Return-Path: Received: from mtain-me06.r1000.mx.aol.com (mtain-me06.r1000.mx.aol.com [172.29.96.142]) by air-db04.mail.aol.com (v129.4) with ESMTP id MAILINDB043-86464be932eb18a; Tue, 11 May 2010 06:35:23 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-me06.r1000.mx.aol.com (Internet Inbound) with ESMTP id EE477380000ED; Tue, 11 May 2010 06:35:21 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OBmmy-00005o-H8 for rs_out_1@blacksheep.org; Tue, 11 May 2010 11:34:12 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OBmmy-00005f-2I for rsgb_lf_group@blacksheep.org; Tue, 11 May 2010 11:34:12 +0100 Received: from fmmailgate04.web.de ([217.72.192.242]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1OBmmv-00012L-Uc for rsgb_lf_group@blacksheep.org; Tue, 11 May 2010 11:34:12 +0100 Received: from mwmweb078 ( [172.20.18.96]) by fmmailgate04.web.de (Postfix) with ESMTP id 49A8F65FFD39 for ; Tue, 11 May 2010 12:29:41 +0200 (CEST) Received: from [84.63.114.217] by mwmweb078 with HTTP; Tue May 11 12:29:41 CEST 2010 MIME-Version: 1.0 Date: Tue, 11 May 2010 12:29:41 +0200 (CEST) Message-ID: <20327716.18234.1273573781296.JavaMail.fmail@mwmweb078> From: =?ISO-8859-15?Q?Horst_St=F6cker?= To: rsgb_lf_group@blacksheep.org X-UI-Message-Type: mail In-Reply-To: References: X-Priority: 3 Importance: normal Sensitivity: Normal X-Provags-ID: V01U2FsdGVkX19ZxehtdEF5S10D99tDtLYdq29jeSHaQchU5dSogv7vbZObgpSMi44p guTHBzH/JuH01jXNcs0Hdtf5TWuUbpMLL4GwqbBFY5pGoShk8VPnoA== X-Spam-Score: 0.7 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,HTML_MIME_NO_HTML_TAG=0.512,MIME_HTML_ONLY=0.001,MPART_ALT_DIFF=0.137 Subject: Re: LF: Sub-9kHz walkabout tests Content-Type: multipart/mixed; boundary=0016e6d99d00ef191e04864ead9f X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: *** X-Spam-Status: No, hits=3.1 required=5.0 tests=HTML_20_30,HTML_MESSAGE, HTML_MIME_NO_HTML_TAG,MIME_HTML_ONLY,PRIORITY_NO_NAME 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-sid: 3039ac1d608e4be932e943c3 X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) --0016e6d99d00ef191e04864ead9f Content-Type: multipart/alternative; boundary=0016e6d99d00ef191504864ead9d --0016e6d99d00ef191504864ead9d Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-UI-ATTACHMENT-ID-POSTFIX: e7e789a6-1765-4f89-b15c-e2e0e6a7ec5e Hello Roger,
this may work in the flat field. Here in the city= a 30m earth base worked worse than my unmatched 10h/20t T-Antenna. With= this the signal was audible in 100 to 200 m (about 300W at 8,9kHz, Receiv= er; homebrew Aatis 69 based portabel VLF-Receiver for natural radio with= whip antenna).
As I told before I am planning a test in the flat fie= ld with an 800 to 1000 m earth base within the next weeks.
I am also= interested in what is possible in this band at my home QTH. I also feel= it's much fun.
I am not familiar to WSPR. Can one bring the audio to= our frequency range just with the soundcard without a linear transverter?= The only mode I am relatively sure about this feture is the widely unknow= n mode CHIP. Unfortunately the best S/R ratio one will still get with QRSS= .
vy73 Horst DO1KHS/DI2AN

Von: Roger Lapthorn <rogerlapthorn@gmail.com>
Gesende= t: 11.05.2010 12:06:30
An: rsgb_lf_group@blacksheep.orgBetreff: LF: Sub-9kHz walkabout tests

This week I've= restarted tests using 3-4W into my 10m spaced grounded electrodes at 1-9k= Hz.

On receive I'm using an 80cm loop into a Sallen-Key active= HPF followed by 3 stages of audio gain into a crystal earpiece. With the= TX sending 1 second 1kHz beeps, I went out into the fields behind my hous= e on the edge of the village to see how far I could receive the signal. Th= e signal was still audible at 0.35kms in several different directions, but= the limit was set by MW/LW broadcast breakthrough and mains hum, so with= a bit of attention I'm sure further is possible. The next test today is= using a VLF up-converter (see my website) feeding into the FT817. Selecti= vity, mains hum and BC rejection should be much better. An attempt at a MO= SFET based up-converter design yesterday failed, I think as the LO signal= was causing blocking or other desensitisation.

I'm intrigued= by what mode the signal is propagating: the loop orientation for best rec= eption clearly indicates induction, so I guess the TX end grounded electro= des and the feed wire (about 1-2m in the air) form a loop in the ground.= The signals at this range are stronger than when I tried some years ago= using grounded electrode pairs at the RX end too. Putting the loop on the= ground, for example, made signals weaker. The tests were carried out in= a mix of directions and there is no evidence that cables and pipework wer= e aiding range. I should try a proper loop at the TX end I guess.
It will be interesting to see if range is greater today with the FT817= and upconverter. Also I'll try at 1kHz, 5kHz and 8.7kHz to see if there= is any noticeable difference. If successful, I want to try WSPR and QRSS= to see how these perform. The range achieved so far was "by ear" listenin= g for a clearly audible beep in the earphone.

This is hardly th= e great DX achieved by Stefan, but fun nonetheless to experiment with ...a= nd no big kite antennas needed!

73s
Roger G3XBM
= ;

--
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/g3xbm
G3XBM &nb= sp; GQRP 1678 ISWL G11088

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dauerhaft kostenlos! Jetzt freischalten= unter http://movieflat.web.de

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