Return-Path: Received: (qmail 17538 invoked from network); 4 Apr 1999 16:38:49 +0100 Received: from magnet.plus.net.uk (HELO magnet.force9.net) (195.166.128.26) by guiness.force9.net with SMTP; 4 Apr 1999 16:38:49 +0100 Received: (qmail 32365 invoked from network); 4 Apr 1999 15:39:25 -0000 Received: from post.thorcom.com (194.75.130.70) by magnet.plus.net.uk with SMTP; 4 Apr 1999 15:39:25 -0000 Content-Transfer-Encoding: 8bit Received: from troy.blacksheep.org ([194.75.183.50] ident=root) by post.thorcom.com with esmtp (Exim 2.04 #3) id 10Tos1-00041k-01; Sun, 4 Apr 1999 16:31:34 +0100 Received: (from root@localhost) by troy.blacksheep.org (8.6.12/8.6.12) id PAA30146 for rsgb_lf_group-outgoing; Sun, 4 Apr 1999 15:31:11 GMT X-Priority: 3 X-MSMail-Priority: Normal Received: from post.thorcom.com (root@post.unica.co.uk [194.75.183.70]) by troy.blacksheep.org (8.6.12/8.6.12) with ESMTP id PAA30142 for ; Sun, 4 Apr 1999 15:31:09 GMT Received: from premium.inrete.it ([194.116.9.4] helo=mailer.inrete.it) by post.thorcom.com with esmtp (Exim 2.04 #3) id 10Tor8-00041O-00 for rsgb_lf_group@blacksheep.org; Sun, 4 Apr 1999 16:30:39 +0100 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from pc-lab (pcttym02.inrete.it [194.116.9.246]) by mailer.inrete.it (8.8.8/8.8.8) with SMTP id RAA21195 for ; Sun, 4 Apr 1999 17:30:31 +0200 Message-ID: <3.0.3.32.19990404162448.0068a010@mailer.inrete.it> X-Sender: spin@mailer.inrete.it X-Mailer: QUALCOMM Windows Eudora Light Version 3.0.3 (32) Date: Sun, 04 Apr 1999 16:24:48 +0100 To: rsgb_lf_group@blacksheep.org From: "M. Bruno" Subject: LF: New loading coil operative, new top hat... In-reply-to: <199904031449_MC2-7082-9C31@compuserve.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org Hi all, I have rebuilt my loading coil/variometer, using a plastic dustbin as support. It works very well, and the antenna current even increased a bit, from abt. 5,8 to 6 A. Thanks to all OMs for their suggestions! I extimate the ERP increase in 0,7 dB. Details of the coil: I have an antenna capacitance of 370 pF, requiring about 3,7 mH to be tuned. The coil has 100 turns of insulated 12 AWG wire (2 mm dia., abt 3 mm with insulation). The wire is a surplus one, and insulation is hard plastics, probably siliconic (definitively not PVC). The winding is conic, diameter abt. 450 mm at the base, 425 mm at top. The variometer has 10 turns on 300 mm dia, and is mounted on the high (and hot) side for easy of turning. According to G4FGQ's SOLENOID.EXE the Q should be over 1100 when in series resonance. Assuming a 3 Ohm series resistance (3,1 kOhm reactance) the dissipated power in the inductor should be about 100 W. After 30 seconds of key down or 6 minutes of CQ the coil warms a little, so I have to believe that Q is high! Then I am rebuilding the top hat. Currently I use two 27 m wires, spaced 1 m. The new one has three 20 m wires, spaced 1 m from each other. It will be more distant from obstacles (house and end pole). I hope to be QRV tomorrow. 73 de IK1ODO Marco Rivalta, ITALY JN35SA (N 45 01' 25.6", E 7 31' 09.4")