Return-Path: Received: (qmail 11407 invoked from network); 21 Oct 2002 19:41:10 -0000 Received: from marstons.services.quay.plus.net (212.159.14.223) by mailstore with SMTP; 21 Oct 2002 19:41:10 -0000 Received: (qmail 12170 invoked by uid 10001); 21 Oct 2002 20:47:01 -0000 Received: from post.thorcom.com (193.82.116.70) by marstons.services.quay.plus.net with SMTP; 21 Oct 2002 20:47:01 -0000 Received: from majordom by post.thorcom.com with local (Exim 4.10) id 183iRF-000519-00 for rsgb_lf_group-outgoing@blacksheep.org; Mon, 21 Oct 2002 20:42:09 +0100 Received: from [213.40.2.23] (helo=bodum.sout.netline.net.uk) by post.thorcom.com with esmtp (Exim 4.10) id 183iRE-000510-00 for rsgb_lf_group@blacksheep.org; Mon, 21 Oct 2002 20:42:08 +0100 Received: from [213.40.203.183] (helo=tcs1) by bodum.sout.netline.net.uk with smtp (Exim 4.04) id 183iQj-0001yc-00 for rsgb_lf_group@blacksheep.org; Mon, 21 Oct 2002 20:41:37 +0100 From: "G4WGT" To: "Rsgb_Lf_Group" Date: Mon, 21 Oct 2002 20:42:08 +0100 Message-ID: MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0) X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Importance: Normal Subject: LF: LF Antenna. Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Status: No, hits=0.5 required=5.0tests=SPAM_PHRASE_00_01,TO_LOCALPART_EQ_REAL,USER_AGENT_OUTLOOKversion=2.42 Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Hello to you all, I am at the moment building a 300 watt Tx for 136 Khz, so I need to consider what to do about an Tx antenna for the band. I am receiving with a G3LNP balanced loop & pre-amp. My garden is quite small so the antenna will have to go upwards & give consideration to my neighbours. I have a 30 foot mast with a 4 Mtr beam, a VHF/UHF log periodic beam & VHF/UHF colinear vertical probably going up to 45 feet. I have thought of substituting these for a 6 foot x 2 inch fibreglass pole on top of my mast & using a similar arrangement to that described in the article by Alan Melia G3NYK & Finbar O'Conner EI0CF about spiral top loading. I can also wind inductance on the fibreglass pole to increase the top load inductance. What are your thoughts on this idea & if it sounds ok should I place the additional inductance above or below the spiral & if above what about an additional capacity hat on top of that. I will feed the device with a sloping vertical wire or on stand offs to keep the feed away from the mast & tuned at the bottom with a 12 inch diameter coil & variometer arrangement. Please give me your comments. Regards Gary (G4WGT) --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.401 / Virus Database: 226 - Release Date: 09/10/2002