X-GM-THRID: 1208103695741282520 X-Gmail-Labels: rsgb lf X-Gmail-Received: 622f0d3445ddd0650417fbc77ff12dfb7e5eb6bc Delivered-To: daveyxm@gmail.com Received: by 10.64.249.17 with SMTP id w17cs141289qbh; Wed, 5 Jul 2006 15:57:18 -0700 (PDT) Received: by 10.48.47.3 with SMTP id u3mr15685nfu; Wed, 05 Jul 2006 15:57:18 -0700 (PDT) Return-Path: Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mx.gmail.com with ESMTP id m16si5922208nfc.2006.07.05.15.57.17; Wed, 05 Jul 2006 15:57:18 -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 1FyGHB-0003Op-Hp for rs_out_1@blacksheep.org; Wed, 05 Jul 2006 23:55:21 +0100 Received: from [193.82.59.130] (helo=relay2.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1FyGHB-0003Og-3k for rsgb_lf_group@blacksheep.org; Wed, 05 Jul 2006 23:55:21 +0100 Received: from smtp805.mail.ukl.yahoo.com ([217.12.12.195]) by relay2.thorcom.net with smtp (Exim 4.51) id 1FyGH5-0002ja-6u for rsgb_lf_group@blacksheep.org; Wed, 05 Jul 2006 23:55:20 +0100 Received: (qmail 99456 invoked from network); 5 Jul 2006 22:54:09 -0000 Received: from unknown (HELO w4o8m9) (james.moritz@btopenworld.com@213.122.12.216 with login) by smtp805.mail.ukl.yahoo.com with SMTP; 5 Jul 2006 22:54:09 -0000 Received: from 127.0.0.1 (AVG SMTP 7.1.394 [268.9.9/382]); Wed, 05 Jul 2006 23:51:35 +0100 Message-ID: <002501c6a085$912d56c0$d80c7ad5@w4o8m9> From: "James Moritz" To: References: Date: Wed, 5 Jul 2006 23:51:35 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.00.2615.200 X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2615.200 X-Spam-Score: 0.4 (/) X-Spam-Report: autolearn=disabled,AWL=-2.243,RCVD_IN_NJABL_PROXY=1.026,RCVD_IN_SORBS_MISC=1.597 Subject: LF: Re: LF loading coils 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 Status: O X-Status: X-Keywords: X-UID: 5001 > > I haven't tried a short, fat loading coil yet, but the indications are that > short fat coils have lower losses. > > 73, Dave G3WCB IO91RM Dear Dave, LF group, Short, fat coils wound with the same type of wire, and other losses being negligible, do indeed have higher Q (at least, until they get really short and fat - the optimum figure is usually given diameter = 2.5 x length; after that Q starts to go down again). But don't get too carried away, because the winding has to support the same voltage, and the shorter winding will have greater voltage between adjacent turns, putting the insulation under greater dielectric strain, which can certainly be a problem with a high voltage antenna system. Assuming actual breakdown does not occur, dielectric losses in the wire insulation and the former, will increase. If the former or insulation is made of some relatively lossy dielectric, for example PVC, it is certainly possible to end up with a shorter, fatter coil with reduced Q - as I proved experimentally once, much to my annoyance! Cheers, Jim Moritz 73 de M0BMU