Return-Path: Received: from rly-dd04.mx.aol.com (rly-dd04.mail.aol.com [172.19.141.151]) by air-dd06.mail.aol.com (v123.4) with ESMTP id MAILINDD063-b764a09a19a1c7; Tue, 12 May 2009 12:19:47 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-dd04.mx.aol.com (v123.4) with ESMTP id MAILRELAYINDD048-b764a09a19a1c7; Tue, 12 May 2009 12:19:40 -0400 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1M3ugx-00047e-1T for rs_out_1@blacksheep.org; Tue, 12 May 2009 17:18:55 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1M3ugw-00047V-KG for rsgb_lf_group@blacksheep.org; Tue, 12 May 2009 17:18:54 +0100 Received: from smtp5.freeserve.com ([193.252.22.159]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1M3ugt-0001u2-O0 for rsgb_lf_group@blacksheep.org; Tue, 12 May 2009 17:18:53 +0100 Received: from me-wanadoo.net (localhost [127.0.0.1]) by mwinf3401.me.freeserve.com (SMTP Server) with ESMTP id 7FB781C00082 for ; Tue, 12 May 2009 18:18:36 +0200 (CEST) Received: from AGB (unknown [91.109.12.252]) by mwinf3401.me.freeserve.com (SMTP Server) with SMTP id F11421C00081 for ; Tue, 12 May 2009 18:18:33 +0200 (CEST) X-ME-UUID: 20090512161833987.F11421C00081@mwinf3401.me.freeserve.com Message-ID: <700020F556AB40A68EFAC71AAC736810@AGB> From: "Graham" To: References: <4A01AEA0.1030308@btconnect.com>, <003801c9cfed$3754c170$0301a8c0@mal769a60aa920> <4A094F88.31094.2E46CD4@mike.dennison.ntlworld.com> In-Reply-To: <4A094F88.31094.2E46CD4@mike.dennison.ntlworld.com> Date: Tue, 12 May 2009 17:18:23 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 14.0.8064.206 X-MimeOLE: Produced By Microsoft MimeOLE V14.0.8064.206 X-Karma: unknown: X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: Re: LF: Re: Re: 500kHz Portable Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original 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=0.1 required=5.0 tests=MISSING_OUTLOOK_NAME 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 Yes your right on that Mike, If you model a T and then change it to arrow shape , once the free ends are more than about 6 feet off the ground the radiation and feed values are all over the place ..you would not of realised in the field, what was going on ! G . -------------------------------------------------- From: "Mike Dennison" Sent: Tuesday, May 12, 2009 10:29 AM To: Subject: Re: LF: Re: Re: 500kHz Portable > >> 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 > ========== > > > > > No virus found in this incoming message. > Checked by AVG - www.avg.com > Version: 8.5.287 / Virus Database: 270.12.24/2107 - Release Date: 05/10/09 > 07:02:00 >