X-GM-THRID: 1201102839163249103 X-Gmail-Labels: rsgb lf X-Gmail-Received: 3f919c90c1785574dcbde8b889c0f641f89ba700 Delivered-To: daveyxm@gmail.com Received: by 10.54.70.6 with SMTP id s6cs20672wra; Wed, 19 Apr 2006 12:37:05 -0700 (PDT) Received: by 10.48.164.6 with SMTP id m6mr43491nfe; Wed, 19 Apr 2006 12:37:05 -0700 (PDT) Return-Path: Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mx.gmail.com with ESMTP id b1si1819457nfe.2006.04.19.12.37.04; Wed, 19 Apr 2006 12:37:05 -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 1FWIRq-0001Bf-4e for rs_out_1@blacksheep.org; Wed, 19 Apr 2006 20:34:46 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1FWIRp-0001BW-MD for rsgb_lf_group@blacksheep.org; Wed, 19 Apr 2006 20:34:45 +0100 Received: from bay116-f12.bay116.hotmail.com ([64.4.38.22] helo=hotmail.com) by relay1.thorcom.net with esmtp (Exim 4.51) id 1FWKEK-0001sv-K9 for rsgb_lf_group@blacksheep.org; Wed, 19 Apr 2006 22:29:15 +0100 Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Wed, 19 Apr 2006 12:34:20 -0700 Message-ID: Received: from 64.4.38.200 by by116fd.bay116.hotmail.msn.com with HTTP; Wed, 19 Apr 2006 19:34:16 GMT X-Originating-IP: [138.32.32.44] X-Originating-Email: [hellozerohellozero@hotmail.com] X-Sender: hellozerohellozero@hotmail.com In-Reply-To: <8bf118410604190831m5288a772idf16b24c9ca416b9@mail.gmail.com> From: "Laurence KL1X" To: rsgb_lf_group@blacksheep.org Bcc: Date: Wed, 19 Apr 2006 11:34:16 -0800 Mime-Version: 1.0 X-OriginalArrivalTime: 19 Apr 2006 19:34:20.0545 (UTC) FILETIME=[41482F10:01C663E8] X-Spam-Score: -1.2 (-) X-Spam-Report: autolearn=disabled,AWL=-1.206,MSGID_FROM_MTA_HEADER=0 Subject: RE: LF: Loop experiments in GM Content-Type: text/plain; format=flowed X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.8 required=5.0 tests=MSGID_FROM_MTA_HEADER 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: 5890 Nice one Dave! People want want to take a look at Johns XES web site and other coupler info for loops too - the Sangamo series are commonly used especially the bigger G2 or 3 size (!) search under ebay Sangamo mica and normally youll find one or two available. http://www.w1tag.com/XESANT.htm http://myweb.cableone.net/flow/copper3.jpg Just heard XDW will be up rooting again in the autumn - but I hope not to have wasted my 55 bucks with the FCC and determined to get a signal out from this location before I move again...dont ask me where as they wont tell me...just that Im moving...Im kneeling to the East and hope its going back to KL7... Laurence KL1X in Okie >From: "Dave Pick" >Reply-To: rsgb_lf_group@blacksheep.org >To: "LF Group" >Subject: LF: Loop experiments in GM >Date: Wed, 19 Apr 2006 16:31:47 +0100 > >Dear all. > >Well I got the loop working pretty well at the GM QTH (20 miles West of >Dumfries SW Scotland). It ran N/S and was made of 5mm OD coax cable pulled >through two trees 100ft apart. At one end it was about 60ft high and the >other about 50 although the top was horizontal (ground higher at the South >end). To get the right circumference of about 330ft the bottom span was >longer than the top and was about 4 to 5ft high. The tuner was placed in >the >centre of the bottom span standing on an upturned stacking box (so 2ft off >the ground). >The 12nF required to tune the loop was made up of 100 1nF 2kV >polypropylene "pulse rated" Cs connected in 33 parallel legs each having 3 >series Cs (333pF each leg). That gives almost 11nF, across this was a 2nF >vacuum variable C motor-driven from the shack. >Current in the loop was calculated at over 30A and measured at about 35. >This means each C was passing around 1A. The frequency did move slightly HF >under long periods of QRSS and the heating of the Cs could be felt by hand >but they were by no means hot. I guess they have a negative temperature >coefficient? >The transformer was made of 3 stacked 58mm 3C85 toroids with 20 turns on >the >primary and two turns of huge fat "starter motor" type cable as the >secondary in series with the loop and Cs. The transformer remained >completely stone cold even at 1kW input. I think I over-engineered it a bit >after some tales of over heating from the states! >Over the four days I worked 7 countries with "O" reports including OH1TN >off >the side of the loop. >Later, when the weather improved I got out the trusty bow and arrow again >and put up a nice Marconi inverted L with a 120ft top at 65ft high and a 45 >degree downlead of about 90ft. >Due to the poor ground and proximity to trees I could only get 2.5A up this >wire with 1kW, my best efforts on this site in the past gave over 3A (more >top wires, more radials). Nevertheless the Marconi gave exactly the same >signal reports with G3NYK, G3KEV and G3AQC with whom I did tests. It was, >however, much noisier on receive. Every station I heard, regardless of >direction, was better copy on the loop. >I also took the PA0DRT mini-whip with me and on a 20ft pole it was easily >as >sensitive as the big aerials, slightly less noisy than the Marconi but not >as quiet as the loop. > >So the loop was easy to erect, no worries about wires touching branches, >robust due to the thick cable, performed as well as a similar Marconi on TX >and was quiet on receive. >On the negative side the lower element gets in the way and it required a >specialist tuner... but now I've got one I could be using loops more often! > >I've left both aerials up for the next visit but I know which one is more >likely to withstand the gales... > >This and the pictures are at http://wireless.org.uk/loopy.htm >-- >G3YXM IO92BK Birmingham UK (was IO75WC in GM)