Return-Path: Received: (qmail 21878 invoked from network); 10 Mar 2005 19:53:51 -0000 Received: from unknown (HELO ptb-spamcore01.plus.net) (192.168.71.1) by ptb-mailstore01.plus.net with SMTP; 10 Mar 2005 19:53:51 -0000 Received: from mailnull by ptb-spamcore01.plus.net with spamcore-l-b (Exim 4.32; FreeBSD) id 1D9Tm5-000BkU-IV for dave@picks.force9.co.uk; Thu, 10 Mar 2005 19:56:50 +0000 Received: from [192.168.67.1] (helo=ptb-mxcore01.plus.net) by ptb-spamcore01.plus.net with esmtp (Exim 4.32; FreeBSD) id 1D9Tm5-000BkR-Fn for dave@picks.force9.co.uk; Thu, 10 Mar 2005 19:56:49 +0000 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore01.plus.net with esmtp (Exim) id 1D9Tll-0003Ze-3M for dave@picks.force9.co.uk; Thu, 10 Mar 2005 19:56:29 +0000 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1D9Tj2-0000ob-Rr for rs_out_1@blacksheep.org; Thu, 10 Mar 2005 19:53:40 +0000 Received: from [193.82.116.30] (helo=relay.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1D9Tj2-0000oS-EB for rsgb_lf_group@blacksheep.org; Thu, 10 Mar 2005 19:53:40 +0000 Received: from mailout02.sul.t-online.com ([194.25.134.17]) by relay.thorcom.net with esmtp (Exim 4.43) id 1D9Tj0-0007cW-Vm for rsgb_lf_group@blacksheep.org; Thu, 10 Mar 2005 19:53:40 +0000 Received: from fwd35.aul.t-online.de by mailout02.sul.t-online.com with smtp id 1D9Tj0-0002kP-00; Thu, 10 Mar 2005 20:53:38 +0100 Received: from oben (Xd8FksZLZeSe7u7HIoXzCa5S7A2d0OrAnBN-ZGqVM4wpQY8EJW3gZQ@[84.178.221.46]) by fwd35.sul.t-online.de with smtp id 1D9Tir-06FRuS0; Thu, 10 Mar 2005 20:53:29 +0100 Message-ID: <000b01c525ad$23408cd0$ee9bfea9@oben> From: "dj9dw" To: rsgb_lf_group@blacksheep.org References: <6.1.0.6.2.20050310191314.02805c70@mail.casema.nl> Date: Thu, 10 Mar 2005 21:09:59 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1437 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1441 X-ID: Xd8FksZLZeSe7u7HIoXzCa5S7A2d0OrAnBN-ZGqVM4wpQY8EJW3gZQ X-TOI-MSGID: 0ba379f2-eb4e-4bcf-9db9-f8c6800f85f3 X-SPF-Result: relay.thorcom.net: 194.25.134.17 is neither permitted nor denied by domain of t-online.de X-Spam-Score: 0.1 (/) X-Spam-Report: autolearn=failed,HTML_40_50=0.086,HTML_MESSAGE=0.001 Subject: LF: Re: 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=0.8 required=5.0 tests=HTML_30_40,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

Hello Dick,

between a peak and a plate it takes 1 kV.

Between two balls ( diameter?) - spheres - abt 3 kV. per mm. Don't ask me for kV/m.

73 Peter, dj9dw.

----- Original Message -----

From: Dick Rollema

To: LF-Group

Sent: Thursday, March 10, 2005 7:25 PM

Subject: LF: Off topic

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