Return-Path: Received: (qmail 23621 invoked from network); 1 Apr 2003 14:36:30 -0000 Received: from warrior.services.quay.plus.net (212.159.14.227) by mailstore with SMTP; 1 Apr 2003 14:36:30 -0000 Received: (qmail 5597 invoked from network); 1 Apr 2003 14:36:33 -0000 Received: from post.thorcom.com (193.82.116.70) by warrior.services.quay.plus.net with SMTP; 1 Apr 2003 14:36:33 -0000 X-SQ: A Received: from majordom by post.thorcom.com with local (Exim 4.14) id 190MoU-0007SH-Bl for rsgb_lf_group-outgoing@blacksheep.org; Tue, 01 Apr 2003 15:32:34 +0100 Received: from [194.73.73.176] (helo=protactinium.btinternet.com) by post.thorcom.com with esmtp (Exim 4.14) id 190MoP-0007S5-Fp for rsgb_lf_group@blacksheep.org; Tue, 01 Apr 2003 15:32:29 +0100 Received: from host81-132-170-52.in-addr.btopenworld.com ([81.132.170.52] helo=dellboy) by protactinium.btinternet.com with smtp (Exim 3.22 #23) id 190MoP-00018v-00 for rsgb_lf_group@blacksheep.org; Tue, 01 Apr 2003 15:32:29 +0100 Message-ID: <00b701c2f85b$b12fafc0$1b00a8c0@dellboy> From: "Dave Pick" To: rsgb_lf_group@blacksheep.org References: <000501c2f7a3$1f8d9ea0$07d2fc3e@ian> <003101c2f7b3$1954f500$cbe8fc3e@l8p8y6> Date: Tue, 1 Apr 2003 15:33:40 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Subject: LF: Re: Re: Frustration! Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Status: No, hits=-9.1 required=5.0tests=BANG_MONEY,QUOTED_EMAIL_TEXT,REFERENCESversion=2.51 X-Spam-Checker-Version: SpamAssassin 2.51 (1.174.2.5-2003-03-20-exp) X-SA-Exim-Scanned: Yes Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rsgb_lf_group-outgoing@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false Mal said... > > NEVER put your loading coil in a metal box, it totally destroys the > efficiency. Consider it as part of the antenna from the radiation point of > view. You have never seen a loading coil on a Mobile encased in a metal CAN, > the coil contributes to the over all efficiency ie coil plus whip. I hope somebody tells the BBC and other broadcasters not to put their loading coils in metal shielded "ATH"s because they will keep doing it! If you think they aren't worried about efficiency, think again! Inefficiency at QRO = heat and MONEY!!! For what it's worth I put my coil in a metal clad shed in the garden and the aerial current INCREASED to the effect of about 1dB improvement. The coil is so small as to be an insignificant part of the radiating system, losses are everything and losses due to the coil's electrostatic field coupling into trees etc can be significant. If you coil isn't out in the clear you may benefit from doing it but it has to be done well, dodgy joints etc will lose you more than you gain. As for receive noise...... have you listened on LF much? Dave G3YXM.