Return-Path: Received: (qmail 5542 invoked from network); 15 Jan 2001 12:59:26 -0000 Received: from unknown (HELO warrior-inbound.servers.plus.net) (212.159.14.227) by 10.226.25.101 with SMTP; 15 Jan 2001 12:59:26 -0000 Received: (qmail 20897 invoked from network); 15 Jan 2001 13:02:50 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by warrior with SMTP; 15 Jan 2001 13:02:50 -0000 Content-Transfer-Encoding: 8bit Received: from majordom by post.thorcom.com with local (Exim 3.16 #1) id 14I9Ae-0006NW-00 for rsgb_lf_group-outgoing@blacksheep.org; Mon, 15 Jan 2001 12:55:36 +0000 Received: from bob.dera.gov.uk ([192.5.29.90]) by post.thorcom.com with esmtp (Exim 3.16 #1) id 14I9Ab-0006NR-00 for rsgb_lf_group@blacksheep.org; Mon, 15 Jan 2001 12:55:33 +0000 X-Priority: 3 X-MSMail-Priority: Normal Received: by bob.dera.gov.uk; (8.8.8/1.3/10May95) id MAA25585; Mon, 15 Jan 2001 12:56:36 GMT Received: (qmail 29708 invoked from network); 15 Jan 2001 13:49:19 -0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from gauntlet.mail.dera.gov.uk (172.16.9.10) by baton.dera.gov.uk with SMTP; 15 Jan 2001 13:49:19 -0000 Received: by gauntlet.mail.dera.gov.uk; id NAA09719; Mon, 15 Jan 2001 13:41:22 GMT Received: from unknown(10.71.64.31) by gauntlet.mail.dera.gov.uk via smap (3.2) id xma009652; Mon, 15 Jan 01 13:40:55 GMT Received: from FRN-MAIL-3.dera.gov.uk (unverified) by mailguard.dera.gov.uk (Content Technologies SMTPRS 4.1.5) with ESMTP id for ; Mon, 15 Jan 2001 12:57:53 +0000 Received: by frn-mail-3.dera.gov.uk with Internet Mail Service (5.5.2650.21) id ; Mon, 15 Jan 2001 12:55:02 -0000 Message-ID: <65AECDF1F89AD411900400508BFC869F0D7512@pdw-mail-1.dera.gov.uk> From: "Talbot Andrew" To: rsgb_lf_group@blacksheep.org Subject: LF: RE: Coil Huts etc. and RF burns Date: Mon, 15 Jan 2001 12:55:03 -0000 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2650.21) Content-Type: text/plain; charset=iso-8859-1; format=flowed Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: Last night while transmitting BPSK for 15 minute intervals every half hour well into the night, I was making use of the opportunity to get on with the shack rebuilding. My radio room is an upstairs bedroom and the LF antenna top loading wires pass directly above, attached to the apex of the roof probably 3-4m above the shack ceiling. While transmitting, every time I brushed against a piece of earthed metal I could feel a slight RF burn or shock, not detectable if the metal was grabbed but unpleasent if touched gently with an arm or similar. The weather was extremally dry and the antenna load resistance the lowest it has been for some time, which may be why I have not seen this before with the new 600 W amplifier. The field is probably in the region of 2 - 3 kV/m here. Occasionally the fluorescent tube on the ceiling will light faintly with the RF - this was much more noticeable and spectacular on an older fitting that was not on an earthed metal box but left the tube in free space connected to its starter remotely - on 73kHz that would flash brightly with CW keying to the extent that I had to leave the light on when beaconing at night !! So, if you are sitting in the fields generated by 1kW transmitters be prepared for a few minor burns / shocks. And don't ever touch the hot antenna feed, I guess that would give a third degree burn if the arc is maintained for more than a few seconds To once demonstrate the plasma arc, I struck one from a (well insulated) screwdriver and managed to draw it out to 50mm, burning the PTFE wire insulation and marking the screwdriver tip - and that was only on 150W of 73kHz ! Plasm arc welders work like this. Andy G4JNT -- The Information contained in this E-Mail and any subsequent correspondence is private and is intended solely for the intended recipient(s). For those other than the recipient any disclosure, copying, distribution, or any action taken or omitted to be taken in reliance on such information is prohibited and may be unlawful.