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Inverter unit RFI fixed!

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  • Geoff Dudley <gdudley@gpo.swin.edu.au>
    Hi Group, You may recall that I had a problem when I went away to S.A. for the total solar eclipse. My inverter unit (12v to 240v) gave off extremely high
    Message 1 of 5 , Feb 1, 2003
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      Hi Group,

      You may recall that I had a problem when I went away to S.A. for the
      total solar eclipse. My inverter unit (12v to 240v) gave off extremely
      high levels of RFI, to the point that a lot of the received WWVH
      signal was blotted out, rendering the tape fairly useless for
      scientific purposes.

      This was a real bummer to an exercise which so far had proceeded well.
      (see:
      http://astronomy.swin.edu.au/solar_eclipse_2002/gallery/dudley.html )

      I'm pleased to say that this problem is now fixed. I took the advice
      of a friend of mine who is the Director of the Radio Astronomy Section
      , Astronomical Society of Victoria, Australia. What he suggested was
      to isolate the inverter unit by wrapping it in metallic flywire mesh
      and then placing it into a metal toolbox. That worked, but I was still
      not completely happy. So I put the 240v output lead thru a
      ferromagnetic bead. The bead I used was an AMIDON material #43, part
      number 2X43-251P2. It wasn't my first choice, I wanted to use material
      #75, which is suitable below 30MHz, but I couldn't buy it anywhere.
      (Material #43 is suitable for frequencies between 40-200MHz). It cost
      $AUS8-50)

      I used a different ferromagnetic bead on the 12v lead. Unfortunately
      the specs didn't say what the maximum permeability was at 25MHz,but
      the impedance was quite high, 169uH, so I used it. That seemed to do
      the trick. The result is quite dramatic. The RF hash has practically
      gone. There is still a low frequency "tick tick tick" sound coming
      thru the audio of the radio, but at least WWVH is completely audible
      and I'm happy.

      I got my AMIDON ferrite from the equivalent of your Radio Shack ("Dick
      Smith Electronics") The AMIDON company address is P.O. Box 6122,
      Irvine, CA 92616

      --Geoff
    • Paul Steckler
      ... Yes, I have a box of electronic doodads I bought at Dick Smith s when I lived in Sydney. Can I interest anyone in a used 240V alarm clock? Universal Radio
      Message 2 of 5 , Feb 1, 2003
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        > I got my AMIDON ferrite from the equivalent of your Radio
        > Shack ("Dick
        > Smith Electronics") The AMIDON company address is P.O. Box 6122,
        > Irvine, CA 92616

        Yes, I have a box of electronic doodads I bought at Dick Smith's
        when I lived in Sydney. Can I interest anyone in a used 240V alarm
        clock?

        Universal Radio has a Web page of Amidon items, including
        ferrite beads:

        http://www.universal-radio.com/catalog/misc/amidon.html

        -- Paul
      • William H. Bowen
        Geoff, If Radio Shack where 1/10 the place Dick Smith s is, you d hear a cheer from experimenters in this country so loud you d hear it in Australia. Bill
        Message 3 of 5 , Feb 1, 2003
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          Geoff,

          If Radio Shack where 1/10 the place Dick
          Smith's is, you'd hear a cheer from
          experimenters in this country so loud you'd
          hear it in Australia.

          Bill Bowen

          To: Sangean803@yahoogroups.com
          From: "Geoff Dudley <gdudley@...>" <gdudley@...>
          Date sent: Sat, 01 Feb 2003 11:27:21 -0000
          Subject: [Sangean803] Inverter unit RFI fixed!
          Send reply to: Sangean803@yahoogroups.com

          >
          > Hi Group,
          >
          > You may recall that I had a problem when I went away to S.A. for the
          > total solar eclipse. My inverter unit (12v to 240v) gave off extremely
          > high levels of RFI, to the point that a lot of the received WWVH
          > signal was blotted out, rendering the tape fairly useless for
          > scientific purposes.
          >
          > This was a real bummer to an exercise which so far had proceeded well.
          > (see:
          > http://astronomy.swin.edu.au/solar_eclipse_2002/gallery/dudley.html )
          >
          > I'm pleased to say that this problem is now fixed. I took the advice
          > of a friend of mine who is the Director of the Radio Astronomy Section
          > , Astronomical Society of Victoria, Australia. What he suggested was
          > to isolate the inverter unit by wrapping it in metallic flywire mesh
          > and then placing it into a metal toolbox. That worked, but I was still
          > not completely happy. So I put the 240v output lead thru a
          > ferromagnetic bead. The bead I used was an AMIDON material #43, part
          > number 2X43-251P2. It wasn't my first choice, I wanted to use material
          > #75, which is suitable below 30MHz, but I couldn't buy it anywhere.
          > (Material #43 is suitable for frequencies between 40-200MHz). It cost
          > $AUS8-50)
          >
          > I used a different ferromagnetic bead on the 12v lead. Unfortunately
          > the specs didn't say what the maximum permeability was at 25MHz,but
          > the impedance was quite high, 169uH, so I used it. That seemed to do
          > the trick. The result is quite dramatic. The RF hash has practically
          > gone. There is still a low frequency "tick tick tick" sound coming
          > thru the audio of the radio, but at least WWVH is completely audible
          > and I'm happy.
          >
          > I got my AMIDON ferrite from the equivalent of your Radio Shack ("Dick
          > Smith Electronics") The AMIDON company address is P.O. Box 6122,
          > Irvine, CA 92616
          >
          > --Geoff
          >
          >
          > To unsubscribe from this group, send an email to:
          > Sangean803-unsubscribe@yahoogroups.com
          >
          >
          >
          > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
          >
          >
        • William H. Bowen
          Geoff, If Radio Shack where 1/10 the place that Dick Smith s is, there would be a cheer from the experimenters in this country so loud you d hear it all the
          Message 4 of 5 , Feb 1, 2003
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            Geoff,

            If Radio Shack where 1/10 the place that
            Dick Smith's is, there would be a cheer from
            the experimenters in this country so loud
            you'd hear it all the way "Down Under".

            Unfortuanately, RS is going the other
            direction, becoming nothing more than a
            glorified consumer electronics (stereo, TV,
            cell phone and satellite TV) peddler.

            Regards,
            Bill Bowen
            bill_bowen@...
            Sacramento, CA USA

            To: Sangean803@yahoogroups.com
            From: "Geoff Dudley <gdudley@...>" <gdudley@...>
            Date sent: Sat, 01 Feb 2003 11:27:21 -0000
            Subject: [Sangean803] Inverter unit RFI fixed!
            Send reply to: Sangean803@yahoogroups.com

            >
            > Hi Group,
            >
            > You may recall that I had a problem when I went away to S.A. for the
            > total solar eclipse. My inverter unit (12v to 240v) gave off extremely
            > high levels of RFI, to the point that a lot of the received WWVH
            > signal was blotted out, rendering the tape fairly useless for
            > scientific purposes.
            >
            > This was a real bummer to an exercise which so far had proceeded well.
            > (see:
            > http://astronomy.swin.edu.au/solar_eclipse_2002/gallery/dudley.html )
            >
            > I'm pleased to say that this problem is now fixed. I took the advice
            > of a friend of mine who is the Director of the Radio Astronomy Section
            > , Astronomical Society of Victoria, Australia. What he suggested was
            > to isolate the inverter unit by wrapping it in metallic flywire mesh
            > and then placing it into a metal toolbox. That worked, but I was still
            > not completely happy. So I put the 240v output lead thru a
            > ferromagnetic bead. The bead I used was an AMIDON material #43, part
            > number 2X43-251P2. It wasn't my first choice, I wanted to use material
            > #75, which is suitable below 30MHz, but I couldn't buy it anywhere.
            > (Material #43 is suitable for frequencies between 40-200MHz). It cost
            > $AUS8-50)
            >
            > I used a different ferromagnetic bead on the 12v lead. Unfortunately
            > the specs didn't say what the maximum permeability was at 25MHz,but
            > the impedance was quite high, 169uH, so I used it. That seemed to do
            > the trick. The result is quite dramatic. The RF hash has practically
            > gone. There is still a low frequency "tick tick tick" sound coming
            > thru the audio of the radio, but at least WWVH is completely audible
            > and I'm happy.
            >
            > I got my AMIDON ferrite from the equivalent of your Radio Shack ("Dick
            > Smith Electronics") The AMIDON company address is P.O. Box 6122,
            > Irvine, CA 92616
            >
            > --Geoff
            >
            >
            > To unsubscribe from this group, send an email to:
            > Sangean803-unsubscribe@yahoogroups.com
            >
            >
            >
            > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
            >
            >
          • William H. Bowen
            Geoff, If Radio Shack where 1/10 the place that Dick Smith s is, there would be a cheer from the experimenters in this country so loud you d hear it all the
            Message 5 of 5 , Feb 1, 2003
            • 0 Attachment
              Geoff,

              If Radio Shack where 1/10 the place that
              Dick Smith's is, there would be a cheer from
              the experimenters in this country so loud
              you'd hear it all the way "Down Under".

              Unfortuanately, RS is going the other
              direction, becoming nothing more than a
              glorified consumer electronics (stereo, TV,
              cell phone and satellite TV) peddler.

              Regards,
              Bill Bowen
              bill_bowen@...
              Sacramento, CA USA

              To: Sangean803@yahoogroups.com
              From: "Geoff Dudley <gdudley@...>" <gdudley@...>
              Date sent: Sat, 01 Feb 2003 11:27:21 -0000
              Subject: [Sangean803] Inverter unit RFI fixed!
              Send reply to: Sangean803@yahoogroups.com

              >
              > Hi Group,
              >
              > You may recall that I had a problem when I went away to S.A. for the
              > total solar eclipse. My inverter unit (12v to 240v) gave off extremely
              > high levels of RFI, to the point that a lot of the received WWVH
              > signal was blotted out, rendering the tape fairly useless for
              > scientific purposes.
              >
              > This was a real bummer to an exercise which so far had proceeded well.
              > (see:
              > http://astronomy.swin.edu.au/solar_eclipse_2002/gallery/dudley.html )
              >
              > I'm pleased to say that this problem is now fixed. I took the advice
              > of a friend of mine who is the Director of the Radio Astronomy Section
              > , Astronomical Society of Victoria, Australia. What he suggested was
              > to isolate the inverter unit by wrapping it in metallic flywire mesh
              > and then placing it into a metal toolbox. That worked, but I was still
              > not completely happy. So I put the 240v output lead thru a
              > ferromagnetic bead. The bead I used was an AMIDON material #43, part
              > number 2X43-251P2. It wasn't my first choice, I wanted to use material
              > #75, which is suitable below 30MHz, but I couldn't buy it anywhere.
              > (Material #43 is suitable for frequencies between 40-200MHz). It cost
              > $AUS8-50)
              >
              > I used a different ferromagnetic bead on the 12v lead. Unfortunately
              > the specs didn't say what the maximum permeability was at 25MHz,but
              > the impedance was quite high, 169uH, so I used it. That seemed to do
              > the trick. The result is quite dramatic. The RF hash has practically
              > gone. There is still a low frequency "tick tick tick" sound coming
              > thru the audio of the radio, but at least WWVH is completely audible
              > and I'm happy.
              >
              > I got my AMIDON ferrite from the equivalent of your Radio Shack ("Dick
              > Smith Electronics") The AMIDON company address is P.O. Box 6122,
              > Irvine, CA 92616
              >
              > --Geoff
              >
              >
              > To unsubscribe from this group, send an email to:
              > Sangean803-unsubscribe@yahoogroups.com
              >
              >
              >
              > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
              >
              >
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