[Lf] [Fwd: LF: Strange signals on 25 Hz (!) - any info ?]

[Andre Kesteloot]

DL4YHF at aol.com wrote:

> 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 !
>
>



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