Return-Path: <majordom@post.thorcom.com> Received: (qmail 7805 invoked from network); 15 Jan 2001 10:10:15 -0000 Received: from unknown (HELO murphys-inbound.servers.plus.net) (212.159.14.225) by excalibur.plus.net with SMTP; 15 Jan 2001 10:10:15 -0000 Received: (qmail 10335 invoked from network); 15 Jan 2001 10:04:40 -0000 Content-Transfer-Encoding: 8bit Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by murphys with SMTP; 15 Jan 2001 10:04:41 -0000 X-Priority: 3 X-MSMail-Priority: Normal Received: from majordom by post.thorcom.com with local (Exim 3.16 #1) id 14I6OR-0005Tk-00 for rsgb_lf_group-outgoing@blacksheep.org; Mon, 15 Jan 2001 09:57:39 +0000 Received: from fm215.facility.pipex.com ([194.131.104.225]) by post.thorcom.com with esmtp (Exim 3.16 #1) id 14I6OO-0005Tf-00 for rsgb_lf_group@blacksheep.org; Mon, 15 Jan 2001 09:57:36 +0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from 233.pncl.co.uk (107.235.35.212.in-addr.arpa.ip-pool.cix.co.uk [212.35.235.107]) by fm215.facility.pipex.com (8.9.3/8.9.3) with ESMTP id JAA01940 for <rsgb_lf_group@blacksheep.org>; Mon, 15 Jan 2001 09:53:01 GMT Message-ID: <5.0.2.1.2.20010115093244.00a18b40@mail.pncl.co.uk> X-Sender: blanch@mail.pncl.co.uk X-Mailer: QUALCOMM Windows Eudora Version 5.0.2 Date: Mon, 15 Jan 2001 09:41:20 +0000 To: rsgb_lf_group@blacksheep.org From: "Walter Blanchard" <blanch@pncl.co.uk> Subject: Re: LF: coil screening In-reply-to: <C6ABA8DEC115D311A29D00105ABD3264A96BBD@nmex01nt.hsd.utc.co m> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: <majordom@post.thorcom.com> Gamal says it all. It was impossible to keep the Decca coils tuned accurately and maintain phase constancy without the copper screening. Even then there had to be an automatic re-tuning device for when nearby lightning strikes made the coils jump. It was driven by a small electric motor and a belt/pulley arrangement that moved a little subsidiary coil back and forth a few inches. Occasionally there was a direct lightning strike on the antenna usually resulting in the belt jumping off the pulleys and a panic callout for the duty engineer. And for Bob, VE7BS - no, there was nothing in the hut except the loading coils - it was only about 5 x 5 metres. Walter G3JKV.