Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dl03.r1000.mx.aol.com (Internet Inbound) with ESMTP id 8C566380000BC; Wed, 12 Oct 2011 06:19:56 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1RDvtd-0001Uy-6W for rs_out_1@blacksheep.org; Wed, 12 Oct 2011 11:18:45 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1RDvtc-0001Up-Km for rsgb_lf_group@blacksheep.org; Wed, 12 Oct 2011 11:18:44 +0100 Received: from relay.uni-heidelberg.de ([129.206.100.212]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1RDvtb-0005Bx-87 for rsgb_lf_group@blacksheep.org; Wed, 12 Oct 2011 11:18:44 +0100 Received: from freitag.iup.uni-heidelberg.de (freitag.iup.uni-heidelberg.de [129.206.29.204]) by relay.uni-heidelberg.de (8.14.1/8.14.1) with ESMTP id p9CAIfkI001147 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Wed, 12 Oct 2011 12:18:42 +0200 Received: from [129.206.22.206] (pc206.iup.uni-heidelberg.de [129.206.22.206]) by freitag.iup.uni-heidelberg.de (8.12.11.20060308/8.11.2) with ESMTP id p9CAIfoU023227 for ; Wed, 12 Oct 2011 12:18:41 +0200 Message-ID: <4E956953.3030207@iup.uni-heidelberg.de> Date: Wed, 12 Oct 2011 12:17:55 +0200 From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <4E91694C.8060900@orange.fr> <4E9169AD.8090609@wanadoo.fr> <4E918C0E.30401@freenet.de> <4E918FF1.1010407@iup.uni-heidelberg.de> <1318166502.15085.YahooMailNeo@web28106.mail.ukl.yahoo.com> <1849736542-1318171189-cardhu_decombobulator_blackberry.rim.net-208700020-@b1.c11.bise7.blackberry> <4E920BBA.9040200@iup.uni-heidelberg.de> <4E934A40.9040204@gmx.de> <006c01cc87ab$427234c0$4001a8c0@lark> <834DCCD1D3834F4CB4C171B7C30E85B4@AGB> <004801cc8809$63378d50$4001a8c0@lark> , In-Reply-To: X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,RATWARE_GECKO_BUILD=1.426 Subject: Re: LF: VX9MRC QRV 507.77 kHz/ Arcing relays &c. Content-Type: multipart/alternative; boundary="------------070007030909020104050400" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.9 required=5.0 tests=HTML_30_40,HTML_FONTCOLOR_BLUE, 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-aol-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:454462400:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d4ad14e9569cc60e0 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. --------------070007030909020104050400 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Hello Rik, Interesting, haven't known that. What do you think applies for a 10mm diameter wire? 73, Stefan Am 12.10.2011 09:30, schrieb Rik Strobbe: > > /I'm puzzled by the 6pf/metre rule for monoploes. It seems the > capacitance of the monopole is much higher./ > > Hi Joe, > > based on a resonance with 3mH @137.8kHz the antenna capacitance would > be 445pF. > > A rato of 5..6pF/m you should have more or less 75..90m of wire up in > the air (vertical and horizontal section). > > But the given value of 5..6pF/m is only valid for thin wire. If you > use very thick wire or maybe even a tower as part of the antenna the > capacitance is larger. For a 1m diameter tower the capacitance can be > as high as 25pF/m > > 73, Rik ON7YD - OR7T > --------------070007030909020104050400 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Hello Rik,

Interesting, haven't known that. What do you think applies for a 10mm diameter wire?

73, Stefan

Am 12.10.2011 09:30, schrieb Rik Strobbe:

I'm puzzled by the 6pf/metre rule for monoploes.  It seems the capacitance of the monopole is much higher.

 

Hi Joe,

 

based on a resonance with 3mH @137.8kHz the antenna capacitance would be 445pF.

A rato of 5..6pF/m you should have more or less 75..90m of wire up in the air (vertical and horizontal section).

But the given value of 5..6pF/m is only valid for thin wire. If you use very thick wire or maybe even a tower as part of the antenna the capacitance is larger. For a 1m diameter tower the capacitance can be as high as 25pF/m

 

73, Rik  ON7YD - OR7T

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