Return-Path: Received: (qmail 4795 invoked from network); 19 Apr 2003 18:14:06 -0000 Received: from murphys.services.quay.plus.net (212.159.14.225) by mailstore with SMTP; 19 Apr 2003 18:14:06 -0000 Received: (qmail 25900 invoked from network); 19 Apr 2003 18:13:53 -0000 Received: from post.thorcom.com (193.82.116.70) by murphys.services.quay.plus.net with SMTP; 19 Apr 2003 18:13:53 -0000 X-SQ: A Received: from majordom by post.thorcom.com with local (Exim 4.14) id 196wpT-0005t3-UQ for rsgb_lf_group-outgoing@blacksheep.org; Sat, 19 Apr 2003 19:12:47 +0100 Received: from [212.135.6.11] (helo=smarthost1.mail.uk.easynet.net) by post.thorcom.com with esmtp (Exim 4.14) id 196wpP-0005su-AF for rsgb_lf_group@blacksheep.org; Sat, 19 Apr 2003 19:12:43 +0100 Received: from tnt-2-211.easynet.co.uk ([195.40.196.211] helo=erica) by smarthost1.mail.uk.easynet.net with smtp (Exim 4.10) id 196wpM-000Bkj-00 for rsgb_lf_group@blacksheep.org; Sat, 19 Apr 2003 19:12:42 +0100 Message-ID: <000001c3069f$f862d820$d3c428c3@erica> From: "g3ldo" To: rsgb_lf_group@blacksheep.org References: <000201c3058c$45093ee0$f9e4fc3e@l8p8y6> <001601c305dd$95539520$f2d0fc3e@ian> Date: Sat, 19 Apr 2003 14:33:05 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4522.1200 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Subject: LF: BK amps Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Status: No, hits=-6.3 required=5.0tests=DATE_IN_PAST_03_06,REFERENCESversion=2.53 X-Spam-Checker-Version: SpamAssassin 2.53 (1.174.2.15-2003-03-30-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 Hi Ian, In the early days of 73kHz many of us were using the BK amplifier and during these experiments in trying to get maximum power into the antenna many fuses and FETs were blown. Lech Laszkiewicz, G3KAU, made a series of modifications to provide protection and monitoring of the FETs in the BK amplifier while experimenting with antennas. These mods were described in the revised edition of 'The LF Experimenter's Source Book', the forerunner of 'The Low Frequency Experimenter's Handbook' While browsing through the source book I came across the reprint of the Nov 1997 RadCom article, which described the first QRSS test. The test transmission by G4JNT in Southhampton, using an output power of 1mW and 80 sec dots on 73kHz, was received by G3PLX in Kendal, Cumbria, a distance of 393km. The technique seemed rather esoteric at the time and little did we realise it would be come the dominant mode on LF. Regards, Peter, G3LDO e-mail Web