserver.de (node=mreu1) with ESMTP (Nemesis) id 0M1kaM-1TtWaB0Pco-00t8Mr; Fri, 10 Aug 2012 20:20:33 +0200 Message-ID: <502550F0.10000@legal-medicine.de> Date: Fri, 10 Aug 2012 20:20:32 +0200 From: pws User-Agent: Mozilla/5.0 (X11; Linux i686; rv:13.0) Gecko/20120601 Thunderbird/13.0 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <4FC39CF3.7020701@legal-medicine.de> <5024439B.1000201@iup.uni-heidelberg.de> In-Reply-To: <5024439B.1000201@iup.uni-heidelberg.de> X-Provags-ID: V02:K0:QpxvDDuGXXVSTOcOkryiXM3l5WcFVzQD8G4M83jtYHr WzlmaKkAqFCcXNu1RB4T6BPpfsrT7Br37vIlRxp0l1jLaZvJxO 6VqLWvLVwrM2wcMNQCrxOaC+z3EAwaQ3LpfxmBXNUaS3ehn+T2 JCnWawZE5yBw5huus8r6mugJ2MPSumttip8zL1xOZcfwkkiamI ZQXP4Hhzgzgb9eqzzppICcN38UMfXygk+4dwNRqdvkxvhvES3D 6HApPVBw/t3Uu4x7Ze33GYVkx1bY5AY6m1HREzlVJFFtnMB7by CD3l8T2hWCRuKa+uhWimsXcRNpdbcQoNdtdsod8B2d0PulmPOA Kmjy+opAo2IDUQ4xFkwL3fI2l0RSow3CX17NDWuF/ 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: Hi Stefan, You wrote: > ... > However it does not work really well in the first attempt. The probes are > just 2 short wires from the resistors. If i come closer to one of them with > my hand i am getting some V (!) output signal from my own 136 kHz > transmission which take place in the moment. > ... [...] 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 [212.227.17.10 listed in list.dnswl.org] -0.0 SPF_HELO_PASS SPF: HELO matches SPF record X-Scan-Signature: 046f068074e745d5c60ca47deee9b503 Subject: Re: LF: VLF/LF-Preamp 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-SCOLL-SCORE: 0:2:432468544:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d618950255120368e X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none Hi Stefan, You wrote: > ... > However it does not work really well in the first attempt. The probes are > just 2 short wires from the resistors. If i come closer to one of them with > my hand i am getting some V (!) output signal from my own 136 kHz > transmission which take place in the moment. > ... O.K., that's how a well balanced amplifier should behave: only the difference matters. So try using longer "legs" and check for SNR and local interferences. > ... > So far i have no TLE2426 on hand, so i used 2x 100 Ohm / 2W resistors and > 47uF in parallel to each one to form a virtual ground. The AF transformer > you mentioned does not work on 137 and 475 kHz of course. > ... No, the transformers I'm using are performing well from 2 up to >300 kHz. Available: http://www.oppermann-electronic.de/html/ubertrager.html TDK 205 U, 4:1 instead of 2.5:1 as mentioned there. Capacitive coupling <10 pF. > ... > What is your final configuration and where did you connect the shield of > the CAT5 cable? Have you found any improvements on the schematic? Or is the > project lost in the junk box? :-) > ... The configuration did not change. I made some tests last weekend out in the field. "Alpha" peaked up to 30dB SNR and I could hear insects landing on one of the legs quite well. I'm using well shielded AF-cable not CAT-X. Both shields are kept floating from "real earth". OT: more and more strong echos now at 49749 kHz from Perseides. Peter, df3lp