Return-Path: X-Spam-DCC: paranoid 1290; Body=3 Fuz1=3 Fuz2=3 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-0.7 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, RATWARE_GECKO_BUILD,SPF_PASS autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id u3C9Ie6V010667 for ; Tue, 12 Apr 2016 11:18:40 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1apuOW-0006QD-9e for rs_out_1@blacksheep.org; Tue, 12 Apr 2016 10:14:00 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1apuOV-0006Q4-4j for rsgb_lf_group@blacksheep.org; Tue, 12 Apr 2016 10:13:59 +0100 Received: from smtpout.karoo.kcom.com ([212.50.160.34]) by relay1.thorcom.net with esmtp (Exim 4.87) (envelope-from ) id 1apuOS-0001iW-59 for rsgb_lf_group@blacksheep.org; Tue, 12 Apr 2016 10:13:57 +0100 X-IronPort-AV: E=Sophos;i="5.24,473,1454976000"; d="scan'208";a="160011851" Received: from unknown (HELO [127.0.0.1]) ([109.176.231.201]) by smtpout.karoo.kcom.com with ESMTP; 12 Apr 2016 10:12:47 +0100 Message-ID: <570CBC0D.6000108@lineone.net> Date: Tue, 12 Apr 2016 10:12:45 +0100 From: LineOne User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:31.0) Gecko/20100101 Thunderbird/31.1.2 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <570A7631.5050001@lineone.net> <570B6F37.8060402@lineone.net> <2025D63622D3474489049C563BA6B7AB@gnat> <570BD148.6020103@lineone.net> <570C11FC.6090205@abelian.org> In-Reply-To: <570C11FC.6090205@abelian.org> X-Scan-Signature: e6de17d69e46ff4ea8db042ef2cd7e46 Subject: Re: LF: Re: Screening an LF Loading Coil Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit 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-Scanned-By: MIMEDefang 2.56 on 10.1.3.11 Status: O X-Status: X-Keywords: X-UID: 7673 There were two Powys Amateur radio Club 2m cavity resonators at a commercial transmitter location south of Newtown in Mid wales. They did have a tendency to drift off frequency, probably according to the temperature, being located in an uninsulated, brick hut on the Welsh hillside. The construction probably wasn't up to commercial standards and the weather there was alway wintery, even in the height of summer. The replacements, made by Dave, GW8GLO, have been made with large coaxial cable donated to the club and sit on the back of a 19" rack rear door. It leaves more space in the hut apart from anything else. Hugh, M0DSZ On 11/04/2016 22:07, Paul Nicholson wrote: > > Takes me back to the 1970's when I was a student working for > Gerald David at Aerial Facilities in Chesham building these > things - > > http://www.ingenia.org.uk/Ingenia/Articles/240 > > which worked incredibly well thanks to the ingenuity of some > people at Bradford Uni who designed the adjustable center > conductor of the cavity so that the overall temperature > coefficient of the 'barrel' as we called the cavities, was close > to zero. Bandwidths of a few kHz at VHF with insertion loss > of less than 1dB were normal. > > Gerald was a wonderful larger than life character, I could > relate many stories about life at AFL in those days - not > least Gerald's specialised driving techniques applied to the > country lanes of Buckinghamshire. There were many jokes about > ensuring the barrels were empty and Friday lunchtimes at the > pub were generally devoted to that. > > -- > Paul Nicholson > -- > >