Return-Path: Received: (qmail 19967 invoked from network); 11 Jan 2000 13:42:23 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by bells.core.plus.net.uk with SMTP; 11 Jan 2000 13:42:23 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.02 #1) id 1281FE-0003TF-00 for rsgb_lf_group-outgoing@blacksheep.org; Tue, 11 Jan 2000 13:21:56 +0000 Received: from helios.herts.ac.uk ([147.197.200.2]) by post.thorcom.com with esmtp (Exim 3.02 #1) id 1281FC-0003TA-00 for rsgb_lf_group@blacksheep.org; Tue, 11 Jan 2000 13:21:55 +0000 Received: from [147.197.200.44] (helo=gemini) by helios.herts.ac.uk with esmtp (Exim 3.11 #1) id 1281CR-00061U-00 for rsgb_lf_group@blacksheep.org; Tue, 11 Jan 2000 13:19:03 +0000 X-Priority: 3 X-MSMail-Priority: Normal Message-ID: <24521.200001111325@gemini> From: "James Moritz" X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Organization: University of Hertfordshire To: rsgb_lf_group@blacksheep.org Date: Tue, 11 Jan 2000 13:25:11 +0000 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 8bit Subject: LF: 73kHz / Receiving Loops X-Mailer: Pegasus Mail for Win32 (v3.11) Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: Dear LF Group, Thank you to everyone who listened out for my signal on 73kHz last night - I was very pleased to be able to work Mike, G3XDV with 559 reports both ways. Other reports have been negative so far; I'm afraid the signal Toni HB9ASB detected wasn't me - my frequency was close to 72.00kHz. I hope to try again shortly; I should be able to get my antenna a bit higher before then. Regarding loops for LF reception, I was involved in some research work at University of Herts some while ago to develop loop antennas for LF EMC measurement purposes. We also tried using ribbon cable, and found the losses and stray capacitance to be very high - we put this down to the PVC insulation, and the extremely thin conductors of this type of cable. Almost any other type of wire is better; we had good results using the inner conductor and insulation of TV type semi-airspaced coax cable; the cellular polythene insulation keeps stray C down and has low losses, even with the wires tightly bundled together. You need quite a bit of coax, though! Air-spaced windings are probably the best possible, but are less convenient mechanically. Cheers, Jim Moritz 73 de M0BMU