Return-Path: Received: from rly-mg02.mx.aol.com (rly-mg02.mail.aol.com [172.20.83.108]) by air-mg10.mail.aol.com (v123.4) with ESMTP id MAILINMG102-9fc4a0941cc1fe; Tue, 12 May 2009 05:30:58 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-mg02.mx.aol.com (v123.4) with ESMTP id MAILRELAYINMG026-9fc4a0941cc1fe; Tue, 12 May 2009 05:30:53 -0400 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1M3oJ3-00021u-On for rs_out_1@blacksheep.org; Tue, 12 May 2009 10:29:49 +0100 Received: from [83.244.159.144] (helo=relay3.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1M3oJ3-00021l-Cg for rsgb_lf_group@blacksheep.org; Tue, 12 May 2009 10:29:49 +0100 Received: from mtaout02-winn.ispmail.ntl.com ([81.103.221.48]) by relay3.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1M3oJ2-0001j0-Li for rsgb_lf_group@blacksheep.org; Tue, 12 May 2009 10:29:49 +0100 Received: from aamtaout01-winn.ispmail.ntl.com ([81.103.221.35]) by mtaout02-winn.ispmail.ntl.com (InterMail vM.7.08.04.00 201-2186-134-20080326) with ESMTP id <20090512092931.NHOF25388.mtaout02-winn.ispmail.ntl.com@aamtaout01-winn.ispmail.ntl.com> for ; Tue, 12 May 2009 10:29:31 +0100 Received: from [192.168.2.33] (really [82.22.242.113]) by aamtaout01-winn.ispmail.ntl.com (InterMail vG.2.02.00.01 201-2161-120-102-20060912) with ESMTP id <20090512092931.TEKL13254.aamtaout01-winn.ispmail.ntl.com@[192.168.2.33]> for ; Tue, 12 May 2009 10:29:31 +0100 From: "Mike Dennison" To: rsgb_lf_group@blacksheep.org Date: Tue, 12 May 2009 10:29:28 +0100 MIME-Version: 1.0 Message-ID: <4A094F88.31094.2E46CD4@mike.dennison.ntlworld.com> In-reply-to: <003801c9cfed$3754c170$0301a8c0@mal769a60aa920> References: <4A01AEA0.1030308@btconnect.com>, <003801c9cfed$3754c170$0301a8c0@mal769a60aa920> X-mailer: Pegasus Mail for Windows (4.41) Content-description: Mail message body X-Cloudmark-Analysis: v=1.0 c=1 a=9YlaCzn6_68A:10 a=Iltcrspv_rvdMazORPQA:9 a=_7RtP6QNr2sxQ_eYtUUA:7 a=wxcR72MS69U4JEhROAw8-MC1-soA:4 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: Re: LF: Re: Re: 500kHz Portable Content-type: text/plain; charset=US-ASCII 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-IP: 193.82.116.20 > You do not need 2 masts for an inv L or T antenna. > The so called horizontal wire(s) can slope down and the far end tied > to a bush or tree, or a stake in the ground via an insulator, as far > away as possible from the vert section, the longer the better. Keep it > simple. mal/g3kev This is quite wrong. Any slope downwards will reduce the effective height of a Marconi. Since ERP is a function of the square of the effective height this is extremely important. An umbrella is far preferable to an inverted-L in a single mast situation because a large amount of capacitance to ground can be achieved without much reduction of effective height. Based on my experience of LF portable (both on 73 and 136kHz), my advice is to make very sure that the remote ends of a Marconi are very well insulated as they carry large voltages. Keep well away from wet trees. This is not just a safety issue; any voltage leaked is power lost. Mike, G3XDV ==========