Return-Path: <owner-rsgb_lf_group@blacksheep.org> Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-da06.r1000.mx.aol.com (Internet Inbound) with ESMTP id 6CCAA3800008A; Mon, 19 Dec 2011 06:07:22 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Rcb2o-0002sB-OL for rs_out_1@blacksheep.org; Mon, 19 Dec 2011 11:06:10 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Rcb2o-0002s2-61 for rsgb_lf_group@blacksheep.org; Mon, 19 Dec 2011 11:06:10 +0000 Received: from out1.ip03ir2.opaltelecom.net ([62.24.128.239]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from <g3kevmal@talktalk.net>) id 1Rcb2m-0000NW-Lg for rsgb_lf_group@blacksheep.org; Mon, 19 Dec 2011 11:06:10 +0000 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: Ai4BAKEZ705Ok8jA/2dsb2JhbABDmxKPHIEwgQaBbQUBAQQBCAEBA0kCJgYBAQMFAgEDEQQBAQolFAEEGgYWCAYTCgECAgEBh2kCt32IaoMaBIgDhQEpAZl+ X-IronPort-AV: E=Sophos;i="4.71,375,1320624000"; d="scan'208";a="370021449" Received: from host-78-147-200-192.as13285.net (HELO xphd97xgq27nyf) ([78.147.200.192]) by out1.ip03ir2.opaltelecom.net with SMTP; 19 Dec 2011 11:06:02 +0000 Message-ID: <000901ccbe3e$31cd2700$0401a8c0@xphd97xgq27nyf> From: "mal hamilton" <g3kevmal@talktalk.net> To: <rsgb_lf_group@blacksheep.org> References: <CAA8k23Rn9WpQM3Ukf=cq5-bLmWy+o4SEsH2abf7cAX=BpLWExQ@mail.gmail.com> <op.v6k16ktpyzqh0k@pc-roelof> <033201ccbcab$5c5fe640$1502a8c0@Clemens04> <op.v6mtuugnyzqh0k@pc-roelof> <000901ccbcc4$42768fe0$c763afa0$@com> <4EECC1E8.4000806@iup.uni-heidelberg.de> <002c01ccbd6f$572761c0$0401a8c0@xphd97xgq27nyf> <39D91133A64A480596FBAA4395D85812@JimPC> <007901ccbd9e$69fe2ed0$0401a8c0@xphd97xgq27nyf> <08C805D2A1C04E64836275C632577CF2@JimPC> Date: Mon, 19 Dec 2011 11:06:01 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: LF: Re: Re: TX system at DK7FC, schematic Content-Type: text/plain; charset="iso-8859-1" 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-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:507196192:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d404e4eef1aea3010 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none Hi Jim es LF My LF loading coil as described recently is wound with ex Decca litz 729 strand wire wound on a semi air spaced plastic basket I avoid using a variometer which would degrade the main coil Q mala/g3kev ----- Original Message ----- From: "James Moritz" <james.moritz@btopenworld.com> To: <rsgb_lf_group@blacksheep.org> Sent: Monday, December 19, 2011 9:36 AM Subject: LF: Re: TX system at DK7FC, schematic > Dear Mal, LF Group, > > > The highest Q coils I have seen are self supporting encased in a helium > > container and the Q specified was only in a few hundred. What sort of coil > > construction yields 4000 and above ? > > I have yet to encounter such a specimen > > Errm.... The sort of specimen shown in the picture you sent to everyone > yesterday, i.e., a coil a few metres in diameter wound using very large litz > wire. > > The highest Q LF coil I have made so far had 109 turns of 729-strand litz > wire wound on a plastic former about 400mm diameter. L was about 4mH and Q > measured at 1100. Stefan's loading coil uses similar construction and has > similar Q. A coil of similar size and inductance wound with PVC insulated > copper wire had a Q of only about 300. > > For a given inductance and type of construction, Q increases with size, but > only slowly. The size required to reach a given Q seems to reduce fairly > slowly with increasing frequency. This is part of the reason for VLF loading > coils being so large. The "helium coils" were discussed on this reflector > some time ago - they were loading coils for HF mobile whips. A Q of a few > hundred for a fairly large coil is not remarkable; obviously, the size of > coil is limited for a practical mobile whip. The helium was just a sales > gimmick that would make no significant difference to Q. > > Cheers, Jim Moritz > 73 de M0BMU > >