Return-Path: Received: (qmail 30457 invoked from network); 13 Mar 2005 13:22:50 -0000 Received: from unknown (HELO ptb-spamcore01.plus.net) (192.168.71.1) by ptb-mailstore03.plus.net with SMTP; 13 Mar 2005 13:22:50 -0000 Received: from mailnull by ptb-spamcore01.plus.net with spamcore-l-b (Exim 4.32; FreeBSD) id 1DAT6a-000G6N-4W for dave@picks.force9.co.uk; Sun, 13 Mar 2005 13:26:06 +0000 Received: from [192.168.67.2] (helo=ptb-mxcore02.plus.net) by ptb-spamcore01.plus.net with esmtp (Exim 4.32; FreeBSD) id 1DAT6W-000G4G-41 for dave@picks.force9.co.uk; Sun, 13 Mar 2005 13:26:00 +0000 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore02.plus.net with esmtp (Exim) id 1DAT3F-000EDp-5f for dave@picks.force9.co.uk; Sun, 13 Mar 2005 13:22:37 +0000 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1DAT2e-0000Mi-Qo for rs_out_1@blacksheep.org; Sun, 13 Mar 2005 13:22:00 +0000 Received: from [193.82.116.30] (helo=relay.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1DAT2e-0000MZ-43 for rsgb_lf_group@blacksheep.org; Sun, 13 Mar 2005 13:22:00 +0000 Received: from cas-mta4-fe.casema.nl ([83.80.1.32] helo=mta.casema.nl) by relay.thorcom.net with esmtp (Exim 4.43) id 1DAT2b-0006wT-JU for rsgb_lf_group@blacksheep.org; Sun, 13 Mar 2005 13:22:00 +0000 Received: from s9z5i6.casema.nl ([83.85.106.243]) by cas-mta4.mgmt.casema.nl (Sun Java System Messaging Server 6.1 HotFix 0.11 (built Jan 28 2005)) with ESMTP id <0IDA000HHL46UD50@cas-mta4.mgmt.casema.nl> for rsgb_lf_group@blacksheep.org; Sun, 13 Mar 2005 14:21:50 +0100 (CET) Date: Sun, 13 Mar 2005 13:31:25 +0100 From: Dick Rollema In-reply-to: <20050310194826.99075.qmail@web25704.mail.ukl.yahoo.com> X-Sender: dickrollema@casema.nl@mail.casema.nl (Unverified) To: rsgb_lf_group@blacksheep.org Message-id: <6.1.0.6.2.20050313132831.03542ea0@mail.casema.nl> MIME-version: 1.0 X-Mailer: QUALCOMM Windows Eudora Version 6.1.0.6 References: <6667@casema.nl> <20050310194826.99075.qmail@web25704.mail.ukl.yahoo.com> X-SPF-Result: relay.thorcom.net: 83.80.1.32 is neither permitted nor denied by domain of casema.nl X-Spam-Score: 0.6 (/) X-Spam-Report: autolearn=no,FORGED_RCVD_HELO=0.05,HTML_20_30=0.504,HTML_MESSAGE=0.001 Subject: Re: 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 Dear Brian,

Thanks for your reply. I also possess Reference Data for Radio Engineers. I found the info you proviided on page 921. This is what I was looking for!

73, Dick, PA0SE

At 20:48 10-3-05, you wrote:

Hi Dick

Looking in my trusty "Reference Data for Radio Engineers" (won in a rally raffle at least 40 years ago !) the spark gap voltages chart indicates about 30 kV per inch for "needles" and between 55 and 80 kV for spheres spaced and inch apart (depending on the size of the spheres). Hope that helps.

Brian

Dick Rollema <dickrollema@casema.nl> wrote:

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

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