Return-Path: Received: from mtain-di02.r1000.mx.aol.com (mtain-di02.r1000.mx.aol.com [172.29.64.6]) by air-da08.mail.aol.com (v129.4) with ESMTP id MAILINDA082-86184d868e1d19d; Sun, 20 Mar 2011 19:30:37 -0400 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-di02.r1000.mx.aol.com (Internet Inbound) with ESMTP id AC70B38000090; Sun, 20 Mar 2011 19:30:36 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Q1S3s-0000BB-1l for rs_out_1@blacksheep.org; Sun, 20 Mar 2011 23:29:28 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Q1S3r-0000B2-97 for rsgb_lf_group@blacksheep.org; Sun, 20 Mar 2011 23:29:27 +0000 Received: from relay.uni-heidelberg.de ([129.206.100.212]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Q1S3q-0007wV-DI for rsgb_lf_group@blacksheep.org; Sun, 20 Mar 2011 23:29:27 +0000 Received: from ix.urz.uni-heidelberg.de (cyrus-portal.urz.uni-heidelberg.de [129.206.100.176]) by relay.uni-heidelberg.de (8.14.1/8.14.1) with ESMTP id p2KNTO6b001752 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Mon, 21 Mar 2011 00:29:25 +0100 Received: from extmail.urz.uni-heidelberg.de (extmail.urz.uni-heidelberg.de [129.206.100.140]) by ix.urz.uni-heidelberg.de (8.13.8/8.13.8) with ESMTP id p2KNTOW0030042 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Mon, 21 Mar 2011 00:29:24 +0100 Received: from [147.142.13.67] (vpn513-067.rzuser.uni-heidelberg.de [147.142.13.67]) by extmail.urz.uni-heidelberg.de (8.13.4/8.13.1) with ESMTP id p2KNTNPK003511 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Mon, 21 Mar 2011 00:29:24 +0100 Message-ID: <4D868DD3.2030807@iup.uni-heidelberg.de> Date: Mon, 21 Mar 2011 00:29:23 +0100 From: =?ISO-8859-15?Q?Stefan_Sch=E4fer?= User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.11) Gecko/20100711 Thunderbird/3.0.6 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,RATWARE_GECKO_BUILD=1.426 Subject: LF: DK7FC LF Grabber... 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: 3039ac1d40064d868e1c0835 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) LF, It seems i have destroyed the first stage of my LF RX converter, used in my LF Grabber. I remember the discussion about the need for protecting the first stage (by 2 antiparallel diodes) of an active E field probe antenna. There were some statements that the first stage will not be destroyed but here is an example that this can actually happen. The converter still works but has lost efficiency by about 20 dB and suddenly JXN (VLF, 16.4 kHz) is visible on 136.6 kHz in my wideband window(lower window at http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_LF_DX_Grabber.html ). It seems to be a mixture with DLF (153 kHz -16.4 kHz), tnx DF6NM for the hint. The active antenna is in 2m distance to my TX antenna that is at about 10 kV during transmitting. I will repair the probe, will add some protecting diodes, change the distance of the RX by 20m. Additionally i'll compare the performance of the TX antenna as a RX antenna... 73, Stefan/DK7FC