Envelope-to: dave@picks.force9.co.uk Delivery-date: Mon, 01 Aug 2005 13:50:31 +0100 Received: by pih-mxcore18.plus.net with spam-scanned (PlusNet MXCore v2.00) id 1DzZkV-0003uP-7h for dave@picks.force9.co.uk; Mon, 01 Aug 2005 13:50:31 +0100 Received: from post.thorcom.com ([193.82.116.20]) by pih-mxcore18.plus.net with esmtp (PlusNet MXCore v2.00) id 1DzZkV-0003uE-3r for dave@picks.force9.co.uk; Mon, 01 Aug 2005 13:50:31 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1DzZkK-0000MJ-D7 for rs_out_1@blacksheep.org; Mon, 01 Aug 2005 13:50:20 +0100 Received: from [193.82.59.130] (helo=relay2.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1DzZkJ-0000MA-Sj for rsgb_lf_group@blacksheep.org; Mon, 01 Aug 2005 13:50:19 +0100 Received: from cas-mta3-fe.casema.nl ([83.80.1.28] helo=mta.casema.nl) by relay2.thorcom.net with esmtp (Exim 4.51) id 1Dza4F-00065h-AI for rsgb_lf_group@blacksheep.org; Mon, 01 Aug 2005 14:11:01 +0100 Received: from s9z5i6.casema.nl ([83.85.106.243]) by cas-mta3.mgmt.casema.nl (Sun Java System Messaging Server 6.1 HotFix 0.11 (built Jan 28 2005)) with ESMTP id <0IKJ009KCNNG7860@cas-mta3.mgmt.casema.nl> for rsgb_lf_group@blacksheep.org; Mon, 01 Aug 2005 14:50:06 +0200 (CEST) Date: Mon, 01 Aug 2005 14:50:04 +0200 From: Dick Rollema In-reply-to: <005301c59688$9fa05250$6405a8c0@MJUSonyLaptop> X-Sender: dickrollema@casema.nl@mail.casema.nl (Unverified) To: rsgb_lf_group@blacksheep.org Message-id: <6.1.0.6.2.20050801141446.07a2feb0@mail.casema.nl> MIME-version: 1.0 X-Mailer: QUALCOMM Windows Eudora Version 6.1.0.6 References: <003301c5967e$422fc600$0600a8c0@router> <005301c59688$9fa05250$6405a8c0@MJUSonyLaptop> Subject: Re: LF: RE: Soil Conductivity Measurement Content-type: text/html; charset=windows-1252 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-PN-SpamFiltered: by PlusNet MXCore (v2.00) Content-transfer-encoding: 8bit To All from PA0SE

Mike, G3LHZ, wrote:

Has anyone on the list experience in measuring ground conductivity at such frequencies?

I do it by first resonating the aerial system at 137kHz. Then I measure the total resistance of the aerial-earth system by connecting a measuring bridge between the bottom end of the coil and earth. The bridge can be a simple one because it only has to measure a pure resistance. Loss resistance of the coil can be found from its inductance and Q. Subtracting this from the total resistance yields the earth resistance. Radiation resistance and loss resistance of the aerial itself are negligible contributions to the total.

It is indeed important to measure the resistance at the actual working frequency as it is frequency dependent. See ON7YD's website
http://www.qsl.net/on7yd/136khz.htm.

In my station the only earth electrode is the gas mains. Earth resistance varies with season and humidity of the ground but usually is of the order of 22 ohms or so. But we live in a polder almost with our feet in the water.

73, Dick, PA0SE