Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by klubnl.pl (8.14.4/8.14.4/Debian-8+deb8u2) with ESMTP id x37CPJei030524 for ; Sun, 7 Apr 2019 14:25:21 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1hD6mg-0001ZJ-HL for rs_out_1@blacksheep.org; Sun, 07 Apr 2019 13:20:26 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1hD6mf-0001ZA-Qy for rsgb_lf_group@blacksheep.org; Sun, 07 Apr 2019 13:20:25 +0100 Received: from mail-wr1-x432.google.com ([2a00:1450:4864:20::432]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.92) (envelope-from ) id 1hD6md-0002DG-R8 for rsgb_lf_group@blacksheep.org; Sun, 07 Apr 2019 13:20:24 +0100 Received: by mail-wr1-x432.google.com with SMTP id j9so13057987wrn.6 for ; Sun, 07 Apr 2019 05:20:22 -0700 (PDT) X-DKIM-Result: Domain=gmail.com Result=Good and Known Domain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:mime-version:subject:date:references:to:in-reply-to:message-id; bh=z16VZLPmzRZCR6GZrBgQ8gFK2Aqcc8XPis00YJj+RGI=; b=KI0H/vbBeEwRCnPtcUI3pH5XUGl9NnOOOPQtXrxLstUU2n5rx1ZISOAVpdtsJIiKh0 8hwOkMrul+wwRfhlbrUvEqRCu5/6nG4mgbUl5PmhZCaz8OwM6oA3Endcn5soieNvPTQv N50MFsaynkcD8AcbTNDtWQHVnc88mz8X8fUP2Iath6xhbG+D9/nk3pwY/iFtY8EQGarS mJPfVOoCFaKtlWs6Pb0SacI5VggVIvecH3cbP48M0e+EJeE3LV4sFOpx+iZu3OJA0U6t eeONG4G4qRKych5ASFnQlqxjHfHsUgTaQ6XbA6Gd7E7yv+NWAtI2xxhJswwz3tEp0B2A 7cMg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:mime-version:subject:date:references:to :in-reply-to:message-id; bh=z16VZLPmzRZCR6GZrBgQ8gFK2Aqcc8XPis00YJj+RGI=; b=Z6H2Opbs1fKgmGOkVCiY3GjcrvvC+c9FuVLyy0zxU79eWtNCIbIeGRdps3Xf2K0tSw YfU7aINN8BHbtGZNoWkWLKom+lUqaSSfx1+HNA49y03n1Eq32BGYclYs7mRm9sLQGW7R 8dyEhQsmm4BV3y40hl3F2yM1q+tn9grlp3h4YvTbEJLTCyfnBlpDsYQiRN97c9OP0sy/ HcwgBr4nDVv5q6MwLeD1rW9lCJ42LnqCBcT+9SC7P67e3L0uLHkN8psGPwc6Q/x+UK9e auVyOyxRzieqzu4JLkfuuTcUIinCZoUkSN2wG4iRGEtufCbpUFjo6r3VO80y4YKxW9gO QBdA== X-Gm-Message-State: APjAAAVhiGk1neuDM843Le6xwNP9rPdsCMIvJ2G6Mws1t5xUvXoNW1uW ujvlKo1GjQvX8+1YyIySMGI5/EeiAzY= X-Google-Smtp-Source: APXvYqzpIc9keyUmy9nqN9waY55y/aAXRqICzR6z0tA6a4Imjin3nnRkkecS51V6mcwbWmjHk8sqRQ== X-Received: by 2002:a5d:69c2:: with SMTP id s2mr14554267wrw.83.1554639621237; Sun, 07 Apr 2019 05:20:21 -0700 (PDT) Received: from [192.168.0.101] ([109.94.33.138]) by smtp.gmail.com with ESMTPSA id z7sm20570869wrt.10.2019.04.07.05.20.20 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 07 Apr 2019 05:20:20 -0700 (PDT) From: John Rabson Mime-Version: 1.0 (Mac OS X Mail 12.4 \(3445.104.8\)) Date: Sun, 7 Apr 2019 14:20:15 +0200 References: <1652663722.1033558.1554575549616.ref@mail.yahoo.com> <1652663722.1033558.1554575549616@mail.yahoo.com> <5CA90E98.2070707@posteo.de> <8c46744b-f60a-ca91-f60f-97a2f5f7b11f@abelian.org> <5CA931D4.6050908@posteo.de> <83eece37-ae11-b2fd-917c-ad29c350695b@abelian.org> <5CA9BD98.2030002@posteo.de> To: rsgb_lf_group@blacksheep.org In-Reply-To: Message-Id: <4A9A54DE-1A4D-48A8-A360-5755FB92A9C4@gmail.com> X-Mailer: Apple Mail (2.3445.104.8) X-Spam-Score: 0.3 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Cave-to-surface communications makes extensive use of earth current systems and these have been a recurrent theme in the Cave Radio & Group Journal (ISSN 1361-4800). See for example issue 55 (March 2004) http://bcra.org.uk/creg/index.html: Content analysis details: (0.3 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [2a00:1450:4864:20:0:0:0:432 listed in] [list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (john.rabson07[at]gmail.com) 0.2 FREEMAIL_ENVFROM_END_DIGIT Envelope-from freemail username ends in digit (john.rabson07[at]gmail.com) 0.0 HTML_MESSAGE BODY: HTML included in message X-Scan-Signature: c8ff00257edaad8e124ab9389da9609a Content-Type: multipart/alternative; boundary="Apple-Mail=_1F9A0811-0F77-4AE7-838C-B075CED1D830" Subject: Re: ULF: EbNaut message transmitted from ground loop X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.3 required=5.0 tests=FROM_ENDS_IN_NUMS,HTML_20_30, 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 --Apple-Mail=_1F9A0811-0F77-4AE7-838C-B075CED1D830 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii Cave-to-surface communications makes extensive use of earth current = systems and these have been a recurrent theme in the Cave Radio & Group = Journal (ISSN 1361-4800). See for example issue 55 (March 2004) = http://bcra.org.uk/creg/index.html:=20 An Earth-Current-Based Cave Intruder Alarm John W. Newman and his wife Jane own a cave in Kentucky, USA, which is = home to an endangered species of grey bat (myotis grisescens). As = warning notices were insufficient to keep out intruders, an electronic = alarm system was devised. =20 Nothing New Underground - WW1 Trench Communications Cave radio, like trench communications in WW1, depends on the = propagation of electrical signals through the earth, and we still have = things to learn. The diaries of Ernest H Hinrichs (US Signal Corps = 1917-1919) are reviewed by John Rabson. 73 John F5VLF > On 7 Apr 2019, at 12:49, Jacek Lipkowski wrote: >=20 > On Sun, 7 Apr 2019, DK7FC wrote: >=20 >> An OM (OT!) of my radio club told stories of his early radio = experiments. He had a friend in some 100m distance and they lay out a = small hidden wire into they ground between their QTHs, using the earth = as the back 'wire'. >=20 > Some electricity (i think they didn't call it electronics back then) = hobby books for boys in the USA has descriptions of using ground dipoles = for telegraphy. The transmitter was a buzzer-like circuit with step-up = transformer, and the receiver was just high impedance headphones. = Unfortunately i don't have the book, but i remember it also showed how = to make a rhumkorff generator from a ford t ignition coil, so it must = have been very old. >=20 >=20 > I also remember reading somewhere that during the war (not sure it was = WW II) using amateur radio equipment was prohibited, and the ARRL = advised using similar equipment, so that people don't loose their = operating skills. >=20 > No doubt some people used much larger ground dipoles than advised in = the books :) >=20 > VY 73 >=20 > Jacek / SQ5BPF >=20 >=20 --Apple-Mail=_1F9A0811-0F77-4AE7-838C-B075CED1D830 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=us-ascii Cave-to-surface communications makes extensive use of earth = current systems and these have been a recurrent theme in the Cave Radio = & Group Journal (ISSN 1361-4800).

See for example issue 55 (March = 2004) http://bcra.org.uk/creg/index.html: 

An = Earth-Current-Based Cave Intruder Alarm
John W. Newman and his wife Jane own a cave in Kentucky, = USA, which is home to an endangered species of grey bat (myotis = grisescens). As warning notices were insufficient to keep out intruders, = an electronic alarm system was devised.
 
Nothing New Underground - WW1 Trench = Communications
Cave radio, like = trench communications in WW1, depends on the propagation of electrical = signals through the earth, and we still have things to learn. The = diaries of Ernest H Hinrichs (US Signal Corps 1917-1919) are reviewed by = John Rabson.

73 John = F5VLF

On 7 Apr 2019, at 12:49, Jacek Lipkowski <sq5bpf@lipkowski.org> wrote:

On = Sun, 7 Apr 2019, DK7FC wrote:

An OM (OT!) of my radio club told stories of = his early radio experiments. He had a friend in some 100m distance and = they lay out a small hidden wire into they ground between their QTHs, = using the earth as the back 'wire'.

Some electricity (i think they didn't call it electronics = back then) hobby books for boys in the USA has descriptions of using = ground dipoles for telegraphy. The transmitter was a buzzer-like circuit = with step-up transformer, and the receiver was just high impedance = headphones. Unfortunately i don't have the book, but i remember it also = showed how to make a rhumkorff generator from a ford t ignition coil, so = it must have been very old.


I = also remember reading somewhere that during the war (not sure it was WW = II) using amateur radio equipment was prohibited, and the ARRL advised = using similar equipment, so that people don't loose their operating = skills.

No doubt some people used much = larger ground dipoles than advised in the books :)

VY 73

Jacek / SQ5BPF



= --Apple-Mail=_1F9A0811-0F77-4AE7-838C-B075CED1D830--