Return-Path: Received: from mtain-mg10.r1000.mx.aol.com (mtain-mg10.r1000.mx.aol.com [172.29.96.210]) by air-ma01.mail.aol.com (v127_r1.1) with ESMTP id MAILINMA014-b4f24ba35f3a2f3; Fri, 19 Mar 2010 07:25:46 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-mg10.r1000.mx.aol.com (Internet Inbound) with ESMTP id F145F3800009A; Fri, 19 Mar 2010 07:25:44 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NsaJq-0005Yo-DR for rs_out_1@blacksheep.org; Fri, 19 Mar 2010 11:24:46 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NsaJq-0005Yf-1h for rsgb_lf_group@blacksheep.org; Fri, 19 Mar 2010 11:24:46 +0000 Received: from 113-mo2-8.acn.waw.pl ([62.121.95.113] helo=paranoid.lipkowski.org) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1NsaJo-0003WX-BO for rsgb_lf_group@blacksheep.org; Fri, 19 Mar 2010 11:24:46 +0000 Received: from paranoid.lipkowski.org (localhost [127.0.0.1]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id o2JBCoFL027769 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Fri, 19 Mar 2010 12:12:50 +0100 Received: from localhost (sq5bpf@localhost) by paranoid.lipkowski.org (8.13.7/8.13.6/Submit) with ESMTP id o2JBCo9R027766 for ; Fri, 19 Mar 2010 12:12:50 +0100 X-Authentication-Warning: paranoid.lipkowski.org: sq5bpf owned process doing -bs Date: Fri, 19 Mar 2010 12:12:50 +0100 (CET) From: Jacek Lipkowski To: rsgb_lf_group@blacksheep.org In-Reply-To: <4BA3187E.9010801@abelian.org> Message-ID: References: <4BA0A501.5050506@abelian.org> <38A51B74B884D74083D7950AD0DD85E82A1B66@File-Server-HST.hst.e-technik.tu-darmstadt.de> <4BA3187E.9010801@abelian.org> MIME-Version: 1.0 X-Spam-Score-sq5bpf: -2.601 () BAYES_00,SPF_HELO_PASS,SPF_PASS X-Scanned-By: MIMEDefang 2.56 on 10.1.3.10 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: Re: VLF: TA, 300m and new PA? Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed 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: 3039ac1d60d24ba35f383f76 X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) On Fri, 19 Mar 2010, Paul Nicholson wrote: > For me, the power levels for this long DX are getting worryingly > high as they will at some point start to cause interference to > research activity. [...] a few years ago i asked people doing geophysical research if they would be able to receive amateur transmissions at 8.9kHz. they said that the usual research is upto a few kilohertz, and that 8.9kHz is just a little over the range that they usually use for research (i think that they recorded upto 7-8kHz). if the transmitter isn't soft-keyed, then key clicks might be a problem (but would be filtered by the high Q antenna matching network) i don't know about lightning detection networks, they might be vulnerable, but Stefan's ERP is a bit small compared to a lightning bolt :) also the geophysical/atmospheric research people have a lot of experience in avoiding 50/60/16.6Hz harmonics, powerline communications (the HV type uses kHz frequencies, lots of power and _large_ antennas). so it might be not so much of a big problem after all. VY 73 Jacek / SQ5BPF