Return-Path: Received: (qmail 25762 invoked from network); 15 Jul 2001 08:30:10 -0000 Received: from unknown (HELO warrior-inbound.servers.plus.net) (212.159.14.227) by excalibur-qfe1-smtp-plusnet.harl.plus.net with SMTP; 15 Jul 2001 08:30:10 -0000 Received: (qmail 1391 invoked from network); 15 Jul 2001 08:29:14 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by warrior with SMTP; 15 Jul 2001 08:29:14 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.16 #2) id 15Lh9U-0007Cu-00 for rsgb_lf_group-outgoing@blacksheep.org; Sun, 15 Jul 2001 09:21:20 +0100 Received: from irwell.zetnet.co.uk ([194.247.47.48] helo=zetnet.co.uk ident=root) by post.thorcom.com with esmtp (Exim 3.16 #2) id 15Lh9T-0007Cp-00 for rsgb_lf_group@blacksheep.org; Sun, 15 Jul 2001 09:21:19 +0100 Received: from abc (man-s247.dialup.zetnet.co.uk [194.247.45.118]) by zetnet.co.uk (8.11.3/8.11.3/Debian 8.11.2-1) with SMTP id f6F8KWW30722 for ; Sun, 15 Jul 2001 09:20:33 +0100 Message-ID: <000901c10d06$d678f260$762df7c2@zetnet.co.uk> From: "John Rabson" To: rsgb_lf_group@blacksheep.org References: <004601c10cb2$a9e5b480$828801d4@g4jnt> Subject: LF: GBR (was 9kHz NOVs) Date: Sun, 15 Jul 2001 09:18:09 +0100 MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.00.2919.6600 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: ----- Original Message ----- From: "Andrew Talbot" To: Sent: Saturday, July 14, 2001 11:16 PM Subject: LF: Re: re 9kHz NOVs > Rugby at one time in its > history running a few 10s of kW was reckoned to have 500000 Volts on its > antenna. > Sounds a bit high. According to Watt (VLF Radio Engineering, end of chapter 2), Rugby is voltage-limited below about 21 kHz. From the figures he gives for the post-1958 configuration I estimate the feed current as 500 to 600 A. If I interpret his graphs correctly, the reactance of the aerial (and therefore of the resonating helix) is about 200 ohms. This indicates a maximum voltage on the top hat in the region of 100 to 120 kV. One of Watt's graphs shows a figure of 165 kV as the voltage-limited figure for the original 8-tower array. 73 de John Rabson G3PAI