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Good LF DX Weather? -- Propagation Question

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  • Mark
    Sorry for the newbie question, but what affects long distance LF propagation? Mostly I m interested in 200kHz to 500kHz (NDB DXing), but I m also curious about
    Message 1 of 13 , Nov 2, 2006
      Sorry for the newbie question, but what affects long distance LF
      propagation? Mostly I'm interested in 200kHz to 500kHz (NDB DXing), but
      I'm also curious about down in the VLF region.

      Are there web resources that I could use to check for good LF
      DX "weather"? What parameters would I look at?

      Thanks,
      Mark
    • ny2h
      Hi Mark, Alan Melia maintains a longwave propagation page at: http://www.alan.melia.btinternet.co.uk/latest.htm#Latest%20Propagation%20Report Alan s page is
      Message 2 of 13 , Nov 3, 2006
        Hi Mark,

        Alan Melia maintains a longwave propagation page at:
        http://www.alan.melia.btinternet.co.uk/latest.htm#Latest%20Propagation%20Report

        Alan's page is oriented to the 137 kHz ham band.

        In general this group (VLF_Group Natural Radio VLF Discussion Group)
        is interested in whistlers, tweeks, and other VLF phenomena rather
        than NDB beacons which operate at LF. I believe that there is a group
        for NDB enthusiasts but unfortunately I don't have the URL.

        73 Warren K2ORS/WD2XGJ/WD2XSH/23


        --- In VLF_Group@yahoogroups.com, "Mark" <renderdog7@...> wrote:
        >
        > Sorry for the newbie question, but what affects long distance LF
        > propagation? Mostly I'm interested in 200kHz to 500kHz (NDB DXing), but
        > I'm also curious about down in the VLF region.
        >
        > Are there web resources that I could use to check for good LF
        > DX "weather"? What parameters would I look at?
        >
        > Thanks,
        > Mark
        >
      • Mark
        Thanks Warren, I ll have a look at Alan s page. I knew I was a bit off topic with the LF question ;) Mark ... 20Propagation%20Report ... Group) ... group ...
        Message 3 of 13 , Nov 3, 2006
          Thanks Warren,

          I'll have a look at Alan's page. I knew I was a bit off topic with
          the LF question ;)

          Mark

          --- In VLF_Group@yahoogroups.com, "ny2h" <ny2h@...> wrote:
          >
          > Hi Mark,
          >
          > Alan Melia maintains a longwave propagation page at:
          > http://www.alan.melia.btinternet.co.uk/latest.htm#Latest%
          20Propagation%20Report
          >
          > Alan's page is oriented to the 137 kHz ham band.
          >
          > In general this group (VLF_Group Natural Radio VLF Discussion
          Group)
          > is interested in whistlers, tweeks, and other VLF phenomena rather
          > than NDB beacons which operate at LF. I believe that there is a
          group
          > for NDB enthusiasts but unfortunately I don't have the URL.
          >
          > 73 Warren K2ORS/WD2XGJ/WD2XSH/23
          >
          >
          > --- In VLF_Group@yahoogroups.com, "Mark" <renderdog7@> wrote:
          > >
          > > Sorry for the newbie question, but what affects long distance LF
          > > propagation? Mostly I'm interested in 200kHz to 500kHz (NDB
          DXing), but
          > > I'm also curious about down in the VLF region.
          > >
          > > Are there web resources that I could use to check for good LF
          > > DX "weather"? What parameters would I look at?
          > >
          > > Thanks,
          > > Mark
          > >
          >
        • Renato Romero
          From BBC web site 06 Nov/06: An overload in Germany s power network triggered outages leaving millions without electricity on Saturday night. Here my ELF
          Message 4 of 13 , Nov 6, 2006
            From BBC web site 06 Nov/06:
            "An overload in Germany's power network triggered outages leaving
            millions without electricity on Saturday night."

            Here my ELF monitoring from Cumiana (NW Italy)

            http://www.vlf.it/temp/05NOV06-0000_E.jpg
            Spectrogram by a geophone (up) and electric field (down)

            http://www.vlf.it/temp/05NOV06-0000_H-rdf.jpg
            RDF spectrogram, magnetic component, acquired with two orthogonal minimal loop

            http://www.vlf.it/temp/fault.jpg
            Details of the fault: power network frequency get down to 49 Hz for
            many minutes,

            http://www.vlf.it/temp/fault_timeb.jpg
            Details in the time domain, about 240 mS showed


            73, de ik1qfk
            Renato Romero


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          • thierry alves
            Hello Renato, Thanks for the pictures...Whaouou 50 Hz moved a lot, how can it be ? Thierry. _________________________________________________________________
            Message 5 of 13 , Nov 6, 2006
              Hello Renato,
              Thanks for the pictures...Whaouou 50 Hz moved a lot, how can it be ?

              Thierry.

              _________________________________________________________________
              MSN Hotmail sur i-modeĀ™ : dialoguez avec vos amis depuis votre mobile comme
              sur PC ! http://mobile.live.fr/hotmail/bouygues/
            • Renato Romero
              Hi Thierry A little oscillation around 50 Hz is normal: try to set a spectrogram software in high resolution at 50 Hz, a wip connected to the mic input, and
              Message 6 of 13 , Nov 6, 2006
                Hi Thierry
                A little oscillation around 50 Hz is normal: try to set a spectrogram
                software in high resolution at 50 Hz, a wip connected to the mic
                input, and you can see a continuos casual fluctuation of +/- 0.1 Hz.

                A drift of -1 Hz is not normal: it's an event!

                Bye, Renato


                At 13.43 06/11/2006, you wrote:

                >Hello Renato,
                >Thanks for the pictures...Whaouou 50 Hz moved a lot, how can it be ?
                >
                >Thierry.


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              • John Wilcoxen
                Renalto, I am also using two orthogonal loops with a negative impedance preamp. Do you have an article on your twin loop setup? I have seen your single minimal
                Message 7 of 13 , Nov 6, 2006
                  Renalto,
                  I am also using two orthogonal loops with a negative impedance preamp. Do you have an article on your twin loop setup? I have seen your single minimal loop article.
                  Thanks
                  John Wilcoxen (Tennessee, USA)

                  ----- Original Message -----
                  From: Renato Romero
                  To: VLF_Group@yahoogroups.com
                  Sent: Monday, November 06, 2006 12:03 PM
                  Subject: [VLF_Group] Overload in Germany's power network


                  From BBC web site 06 Nov/06:
                  "An overload in Germany's power network triggered outages leaving
                  millions without electricity on Saturday night."

                  Here my ELF monitoring from Cumiana (NW Italy)

                  http://www.vlf.it/temp/05NOV06-0000_E.jpg
                  Spectrogram by a geophone (up) and electric field (down)

                  http://www.vlf.it/temp/05NOV06-0000_H-rdf.jpg
                  RDF spectrogram, magnetic component, acquired with two orthogonal minimal loop

                  http://www.vlf.it/temp/fault.jpg
                  Details of the fault: power network frequency get down to 49 Hz for
                  many minutes,

                  http://www.vlf.it/temp/fault_timeb.jpg
                  Details in the time domain, about 240 mS showed

                  73, de ik1qfk
                  Renato Romero

                  --
                  No virus found in this outgoing message.
                  Checked by AVG Free Edition.
                  Version: 7.1.409 / Virus Database: 268.13.28/518 - Release Date: 04/11/2006





                  [Non-text portions of this message have been removed]
                • Renato Romero
                  Not Yet, I m working on an article but I m really busy with job. I hope for the end of this month. But the setup is easy: two minimal loops, with OP27
                  Message 8 of 13 , Nov 6, 2006
                    Not Yet,
                    I'm working on an article but I'm really busy with job. I hope for
                    the end of this month.

                    But the setup is easy: two minimal loops, with OP27 operational
                    amplifier as amplifier;
                    placed orthogonal in EW and NS direction.


                    Bye, Renato



                    At 14.18 06/11/2006, you wrote:

                    >Renalto,
                    >I am also using two orthogonal loops with a negative impedance
                    >preamp. Do you have an article on your twin loop setup? I have seen
                    >your single minimal loop article.
                    >Thanks
                    >John Wilcoxen (Tennessee, USA)


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                    No virus found in this outgoing message.
                    Checked by AVG Free Edition.
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                  • davep@quik.com
                    OT? Once upon a time, a long time ago, at a now departed domputer compnay... we had some disks, early, that used synchronous motors. And the data recovery
                    Message 9 of 13 , Nov 6, 2006
                      OT?

                      Once upon a time, a long time ago, at a now departed domputer compnay...

                      'we' had some disks, early, that used synchronous motors. And
                      the data recovery depended on that. Different settings for
                      Europe & US. Those sent to Europe seemed to fail a lot,
                      dat integrity, not hard/broken. Same units worked fine
                      on the lab 50Hz from the motor alternators, INCLUDING some
                      that had 'failed' in Europe & been returned for analysis.

                      Further investigation found:
                      Failures in Europe were always at 0200ish, local.

                      Further, further, it was found:
                      If US Power grid slips below (or above) freq, the
                      necessary cycles are added/subtracted, gently, over the course
                      of the day.

                      In Europe, seems the policy was to return to exactly 50.0000....,
                      Then, at 0200, when load was light an all were asleep, all
                      excess/missing cycles were put back in in short order...

                      (I make no assertion as to which is 'right'.)
                      best
                      dwp
                    • John Popelish
                      ... How can the frequency change? Some generators were accidentally switched off the grid. This caused an overload on the remaining units, and some of those
                      Message 10 of 13 , Nov 6, 2006
                        thierry alves wrote:
                        > Hello Renato,
                        > Thanks for the pictures...Whaouou 50 Hz moved a lot, how can it be ?

                        How can the frequency change? Some generators were
                        accidentally switched off the grid. This caused an overload
                        on the remaining units, and some of those probably tripped
                        off line because of the sudden overload. The remaining
                        units were also overloaded.

                        The torque on the generator shafts is proportional to the
                        power they are delivering. Throttling mechanisms (steam
                        valves, boiler fuel controls, etc.) went as far open as safe
                        operation allows, but could not bring the generators up to
                        full speed (without risking tripping additional units off
                        line on overload) till more units were brought back on line.
                        When enough generation capability was back on line, they
                        were brought back up to normal frequency (with a slight
                        overshoot to make up for some of the lost cycles).

                        This would be similar to having your car running on cruise
                        control (constant speed=constant frequency). Then one
                        cylinder stops firing. The power being delivered by the
                        remaining cylinders is not enough to maintain speed, which
                        sags. The cruise control attempts to bring the frequency
                        back up by increasing the power to the remaining cylinders,
                        but can't quite do it, so the speed levels off slightly
                        below the setpoint speed. Then the cylinder that stopped
                        firing starts working, again, and the speed returns to
                        normal, with a control overshoot. The difference with the
                        power grid, is that the additional capacity is added in
                        controlled amounts, not just slammed back on.
                      • Wolf DL4YHF
                        Hi Renato, Keep watching today ! They are just telling in the german news that the high-voltage line near the dock in Papenburg / northern DL will be switched
                        Message 11 of 13 , Nov 6, 2006
                          Hi Renato,

                          Keep watching today ! They are just telling in the german news that the
                          high-voltage line near the dock in Papenburg / northern DL will be
                          switched off again tonight (as a second attempt, to let a new ship pass
                          below, which will happen sometime after 19:00 UTC).

                          Of course, the spokesman said this time everything will work without a
                          problem, and no-one has to keep a torch / flashlight, candle or similar
                          in his hands during the evening ;-)

                          I will take a look at the 50 Hz mains too. Problem is my PC doesn't work
                          with battery power !

                          Best regards,
                          Wolf DL4YHF
                          (140 km away from "where the blackout started")
                        • Costas Krallis SV1XV
                          ... Very interesting Renato. Thanks. 73 Costas SV1XV
                          Message 12 of 13 , Nov 6, 2006
                            At 13:03 6/11/2006 +0100, you wrote:

                            > Here my ELF monitoring from Cumiana (NW Italy)


                            Very interesting Renato. Thanks.

                            73 Costas SV1XV
                          • Costas Krallis SV1XV
                            ... Power generators are designed with a negative frequency vs. power ouput characteristic, so when loading increases frequency drops. This is essential to
                            Message 13 of 13 , Nov 6, 2006
                              At 12:15 6/11/2006 -0500, you wrote:

                              > How can the frequency change?

                              Power generators are designed with a negative
                              frequency vs. power ouput characteristic, so when
                              loading increases frequency drops. This is essential
                              to allow generators to be connected in parallel.

                              73, Costas SV1XV
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