Return-Path: Received: (qmail 93311 invoked from network); 10 Mar 2005 18:24:46 -0000 Received: from unknown (HELO ptb-spamcore01.plus.net) (192.168.71.1) by ptb-mailstore02.plus.net with SMTP; 10 Mar 2005 18:24:46 -0000 Received: from mailnull by ptb-spamcore01.plus.net with spamcore-l-b (Exim 4.32; FreeBSD) id 1D9SNr-0008Hi-ON for dave@picks.force9.co.uk; Thu, 10 Mar 2005 18:27:44 +0000 Received: from [192.168.67.1] (helo=ptb-mxcore01.plus.net) by ptb-spamcore01.plus.net with esmtp (Exim 4.32; FreeBSD) id 1D9SNr-0008HU-2m for dave@picks.force9.co.uk; Thu, 10 Mar 2005 18:27:43 +0000 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore01.plus.net with esmtp (Exim) id 1D9SNX-0004gO-2S for dave@picks.force9.co.uk; Thu, 10 Mar 2005 18:27:23 +0000 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1D9SKQ-0000VX-MR for rs_out_1@blacksheep.org; Thu, 10 Mar 2005 18:24:10 +0000 Received: from [193.82.116.30] (helo=relay.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1D9SKQ-0000VO-6W for rsgb_lf_group@blacksheep.org; Thu, 10 Mar 2005 18:24:10 +0000 Received: from cas-mta1-fe.casema.nl ([83.80.1.20] helo=mta.casema.nl) by relay.thorcom.net with esmtp (Exim 4.43) id 1D9SKO-0007Jp-Or for rsgb_lf_group@blacksheep.org; Thu, 10 Mar 2005 18:24:10 +0000 Received: from s9z5i6.casema.nl ([83.85.106.243]) by cas-mta1.mgmt.casema.nl (Sun Java System Messaging Server 6.1 HotFix 0.11 (built Jan 28 2005)) with ESMTP id <0ID50027GF3ZWU30@cas-mta1.mgmt.casema.nl> for rsgb_lf_group@blacksheep.org; Thu, 10 Mar 2005 19:24:03 +0100 (CET) Date: Thu, 10 Mar 2005 19:25:49 +0100 From: Dick Rollema X-Sender: dickrollema@casema.nl@mail.casema.nl (Unverified) To: LF-Group Message-id: <6.1.0.6.2.20050310191314.02805c70@mail.casema.nl> MIME-version: 1.0 X-Mailer: QUALCOMM Windows Eudora Version 6.1.0.6 X-SPF-Result: relay.thorcom.net: 83.80.1.20 is neither permitted nor denied by domain of casema.nl X-Spam-Score: 0.3 (/) X-Spam-Report: autolearn=no,FORGED_RCVD_HELO=0.05,HTML_10_20=0.295,HTML_MESSAGE=0.001 Subject: LF: Off topic Content-type: text/html; charset=windows-1252 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Status: No, hits=0.0 required=5.0 tests=HTML_MESSAGE autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-Spam-Filtered: by PlusNet SpamCORE (v3.00) Content-transfer-encoding: 8bit TYo All from PA0SE

I am presently writing an article for our VERON magazine Electron on the early radio experiments by Marconi. In these experiments spark gaps played an important role. Because I would like to perform some simple calculations on the peak power radiated by a spark transmitter I am looking for data on the break down voltage of spark gaps, consisting of two spheres.
In literature, found on the Internet, 75kV/inch is quoted but it is not stated whether this is between points or spheres and that makes a lot of difference.
Temperature and air pressure also influence break down voltage but I will forget about that, reckoning with "normal" conditions of,
say , 20 degrees centigrade and 1000 hectopascal or whatever as reckoned as standard barometric pressure.
Your help will be very much appreciated.

73, Dick, PA0SE
JN22GD