X-GM-THRID: 1201092871102915278 X-Gmail-Labels: rsgb lf X-Gmail-Received: 23a45e73175fb871863cd4e84e573efb184453da Delivered-To: daveyxm@gmail.com Received: by 10.54.70.6 with SMTP id s6cs27528wra; Fri, 21 Apr 2006 11:56:27 -0700 (PDT) Received: by 10.48.14.6 with SMTP id 6mr335876nfn; Fri, 21 Apr 2006 11:56:27 -0700 (PDT) Return-Path: Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mx.gmail.com with ESMTP id k23si3442nfc.2006.04.21.11.56.26; Fri, 21 Apr 2006 11:56:27 -0700 (PDT) Received-SPF: neutral (gmail.com: 193.82.116.20 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1FX0k4-0001ne-AD for rs_out_1@blacksheep.org; Fri, 21 Apr 2006 19:52:32 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1FX0k3-0001nV-Ua for rsgb_lf_group@blacksheep.org; Fri, 21 Apr 2006 19:52:31 +0100 Received: from mtiwmhc13.worldnet.att.net ([204.127.131.117]) by relay1.thorcom.net with esmtp (Exim 4.51) id 1FX2XM-0002Qj-2F for rsgb_lf_group@blacksheep.org; Fri, 21 Apr 2006 21:47:47 +0100 Received: from [10.0.252.126] (unknown[166.82.181.249]) by worldnet.att.net (mtiwmhc13) with ESMTP id <20060421185210113007ov15e>; Fri, 21 Apr 2006 18:52:10 +0000 Message-ID: <444929D1.50803@att.net> Date: Fri, 21 Apr 2006 14:52:01 -0400 From: Dexter McIntyre W4DEX User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.2) Gecko/20040804 Netscape/7.2 (ax) X-Accept-Language: en-us, en MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <000401c66497$9069f420$e6a4c593@RD40002> <011301c664af$72f94130$0300a8c0@LAPTOP> In-Reply-To: <011301c664af$72f94130$0300a8c0@LAPTOP> X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: Re: LF: Top load coil at ground level? Content-Type: text/plain; charset=us-ascii; format=flowed 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 Status: O X-Status: X-Keywords: X-UID: 6673 Peter Martinez wrote: > > Incidently, Dex, have you thought about removing the wire you have > labelled 'tower grounding wire' and returning the feed to the base of > the tower instead? There should be no voltage between the bottom of the > tower and the bottom of this grounding wire, so you might as well use > the tower to 'ground itself'. Maybe you cannot rely on the tower to > conduct current! > Peter, I initially used this antenna with a single vertical wire and the coil grounded to the base of the tower ground system. I think this is what you described above. There was some discussion about the capacitance between the vertical wire and tower shunting the antenna current to ground so I went looking for a way to feed a short grounded tower. So I found the balanced feed method on Rik's site and give it a try. I tried to make some meaningful field strength measurements between the two methods of feeding the antenna but gave up when I figured out I didn't know what I was doing. Seems I never found a place far enough away from power lines that I could repeat the same levels from day to day with the same antenna. I could even see as much as a 6 db change in signal strength while watching a SLM receiving a steady carrier. These changes could usually be associated with a click or pop which I assume was load changed on the power grid. Conquering this problem is on my list of things to do but right now it's microwave season :) From the signal reports I received with both feeds I could not tell that one way was better than the other. The idea of using coax up the center of the tower is a possibility here. I have a spare rung of 7/8" Heliax that would probably handle the voltage. The tower is well bonded from top to bottom with multiple runs of Heliax and wave guide. Always open for suggestions, Dex, W4DEX / WD2XKO