Return-Path: Received: (qmail 20950 invoked from network); 22 Jun 2002 05:57:58 -0000 Received: from murphys.services.quay.plus.net (212.159.14.225) by mailstore with SMTP; 22 Jun 2002 05:57:58 -0000 Received: (qmail 4703 invoked from network); 22 Jun 2002 05:57:28 -0000 Received: from post.thorcom.com (193.82.116.70) by murphys.services.quay.plus.net with SMTP; 22 Jun 2002 05:57:28 -0000 X-SQ: A Received: from majordom by post.thorcom.com with local (Exim 3.33 #2) id 17LdnC-0004fD-00 for rsgb_lf_group-outgoing@blacksheep.org; Sat, 22 Jun 2002 06:50:38 +0100 Received: from mail2.dada.it ([195.110.96.69] helo=mail.dada.it) by post.thorcom.com with smtp (Exim 3.33 #2) id 17LdnA-0004f8-00 for rsgb_lf_group@blacksheep.org; Sat, 22 Jun 2002 06:50:37 +0100 Received: (qmail 31786 invoked from network); 22 Jun 2002 05:50:02 -0000 Received: from unknown (HELO cestag) (195.110.102.69) by mail.dada.it with SMTP; 22 Jun 2002 05:50:02 -0000 Message-ID: <002601c219b0$7de826e0$45666ec3@cestag> From: "cesare tagliabue" To: rsgb_lf_group@blacksheep.org References: <1ab.3fdfee5.2a44bcd0@aol.com> Subject: LF: R: Strange signals on 25 Hz (!) - any info ? Date: Sat, 22 Jun 2002 07:48:51 +0200 MIME-Version: 1.0 Content-Type: text/html; charset=windows-1252 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.00.2919.6600 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: Content-transfer-encoding: 8bit
    Hello Wolf
        The Signal you receive is like a telephon call, some old systems use a 25 Hz a.c. with one second duration and 4 seconds space. Nevertheless it is very difficult that these signals can reach your receiver. Hope someone has better suggestions,  73  Cesare
 
Cesare Tagliabue   I 5 TGC
WW-Loc  JN53PS
e-mail: cestag@dada.it
url: http://www.dadacasa.com/i5tgc
-----Messaggio Originale-----
Da: DL4YHF@aol.com
A: rsgb_lf_group@blacksheep.org
Data invio: venerd́ 21 giugno 2002 19.30
Oggetto: LF: Strange signals on 25 Hz (!) - any info ?

Hello Group,

Has anyone of this group ever heard about signals in the range of 25 Hz, like this:

- a few pulses of about one second length each, about 4 seconds pause between them
- transmitted irregularly, sometimes not present for days or weeks
- obviously NOT related to the mains line, no harmonics or images at 50 and 75 Hz etc
- seem NOT to travel through the mains line.

The following is quoted from Renato Romero:

>>>Hi Wolf,
about that strange signal at 25 Hz: I receive that signal since 1997, when I started with regular reception below 50Hz thanks a circuit of IK1ODO with OP07 op amplifier and a big T marconi antenna. Those strange dots appear sometimes, not always at the same time, and not always in the same form: sometimes there are one o two dots, sometimes there are 13 dots or more. They disappear for many days, then appear again with a not regular schedule.
About the origin: agree with you about the not natural origin, is clear; but what they really are ... it's a mystery.
They are not inducted by main power lines because they are not present in the reception with a big horizontal loop (30m x 30m, 3 turns), instead of the signals on the electric line at 1024Hz, present on air and very strong in horizontal polarization.
They are not caused by not linear loads on the electric line: that signals appear like a mirror with 50Hz (and 150Hz, 250Hz...): in this case there is no signal at 75 Hz.
<<<

Any ideas ? Another submarine "wakeup" transmitter ?

73, Wolf



P.S. Looking forward to Dick's Feldhell transmission. Will try to answer in that mode, but I few its not really suited for my low-power signal - so possibly will reply in CW.


P.P.S. Walter DJ2LF will hold his LF talk at the Ham Radio fair in Friedrichshaven on Friday June 28, after 16:00 local in hall 2, room "C", after an introduction by DL1VDL. .... at least, this is written in the german CQ DL magazine. They warn about "problems with the parking space" this year and ask visitors to use the shuttle bus. Hope to meet you there !