Return-Path: Received: from mtain-dl01.r1000.mx.aol.com (mtain-dl01.r1000.mx.aol.com [172.29.74.207]) by air-me03.mail.aol.com (v129.4) with ESMTP id MAILINME033-8baa4d449e94247; Sat, 29 Jan 2011 18:11:16 -0500 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dl01.r1000.mx.aol.com (Internet Inbound) with ESMTP id 73795380000A5; Sat, 29 Jan 2011 18:11:14 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1PjJvr-0007QG-GS for rs_out_1@blacksheep.org; Sat, 29 Jan 2011 23:10:15 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1PjJvr-0007Q7-1N for rsgb_lf_group@blacksheep.org; Sat, 29 Jan 2011 23:10:15 +0000 Received: from vader.london.02.net ([82.132.130.150] helo=mail.o2.co.uk) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1PjJvo-0003K9-GG for rsgb_lf_group@blacksheep.org; Sat, 29 Jan 2011 23:10:15 +0000 Received: from [192.168.1.65] (46.64.39.147) by mail.o2.co.uk (8.5.119.05) (authenticated as g3ldo@o2.co.uk) id 4CB23F221C116B5B for rsgb_lf_group@blacksheep.org; Sat, 29 Jan 2011 23:20:25 +0000 Message-ID: <4D449E50.2020507@o2.co.uk> Date: Sat, 29 Jan 2011 23:10:08 +0000 From: Peter Dodd User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-GB; rv:1.9.2.13) Gecko/20101207 Thunderbird/3.1.7 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: In-Reply-To: X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,RATWARE_GECKO_BUILD=1.426 Subject: LF: LF coil tuning Content-Type: text/plain; charset=ISO-8859-1; 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 x-aol-global-disposition: G x-aol-sid: 3039ac1d4acf4d449e923856 X-AOL-IP: 195.171.43.25 X-Mailer: Unknown (No Version) The traditional method of tuning an LF loading coil is to use a variometer. I have been investigating methods of tuning coils for mobile use and one method that appeared briefly in one of the ARRL Handbooks of the 50s was the shorted turn method of tuning. I tried a home made coil of 136uH on a 5cm diameter former and using a shorted turn of 2mm insulated wire and obtained a tuning range of 32uH. (136 - 102uH). Has anyone out there tried this? Regards Peter G3LDO