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Re: [softrock40] Measuring toroids inductance

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  • Jack Smith
    Simple PIC-based instruments measure inductance and capacitance at a rather low frequency compared with ham frequencies - in the 100-700 KHz range. However, an
    Message 1 of 14 , Nov 10, 2012
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      Simple PIC-based instruments measure inductance and capacitance at a rather low frequency compared with ham frequencies - in the 100-700 KHz range.

      However, an inductance value measured at say 500 KHz may or may not have a similar inductance at 5 or 25 MHz.

      Many factors enter in measured inductance versus frequency. Some are:

      1. Does the core material permeability vary with frequency? (Air, no; powdered iron, very little; ferrite material, permeability can change a great deal or a small amount with frequency depending on the particular mix.)

      2. Changes in current distribution - the winding current changes location to some degree with frequency due to skin effect and proximity effect, and as the current distribution changes, so does the inductance.

      3. Distributed capacitance - all inductors have distributed capacitance to one degree or another and as the test frequency approaches the self-resonance frequency of the inductor, the measured inductance will change, becoming very large, then zero at the SRF and negative above the SRF.

      Whether any or all of these factors are important cannot be answered in general abstract case; rather it depends on the details.

      As a rough statement, however, for inductors wound on powdered iron toroid cores and of typical values used in amateur radio construction and at frequencies in the 1-30 MHz range, a PIC-based instrument that measures inductance in the few hundred KHz range will produce useful results, with an error in the few percent range.

      I've written a detailed review of the AADE PIC-based L/C meter and discussed these factors in detail, as well as provided many measurement comparisons at
      http://www.cliftonlaboratories.com/Documents/AADE%20Reveiw.pdf

      Jack K8ZOA


      On 11/10/2012 7:57 AM, Malti wrote:
       

      With all due respect, there are scores of similar pic based circuits around.
      What I need is a pic based, but the coil measured under a high RF frequency.
      That is the only way to obtain very accurate readings, especially for us, at RF !
      Most use audio or slightly higher frequency, which is not enough  !

      Paul

      On 10 November 2012 11:59, John Rabson <john.rabson@...> wrote:
       

      Or try this:


      "the kit from G4HUP available from http://g4hup.com/LCM/LCMeter.htm which is only LC but excellent for measuring and matching caps including SM parts and winding coils for HF/VHF

      73
      John G4SWX"

      On 10 Nov 2012, at 11:27CET, pauldebono@... wrote:

       

      A few years ago, I came across a Russian inductance meter kit.
      Mnay designers claim to be the best one around for accurancy.

      Anyone has the details please ?
      Many of the popular meters around are dubious about accuracy, because inductance is not measured at RF, but anything but RF !

      Paul




    • Russ Ramirez
      I m sure the vast majority of people who have used the microcontroller-based LC meters will attest that given a rated off the shelf inductor or a wound coil of
      Message 2 of 14 , Nov 10, 2012
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        I'm sure the vast majority of people who have used the microcontroller-based LC meters will attest that given a rated off the shelf inductor or a wound coil of any type specified beforehand to be xx.xx nano/microhenries, their LC meters have been quite accurate. Indeed, if you wind a given toroid that calculations show should be 7.23 uH for the core used, the LC meters will display something within a few 10ths or so of 7.23 uH. I am an EE and well versed in the models we use, but have found it hard to argue with experience and successful outcomes :-) For most of the HF frequencies there is enough slop that it usually doesn't matter. UHF/SHF is another matter entirely.

        Russ
        K0WFS

        On Sat, Nov 10, 2012 at 8:07 AM, Jack Smith <Jack.Smith@...> wrote:
         

        Simple PIC-based instruments measure inductance and capacitance at a rather low frequency compared with ham frequencies - in the 100-700 KHz range.

        However, an inductance value measured at say 500 KHz may or may not have a similar inductance at 5 or 25 MHz.

        Many factors enter in measured inductance versus frequency. Some are:

        1. Does the core material permeability vary with frequency? (Air, no; powdered iron, very little; ferrite material, permeability can change a great deal or a small amount with frequency depending on the particular mix.)

        2. Changes in current distribution - the winding current changes location to some degree with frequency due to skin effect and proximity effect, and as the current distribution changes, so does the inductance.

        3. Distributed capacitance - all inductors have distributed capacitance to one degree or another and as the test frequency approaches the self-resonance frequency of the inductor, the measured inductance will change, becoming very large, then zero at the SRF and negative above the SRF.

        Whether any or all of these factors are important cannot be answered in general abstract case; rather it depends on the details.

        As a rough statement, however, for inductors wound on powdered iron toroid cores and of typical values used in amateur radio construction and at frequencies in the 1-30 MHz range, a PIC-based instrument that measures inductance in the few hundred KHz range will produce useful results, with an error in the few percent range.

        I've written a detailed review of the AADE PIC-based L/C meter and discussed these factors in detail, as well as provided many measurement comparisons at
        http://www.cliftonlaboratories.com/Documents/AADE%20Reveiw.pdf

        Jack K8ZOA


        On 11/10/2012 7:57 AM, Malti wrote:
         

        With all due respect, there are scores of similar pic based circuits around.
        What I need is a pic based, but the coil measured under a high RF frequency.
        That is the only way to obtain very accurate readings, especially for us, at RF !
        Most use audio or slightly higher frequency, which is not enough  !

        Paul

        On 10 November 2012 11:59, John Rabson <john.rabson@...> wrote:
         

        Or try this:


        "the kit from G4HUP available from http://g4hup.com/LCM/LCMeter.htm which is only LC but excellent for measuring and matching caps including SM parts and winding coils for HF/VHF

        73
        John G4SWX"

        On 10 Nov 2012, at 11:27CET, pauldebono@... wrote:

         

        A few years ago, I came across a Russian inductance meter kit.
        Mnay designers claim to be the best one around for accurancy.

        Anyone has the details please ?
        Many of the popular meters around are dubious about accuracy, because inductance is not measured at RF, but anything but RF !

        Paul





      • yl2gqn
        Hello Paul, I m use PC based software with very simple circuit. The accuracy is absolutely enough for radio amateurs. Original article is here:
        Message 3 of 14 , Nov 10, 2012
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          Hello Paul,

          I'm use PC based software with very simple circuit. The accuracy is absolutely enough for radio amateurs.

          Original article is here: http://www.sillanumsoft.org/ZRLC.htm
          Schematic can be grab from article on Italian: http://www.marucchi.it/ZRLC_web/INTERFACCIA_ZRLC_p.pdf

          Regards,
          Andy. YL2QN


          --- In softrock40@yahoogroups.com, "pauldebono@..." <pawlud@...> wrote:
          >
          > A few years ago, I came across a Russian inductance meter kit.
          > Mnay designers claim to be the best one around for accurancy.
          >
          > Anyone has the details please ?
          > Many of the popular meters around are dubious about accuracy, because inductance is not measured at RF, but anything but RF !
          >
          > Paul
          >
        • rifkum
          I just bought and used one of these...
          Message 4 of 14 , Nov 10, 2012
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            I just bought and used one of these...

            http://www.ebay.com/itm/LC100-A-Digital-LCD-High-Precision-Inductance-Capacitance-L-C-multimeter-Meter-/271036658278?pt=LH_DefaultDomain_0&hash=item3f1b0b3266

            to build my ensemble RX II.

            I am extremely pleased with it. Runs off of USB power (cable included) or there is an external power jack. The USB is only used for power, no data back to the computer required.

            Seems very accurate... easy to use. All the capacitors checked out as marked and the toroids came out as they were supposed to according to the build plans and number of turns.

            Be sure to zero it each time you turn it on (I zero it before each reading)

            There are several on ebay.

            I am very pleased with this one though.

            good luck
            dwight
            N7KBC
          • Zack Widup
            I also bought one of these. I am also very impressed. Hand-wound inductances and toroids measure within a few percent of the calculated value. I made a little
            Message 5 of 14 , Nov 10, 2012
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              I also bought one of these. I am also very impressed. Hand-wound inductances and toroids measure within a few percent of the calculated value. I made a little clip jig to measure chip components with. Very handy.

              73, Zack W9SZ


              On Sat, Nov 10, 2012 at 11:21 AM, rifkum <rifkum@...> wrote:
               

              I just bought and used one of these...

              http://www.ebay.com/itm/LC100-A-Digital-LCD-High-Precision-Inductance-Capacitance-L-C-multimeter-Meter-/271036658278?pt=LH_DefaultDomain_0&hash=item3f1b0b3266

              to build my ensemble RX II.

              I am extremely pleased with it. Runs off of USB power (cable included) or there is an external power jack. The USB is only used for power, no data back to the computer required.

              Seems very accurate... easy to use. All the capacitors checked out as marked and the toroids came out as they were supposed to according to the build plans and number of turns.

              Be sure to zero it each time you turn it on (I zero it before each reading)

              There are several on ebay.

              I am very pleased with this one though.

              good luck
              dwight
              N7KBC


            • Ricardo Caratti
              Helo everybody.   I also bought one of these on ebay. I posted a video showing that this device working. Softrock VHF RX Ensemble II 8/10 (T2 Wind) -
              Message 6 of 14 , Nov 10, 2012
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                Helo everybody.
                 
                I also bought one of these on ebay.
                I posted a video showing that this device working.
                Softrock VHF RX Ensemble II 8/10 (T2 Wind) - http://youtu.be/3zKYe7ak-2U

                73.
                PU2CLR.
                Ricardo.




                De: rifkum <rifkum@...>
                Para: softrock40@yahoogroups.com
                Enviadas: Sábado, 10 de Novembro de 2012 15:21
                Assunto: [softrock40] Re: Measuring toroids inductance

                 
                I just bought and used one of these...

                http://www.ebay.com/itm/LC100-A-Digital-LCD-High-Precision-Inductance-Capacitance-L-C-multimeter-Meter-/271036658278?pt=LH_DefaultDomain_0&hash=item3f1b0b3266

                to build my ensemble RX II.

                I am extremely pleased with it. Runs off of USB power (cable included) or there is an external power jack. The USB is only used for power, no data back to the computer required.

                Seems very accurate... easy to use. All the capacitors checked out as marked and the toroids came out as they were supposed to according to the build plans and number of turns.

                Be sure to zero it each time you turn it on (I zero it before each reading)

                There are several on ebay.

                I am very pleased with this one though.

                good luck
                dwight
                N7KBC



              • Malti
                This LCR meter has been reviewed by N5ESE, and looks promising, but it seems the company has gone bust ! Its the M-Cubed LCRZ Meter Paul ... This LCR meter
                Message 7 of 14 , Nov 11, 2012
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                  This LCR meter has been reviewed by N5ESE, and looks promising, but it seems the company has gone bust !

                   Its the  M-Cubed LCRZ Meter

                  Paul

                  On 10 November 2012 22:16, Ricardo Caratti <pu2clr@...> wrote:
                   

                  Helo everybody.
                   
                  I also bought one of these on ebay.
                  I posted a video showing that this device working.
                  Softrock VHF RX Ensemble II 8/10 (T2 Wind) - http://youtu.be/3zKYe7ak-2U

                  73.
                  PU2CLR.
                  Ricardo.




                  De: rifkum <rifkum@...>
                  Para: softrock40@yahoogroups.com
                  Enviadas: Sábado, 10 de Novembro de 2012 15:21
                  Assunto: [softrock40] Re: Measuring toroids inductance

                   
                  I just bought and used one of these...

                  http://www.ebay.com/itm/LC100-A-Digital-LCD-High-Precision-Inductance-Capacitance-L-C-multimeter-Meter-/271036658278?pt=LH_DefaultDomain_0&hash=item3f1b0b3266

                  to build my ensemble RX II.

                  I am extremely pleased with it. Runs off of USB power (cable included) or there is an external power jack. The USB is only used for power, no data back to the computer required.

                  Seems very accurate... easy to use. All the capacitors checked out as marked and the toroids came out as they were supposed to according to the build plans and number of turns.

                  Be sure to zero it each time you turn it on (I zero it before each reading)

                  There are several on ebay.

                  I am very pleased with this one though.

                  good luck
                  dwight
                  N7KBC




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