Return-Path: Received: from mtain-ma02.r1000.mx.aol.com (mtain-ma02.r1000.mx.aol.com [172.29.96.10]) by air-mc08.mail.aol.com (v127_r1.1) with ESMTP id MAILINMC083-a98d4b9573051a8; Mon, 08 Mar 2010 16:58:29 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-ma02.r1000.mx.aol.com (Internet Inbound) with ESMTP id E431038000116; Mon, 8 Mar 2010 16:58:27 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NokxN-00026A-QS for rs_out_1@blacksheep.org; Mon, 08 Mar 2010 21:57:45 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NokxN-000260-8M for rsgb_lf_group@blacksheep.org; Mon, 08 Mar 2010 21:57:45 +0000 Received: from mail-bw0-f215.google.com ([209.85.218.215]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1NokxK-0005jc-IV for rsgb_lf_group@blacksheep.org; Mon, 08 Mar 2010 21:57:45 +0000 Received: by bwz7 with SMTP id 7so4925906bwz.4 for ; Mon, 08 Mar 2010 13:57:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:content-type; bh=oqBch80QVFyFJ4xL5xDJi/CV3opvdMvBh96ipASpknY=; b=XefIXiRUZ5jCJCbgMBCeoBUYT/y4UPk36ZzfTcIEFSwuz7UXZDGoluW0o2CxZSmamH sNinQ+ptkM1VtQ4uY0i3PMswiAuUOrmbCdZk/wm5U9USm0z3x8mWqsPLT6JAndnB7oqN b4PAfsfrEoVFHTOFpaU+Snty3fkNshdA+KcwE= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=lQxpEVgeqAqzklLgokCX1Z6VqesKsICx4qPvUXsuM/hO50MOFH+4i8DrLLcTW9+kXx ktEERUWDw4bbyMUbOGts6yob0MBFpeyhYmcpLpqMZsfJeOzXnIA4pyJL9sxxnugIOwzL QbwNVdsg7SRb42yMzBCMN8oqWopM/cAY+8eUE= MIME-Version: 1.0 Received: by 10.204.9.134 with SMTP id l6mr5970695bkl.83.1268085455795; Mon, 08 Mar 2010 13:57:35 -0800 (PST) In-Reply-To: References: Date: Mon, 8 Mar 2010 21:57:35 +0000 Message-ID: <9afca2641003081357l2a4e6b35oa775312dea007510@mail.gmail.com> From: Roger Lapthorn To: rsgb_lf_group@blacksheep.org DomainKey-Status: good (testing) X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: VLF Content-Type: multipart/alternative; boundary=00151758b1842337a20481512746 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: 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-aol-global-disposition: G X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-m205.1 ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1d600a4b9573034418 X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) --00151758b1842337a20481512746 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Andy et al, I tried this when I last experimented with "earth mode" conduction at 1kHz some 20 years ago. I used the central heating ground and a meat skewer at the far end some 10m away from the house. I was able to copy the keyed signal by ear some 300m away with minimal filtering on a second grounded electrode pair of meat skewers! I made no attempt to elevate the loop at either end. I could adjust the resistive match from 20 ohms to 150 ohms at the TX end but cannot remember the settings I used. I made no attempt to tune out any reactive part. The signal was also copied some 200m away in= the middle of a field well away from wires,pipes and cables with a 5m base lin= e and meat skewer grounds. Power was around 4W out from a small TDA2002 audi= o chip. This leads me to think that much further would be possible by "earth mode" with more power, larger base line spacing, elevated wire and QRSS. All good fun. 73s Roger G3XBM On 8 March 2010 18:42, Andy Talbot wrote: > ...wishing I'd persued the NoV application a few years ago instead of ju= st > letting it slide into oblivion... > > Has anyone yet tried a ground loop at 9kHz? That was going to be my fi= rst > (and probably only) antenna type, running a length of wire as far away= from > the house as I could get-away with and connecting it to a ground stake,= then > feeding this against the existing local earth. I never got round to ma= king > measurements to see what sort of ground resistance might be > expected, but that would have been a lot easier than winding 1.4H air wo= und > chokes. > > My house backs onto a main road, and there is a drainage ditch running > behide trees and foliage running for about 70m in one direction that wou= ld > have made a useful route to hide a wire in. Might have been interesting > hammering in a ground stake next to the footpath at the corner of the > next road though ! > > Andy > www.g4jnt.com > > > 2010/3/8 Wolfgang B=FCscher > >> Hi Stefan, >> >> >> A VLF grabber would be very fine! If you can arrange that, it would >>> perhaps be a motivation for the dreamers ;-) >>> >>> >> Well there are two now (Markus' and Paul's) .. I will try to add a thir= d >> but need to get away from the local QRM. The plan is to use an UHF FM= link >> to the remote, battery-powered site but there are some issues to be sol= ved - >> one of them is the lack of dynamic range of the FM transmitter/receiver= , so >> I may have to add some analog bandpass filtering before the FM modulato= r >> (which would render it useless for broadband VLF signals, especially na= tural >> radio signals..). >> >> Will keep you informed, when/where another VLF 'live spectrogram' goes >> online. >> >> Cheers, >> Wolf . >> >> >> > --=20 http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/G3XBM G3XBM GQRP 1678 ISWL G11088 --00151758b1842337a20481512746 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Andy et al,

I tried this when I last experimented with "earth= mode" conduction at 1kHz some 20 years ago. I used the central heati= ng ground and a meat skewer at the far end some 10m away from the house.= I was able to copy the keyed signal by ear some 300m away with minimal fi= ltering on a second grounded electrode pair of meat skewers! I made no att= empt to elevate the loop at either end. I could adjust the resistive match= from 20 ohms to 150 ohms at the TX end but cannot remember the settings= I used. I made no attempt to tune out any reactive part. The signal was= also copied some 200m away in the middle of a field well away from wires,= pipes and cables with a 5m base line and meat skewer grounds. Power was ar= ound 4W out from a small TDA2002 audio chip. This leads me to think that= much further would be possible by "earth mode" with more power,= larger base line spacing, elevated wire and QRSS.

All good fun.

73s
Roger G3XBM



On 8 March 2010 18:42, Andy Talbot <andy.g4jnt@googlemail.com><= /span> wrote:
...wishing= I'd persued=A0the NoV application a few years ago instead of just let= ting it slide into oblivion...
=A0
Has anyone yet tried a ground loop at 9kHz?=A0=A0 That was going to= be my first (and probably only) antenna type, running a length of wire as= far away from the house as I could get-away with and connecting it to a= ground stake, then feeding this against the existing local earth.=A0=A0= I never got round to=A0making measurements to see what sort of ground res= istance might be expected,=A0but=A0that would have been a lot easier than= winding 1.4H air wound chokes.
=A0
My house backs onto a main road, and there is a drainage ditch runnin= g behide trees and foliage running for about 70m in one direction that wou= ld have made a useful route to=A0hide=A0a wire in.=A0 Might have been inte= resting hammering in a ground stake=A0next to the footpath at the corner= of the next=A0road though !
2010/3/8 Wolfgang B=FCscher &= lt;dl4yhf@freenet.d= e>
Hi Stefan,
<= br>
A VLF grabber= would be very fine! If you can arrange that, it would perhaps be a motiva= tion for the dreamers ;-)
=A0
Well there are two now (Markus' and Paul's) ..= I will try to add a third but need to get away from the local QRM. The pl= an is to use an UHF FM link to the remote, battery-powered site but there= are some issues to be solved - one of them is the lack of dynamic range= of the FM transmitter/receiver, so I may have to add some analog bandpass= filtering before the FM modulator (which would render it useless for broa= dband VLF signals, especially natural radio signals..).

Will keep you informed, when/where another VLF 'live spectrogram&#= 39; goes online.

Cheers,
=A0Wolf .






--

http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/G3XBM
G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL G11088
--00151758b1842337a20481512746--