Return-Path: Received: (qmail 21253 invoked from network); 30 Jul 1999 17:45:07 +0100 Received: from magnus.plus.net.uk (HELO magnus.force9.net) (195.166.128.27) by guiness.force9.net with SMTP; 30 Jul 1999 17:45:07 +0100 Received: (qmail 24584 invoked from network); 30 Jul 1999 13:00:46 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by magnus.plus.net.uk with SMTP; 30 Jul 1999 13:00:46 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.02 #1) id 11AC6V-0005UF-00 for rsgb_lf_group-outgoing@blacksheep.org; Fri, 30 Jul 1999 13:49:39 +0100 Received: from mserv1a.u-net.net ([195.102.240.34]) by post.thorcom.com with esmtp (Exim 3.02 #1) id 11AC6S-0005Tu-00 for rsgb_lf_group@blacksheep.org; Fri, 30 Jul 1999 13:49:36 +0100 X-Priority: 3 X-MSMail-Priority: Normal Received: from rsgb.u-net.com ([195.102.80.225] helo=rsgb.org.uk) by mserv1a.u-net.net with smtp (Exim 2.10 #61) id 11AC6w-000557-00 for rsgb_lf_group@blacksheep.org; Fri, 30 Jul 1999 13:50:07 +0100 Received: from miked.rsgbhq [192.168.2.30] by rsgb.org.uk [192.168.2.132] with SMTP (MDaemon.v2.7.SP5.R) for ; Fri, 30 Jul 1999 13:45:46 +0100 From: "Mike Dennison" X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Organization: Radio Society of Great Britain To: rsgb_lf_group@blacksheep.org Date: Fri, 30 Jul 1999 13:48:08 +0100 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 8bit Subject: Re: LF: A burning affair In-reply-to: <000e01beda86$23dcd360$0a97b38f@w8k3f0> X-Mailer: Pegasus Mail for Win32 (v3.01d) X-MDaemon-Deliver-To: rsgb_lf_group@blacksheep.org X-Return-Path: miked@mail.rsgbhq Message-ID: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org Sender: PA0SE wrote: > It all goes to show how important the insulation of the aerial at LF is. It has been said and written before over and over again but > it seems that an experience like I had is needed to really burn it in! > Agreed. I have had several flash-overs, including setting fire to a plastic drain pipe which I had assumed was made of an insulating material (brand new conservatory - not a popular thing to do!). It is possible with an MF antenna to run the wire over a tree branch, but not at LF. Even coming close to a leaf can cause sparks, smoke and flames. The problem is so bad that the (UK) Admiralty Handbook of 1926 (highly recommended for practical LF work) specifies a maximum current, above which the corona discharge at the end of the antenna dissipates any additional power! This is higher power than we run, but not a lot. So good insulation is vital, not only for best efficiency, but also for saftey. Mike, G3XDV (IO91VT) http://www.dennison.demon.co.uk/activity.htm