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Another Mark Keppinger Theremin is Born

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  • jrwatts4
    Well after a little more than a year of off-an-on progress I finally finished it and I m very pleased with the result. I posted a photo album of the finished
    Message 1 of 9 , Mar 1, 2011
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      Well after a little more than a year of off-an-on progress I finally finished it and I'm very pleased with the result.  I posted a photo album of the finished Theremin in this group's Photos folder.  I believe this chassis set is the last of the original batch from Mark by way of Kyle.  For the group's reference, I posted two documents with chassis dimensions in this group's Files folder.

      I would like to thank Mark and Kyle for their generous guidance early on and to Phillip for making his very helpful experience available on his website.  I followed the J. Sparks schematics (Rev 7 – dated 12/20/2008) closely and made no electronic changes.  I'm very happy to report that it worked very well from the moment I first plugged it in.  No problems with the oscillators (knock on wood), they seem rock solid.  It sings beautifully.  The wave forms are clean and display similar to those on Phillip's website.  

      I did incorporate a few parts and layout enhancements partly based on comments of previous builders: 
      It was commented that the 3K resistor in the power supply can get hot so I installed a 50 watt with heat-sink mounted to the chassis.  As you might guess, it runs very cool.  In fact all the components run very cool (except the tubes of course).

      To make the oscillator trimmers more accessible, I mounted them upside-down on the terminal strip and drilled holes through the top of the chassis to make the adjustment.  I inserted a grommet in each hole to help guide the non-metallic screwdriver to the adjustment screw.  It works quite well.  

      In the pitch and tone oscillators, I installed a 500pf capacitor in each for Concert Tuning (that was as close to 430pf as I had).  I then piggy backed each capacitor with an additional a 200pf in the pitch oscillator and a 250pf in the tone oscillator.  Now I can easily experiment back and forth from Concert to Bass by just taking the piggy packed caps in and out of circuit.

      I crafted and applied decal labels to both chassis' to identify the controls and tubes.  I also included a decal indicating its a Mark Keppinger design.

      Until I have a cabinet constructed, the chassis's will be open and exposed.  To keep small grandchildren's hands out of bad places, I made black perforated aluminum covers that completely cover the bottom and sides of each chassis.  The pattern of 3/16" perforations on 1/4" centers allow more than sufficient ventilation.  The covers aren't shown in the photos.

      The wiring is cloth reproduction wire from Radio Daze.  The chassis's are painted with Hammer-tone Copper.
      Part of the delay in getting the build done was first making a coil winder (reference photo in the gallery).  I used a motor drive using a motor with a gear reduction to 20 rpm and providing sufficient torque (purchased on Antique Radio Forums).  I utilized an inexpensive belt and pulleys (available on Amazon) to have the ability to adjust the speed if needed.  I use a digital counter I found on Ebay.  The coil winder and motor drive worked very well and efficiently – I was able to wind all the coils in just a couple hours.  

      My next project is to make the antennas.  I currently have a Mickey Mouse version that I fashioned from 14 gauge electrical ground wire.  It works for the moment.  I have read various posts regarding making a reproduction RCA antenna – If anyone has a relatively easy approach to this or pitfalls I should avoid please let me know.  

      I will also tackle making a cabinet.  I'm considering incorporating a 10" speaker but also trying to keep the design suggestive of the RCA Theremin – not sure yet how to accomplish both.

      Guidance needed:  I need some perspectives in adjusting the various trimmers, etc.  I've found they interact enough that I'm not sure if any of my adjustments are optimal or that I'm converging on the most accurate overall adjustment.  I would appreciate any insights – ideally if you have a tried and true procedure to methodically or iteratively accomplish this please let me know.  Also what tests or symptoms have you found that indicate misalignment?

      Regards,

      Richard Watts
    • mkepp@hevanet.com
      Richard; Congrats on a job well done! You have joined the elite although growing group of those who have completed a Theremin based on my design. Back when I
      Message 2 of 9 , Mar 1, 2011
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        Richard;

        Congrats on a job well done! You have joined the elite although growing
        group of those who have completed a Theremin based on my design. Back
        when I made my schematic public domain, I figured that one or two people
        might attempt this undertaking and then eventually give up. I never
        dreamed that not only would there be this many success stories, but that
        those who embarked on this path would share their experiences and help
        others that followed them. How cool is that!?

        I don't think that there is going to be a perfect set of oscillator
        frequencies that works for everyone in all locations; mostly because AM
        radio transmitters are going to hetrodyne with the oscillators and
        produce "birdies" (unwanted byproducts of RF signals mixing).
        Experimenting with the tuning is truly your best bet. When you find
        something that works for you, document it if possible, and you can always
        go back to it at a later time.

        Mark Keppinger

        > Well after a little more than a year of off-an-on progress I finally
        > finished it and I'm very pleased with the result. I posted a photo
        > album of the finished Theremin in this group's Photos folder. I
        > believe this chassis set is the last of the original batch from Mark by
        > way of Kyle. For the group's reference, I posted two documents with
        > chassis dimensions in this group's Files folder.
        >
        > I would like to thank Mark and Kyle for their generous guidance early on
        > and to Phillip for making his very helpful experience available on his
        > website. I followed the J. Sparks schematics (Rev 7 � dated
        > 12/20/2008) closely and made no electronic changes. I'm very happy
        > to report that it worked very well from the moment I first plugged it
        > in. No problems with the oscillators (knock on wood), they seem rock
        > solid. It sings beautifully. The wave forms are clean and display
        > similar to those on Phillip's website.
        >
        > I did incorporate a few parts and layout enhancements partly based on
        > comments of previous builders:
        > It was commented that the 3K resistor in the power supply can get hot so
        > I installed a 50 watt with heat-sink mounted to the chassis. As you
        > might guess, it runs very cool. In fact all the components run very
        > cool (except the tubes of course).
        >
        > To make the oscillator trimmers more accessible, I mounted them
        > upside-down on the terminal strip and drilled holes through the top of
        > the chassis to make the adjustment. I inserted a grommet in each hole
        > to help guide the non-metallic screwdriver to the adjustment screw. It
        > works quite well.
        >
        > In the pitch and tone oscillators, I installed a 500pf capacitor in each
        > for Concert Tuning (that was as close to 430pf as I had). I then piggy
        > backed each capacitor with an additional a 200pf in the pitch oscillator
        > and a 250pf in the tone oscillator. Now I can easily experiment back
        > and forth from Concert to Bass by just taking the piggy packed caps in
        > and out of circuit.
        >
        > I crafted and applied decal labels to both chassis' to identify the
        > controls and tubes. I also included a decal indicating its a Mark
        > Keppinger design.
        >
        > Until I have a cabinet constructed, the chassis's will be open and
        > exposed. To keep small grandchildren's hands out of bad places, I made
        > black perforated aluminum covers that completely cover the bottom and
        > sides of each chassis. The pattern of 3/16" perforations on 1/4"
        > centers allow more than sufficient ventilation. The covers aren't shown
        > in the photos.
        >
        > The wiring is cloth reproduction wire from Radio Daze. The chassis's
        > are painted with Hammer-tone Copper.
        > Part of the delay in getting the build done was first making a coil
        > winder (reference photo in the gallery). I used a motor drive using a
        > motor with a gear reduction to 20 rpm and providing sufficient torque
        > (purchased on Antique Radio Forums). I utilized an inexpensive belt and
        > pulleys (available on Amazon) to have the ability to adjust the speed if
        > needed. I use a digital counter I found on Ebay. The coil winder and
        > motor drive worked very well and efficiently � I was able to wind
        > all the coils in just a couple hours.
        >
        > My next project is to make the antennas. I currently have a Mickey
        > Mouse version that I fashioned from 14 gauge electrical ground wire. It
        > works for the moment. I have read various posts regarding making a
        > reproduction RCA antenna � If anyone has a relatively easy approach
        > to this or pitfalls I should avoid please let me know.
        >
        > I will also tackle making a cabinet. I'm considering incorporating
        > a 10" speaker but also trying to keep the design suggestive of the
        > RCA Theremin � not sure yet how to accomplish both.
        >
        > Guidance needed: I need some perspectives in adjusting the various
        > trimmers, etc. I've found they interact enough that I'm not
        > sure if any of my adjustments are optimal or that I'm converging on
        > the most accurate overall adjustment. I would appreciate any insights
        > � ideally if you have a tried and true procedure to methodically or
        > iteratively accomplish this please let me know. Also what tests or
        > symptoms have you found that indicate misalignment?
        >
        > Regards,
        >
        > Richard Watts
        >
        >
      • Jean Lucas
        Hi Richard, Congratulations for your work! The wiring looks perfect, and your coil winder seems great too ! I have a question about the octal plug you use : I
        Message 3 of 9 , Mar 2, 2011
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          Hi Richard,

          Congratulations for your work! The wiring looks perfect, and your coil winder seems great too !

          I have a question about the octal plug you use : I was planning to use a tube base for my (future) Keppinger Theremin building, but it's not very satisfactory because it's open. On the contrary, your plug is closed. Did you build it from a "standart" tube base or did you find another kind of octal plug ? If yes, could you tell me where ?

          All the best
           
          Jean LUCAS



          De : jrwatts4 <jrwatts@...>
          À : kepptheremins@yahoogroups.com
          Envoyé le : Mer 2 mars 2011, 3h 17min 37s
          Objet : [kepptheremins] Another Mark Keppinger Theremin is Born

           

          Well after a little more than a year of off-an-on progress I finally finished it and I'm very pleased with the result.  I posted a photo album of the finished Theremin in this group's Photos folder.  I believe this chassis set is the last of the original batch from Mark by way of Kyle.  For the group's reference, I posted two documents with chassis dimensions in this group's Files folder.

          I would like to thank Mark and Kyle for their generous guidance early on and to Phillip for making his very helpful experience available on his website.  I followed the J. Sparks schematics (Rev 7 – dated 12/20/2008) closely and made no electronic changes.  I'm very happy to report that it worked very well from the moment I first plugged it in.  No problems with the oscillators (knock on wood), they seem rock solid.  It sings beautifully.  The wave forms are clean and display similar to those on Phillip's website.  

          I did incorporate a few parts and layout enhancements partly based on comments of previous builders: 

          It was commented that the 3K resistor in the power supply can get hot so I installed a 50 watt with heat-sink mounted to the chassis.  As you might guess, it runs very cool.  In fact all the components run very cool (except the tubes of course).

          To make the oscillator trimmers more accessible, I mounted them upside-down on the terminal strip and drilled holes through the top of the chassis to make the adjustment.  I inserted a grommet in each hole to help guide the non-metallic screwdriver to the adjustment screw.  It works quite well.  

          In the pitch and tone oscillators, I installed a 500pf capacitor in each for Concert Tuning (that was as close to 430pf as I had).  I then piggy backed each capacitor with an additional a 200pf in the pitch oscillator and a 250pf in the tone oscillator.  Now I can easily experiment back and forth from Concert to Bass by just taking the piggy packed caps in and out of circuit.

          I crafted and applied decal labels to both chassis' to identify the controls and tubes.  I also included a decal indicating its a Mark Keppinger design.

          Until I have a cabinet constructed, the chassis's will be open and exposed.  To keep small grandchildren's hands out of bad places, I made black perforated aluminum covers that completely cover the bottom and sides of each chassis.  The pattern of 3/16" perforations on 1/4" centers allow more than sufficient ventilation.  The covers aren't shown in the photos.

          The wiring is cloth reproduction wire from Radio Daze.  The chassis's are painted with Hammer-tone Copper.
          Part of the delay in getting the build done was first making a coil winder (reference photo in the gallery).  I used a motor drive using a motor with a gear reduction to 20 rpm and providing sufficient torque (purchased on Antique Radio Forums).  I utilized an inexpensive belt and pulleys (available on Amazon) to have the ability to adjust the speed if needed.  I use a digital counter I found on Ebay.  The coil winder and motor drive worked very well and efficiently – I was able to wind all the coils in just a couple hours.  

          My next project is to make the antennas.  I currently have a Mickey Mouse version that I fashioned from 14 gauge electrical ground wire.  It works for the moment.  I have read various posts regarding making a reproduction RCA antenna – If anyone has a relatively easy approach to this or pitfalls I should avoid please let me know.  

          I will also tackle making a cabinet.  I'm considering incorporating a 10" speaker but also trying to keep the design suggestive of the RCA Theremin – not sure yet how to accomplish both.

          Guidance needed:  I need some perspectives in adjusting the various trimmers, etc.  I've found they interact enough that I'm not sure if any of my adjustments are optimal or that I'm converging on the most accurate overall adjustment.  I would appreciate any insights – ideally if you have a tried and true procedure to methodically or iteratively accomplish this please let me know.  Also what tests or symptoms have you found that indicate misalignment?

          Regards,

          Richard Watts


        • Richard Watts
          Mark and Jean, thank you for the kind words. Jean the octal plug is vintage 1940s/50s and is made with a groove around the circumference to hold the snap on
          Message 4 of 9 , Mar 2, 2011
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            Mark and Jean, thank you for the kind words.

             

            Jean the octal plug is vintage 1940s/50s and is made with a groove around the circumference to hold the snap on cap.  The cap didn’t have a hole for the cable so I had to drill it and insert a grommet.  I found the plug and cap at a radio club swap meet for $1.

             

            Regards,

             

            Richard

             

            From: kepptheremins@yahoogroups.com [mailto:kepptheremins@yahoogroups.com] On Behalf Of Jean Lucas
            Sent: Wednesday, March 02, 2011 11:01 AM
            To: kepptheremins@yahoogroups.com
            Subject: Re : [kepptheremins] Another Mark Keppinger Theremin is Born

             

             

            Hi Richard,

            Congratulations for your work! The wiring looks perfect, and your coil winder seems great too !

            I have a question about the octal plug you use : I was planning to use a tube base for my (future) Keppinger Theremin building, but it's not very satisfactory because it's open. On the contrary, your plug is closed. Did you build it from a "standart" tube base or did you find another kind of octal plug ? If yes, could you tell me where ?

            All the best

             

            Jean LUCAS

             

             


            De : jrwatts4 <jrwatts@...>
            À : kepptheremins@yahoogroups.com
            Envoyé le : Mer 2 mars 2011, 3h 17min 37s
            Objet : [kepptheremins] Another Mark Keppinger Theremin is Born

             

            Well after a little more than a year of off-an-on progress I finally finished it and I'm very pleased with the result.  I posted a photo album of the finished Theremin in this group's Photos folder.  I believe this chassis set is the last of the original batch from Mark by way of Kyle.  For the group's reference, I posted two documents with chassis dimensions in this group's Files folder.

            I would like to thank Mark and Kyle for their generous guidance early on and to Phillip for making his very helpful experience available on his website.  I followed the J. Sparks schematics (Rev 7 – dated 12/20/2008) closely and made no electronic changes.  I'm very happy to report that it worked very well from the moment I first plugged it in.  No problems with the oscillators (knock on wood), they seem rock solid.  It sings beautifully.  The wave forms are clean and display similar to those on Phillip's website.  

            I did incorporate a few parts and layout enhancements partly based on comments of previous builders: 

            It was commented that the 3K resistor in the power supply can get hot so I installed a 50 watt with heat-sink mounted to the chassis.  As you might guess, it runs very cool.  In fact all the components run very cool (except the tubes of course).

            To make the oscillator trimmers more accessible, I mounted them upside-down on the terminal strip and drilled holes through the top of the chassis to make the adjustment.  I inserted a grommet in each hole to help guide the non-metallic screwdriver to the adjustment screw.  It works quite well.  

            In the pitch and tone oscillators, I installed a 500pf capacitor in each for Concert Tuning (that was as close to 430pf as I had).  I then piggy backed each capacitor with an additional a 200pf in the pitch oscillator and a 250pf in the tone oscillator.  Now I can easily experiment back and forth from Concert to Bass by just taking the piggy packed caps in and out of circuit.

            I crafted and applied decal labels to both chassis' to identify the controls and tubes.  I also included a decal indicating its a Mark Keppinger design.

            Until I have a cabinet constructed, the chassis's will be open and exposed.  To keep small grandchildren's hands out of bad places, I made black perforated aluminum covers that completely cover the bottom and sides of each chassis.  The pattern of 3/16" perforations on 1/4" centers allow more than sufficient ventilation.  The covers aren't shown in the photos.

            The wiring is cloth reproduction wire from Radio Daze.  The chassis's are painted with Hammer-tone Copper.

            Part of the delay in getting the build done was first making a coil winder (reference photo in the gallery).  I used a motor drive using a motor with a gear reduction to 20 rpm and providing sufficient torque (purchased on Antique Radio Forums).  I utilized an inexpensive belt and pulleys (available on Amazon) to have the ability to adjust the speed if needed.  I use a digital counter I found on Ebay.  The coil winder and motor drive worked very well and efficiently – I was able to wind all the coils in just a couple hours.  

            My next project is to make the antennas.  I currently have a Mickey Mouse version that I fashioned from 14 gauge electrical ground wire.  It works for the moment.  I have read various posts regarding making a reproduction RCA antenna – If anyone has a relatively easy approach to this or pitfalls I should avoid please let me know.  

            I will also tackle making a cabinet.  I'm considering incorporating a 10" speaker but also trying to keep the design suggestive of the RCA Theremin – not sure yet how to accomplish both.

            Guidance needed:  I need some perspectives in adjusting the various trimmers, etc.  I've found they interact enough that I'm not sure if any of my adjustments are optimal or that I'm converging on the most accurate overall adjustment.  I would appreciate any insights – ideally if you have a tried and true procedure to methodically or iteratively accomplish this please let me know.  Also what tests or symptoms have you found that indicate misalignment?

            Regards,

            Richard Watts

             

          • Jean Lucas
            Richard, thanks for your answer. Concerning the antennas, you may know that Mike Buffington has built several RCA reproduction antenna sets, as you can see
            Message 5 of 9 , Mar 3, 2011
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              Richard,

              thanks for your answer.
              Concerning the antennas, you may know that Mike Buffington has built several RCA reproduction antenna sets, as you can see here:RCA Theremin Replica Antenna Construction 
              Maybe could he give you some tips ? His antennas seem to be very well built.

              Personnally, I was planning to use brass or copper rod that I would thread, which eliminates the need for a lathe, like on the "original" Keppinger theremins.

              all the best

              Jean



              De : Richard Watts <jrwatts@...>
              À : kepptheremins@yahoogroups.com
              Envoyé le : Mer 2 mars 2011, 20h 31min 05s
              Objet : RE: [kepptheremins] Another Mark Keppinger Theremin is Born

               

              Mark and Jean, thank you for the kind words.

               

              Jean the octal plug is vintage 1940s/50s and is made with a groove around the circumference to hold the snap on cap.  The cap didn’t have a hole for the cable so I had to drill it and insert a grommet.  I found the plug and cap at a radio club swap meet for $1.

               

              Regards,

               

              Richard

               

              From: kepptheremins@yahoogroups.com [mailto:kepptheremins@yahoogroups.com] On Behalf Of Jean Lucas
              Sent: Wednesday, March 02, 2011 11:01 AM
              To: kepptheremins@yahoogroups.com
              Subject: Re : [kepptheremins] Another Mark Keppinger Theremin is Born

               

               

              Hi Richard,

              Congratulations for your work! The wiring looks perfect, and your coil winder seems great too !

              I have a question about the octal plug you use : I was planning to use a tube base for my (future) Keppinger Theremin building, but it's not very satisfactory because it's open. On the contrary, your plug is closed. Did you build it from a "standart" tube base or did you find another kind of octal plug ? If yes, could you tell me where ?

              All the best

               

              Jean LUCAS

               

               


              De : jrwatts4 <jrwatts@...>
              À : kepptheremins@yahoogroups.com
              Envoyé le : Mer 2 mars 2011, 3h 17min 37s
              Objet : [kepptheremins] Another Mark Keppinger Theremin is Born

               

              Well after a little more than a year of off-an-on progress I finally finished it and I'm very pleased with the result.  I posted a photo album of the finished Theremin in this group's Photos folder.  I believe this chassis set is the last of the original batch from Mark by way of Kyle.  For the group's reference, I posted two documents with chassis dimensions in this group's Files folder.

              I would like to thank Mark and Kyle for their generous guidance early on and to Phillip for making his very helpful experience available on his website.  I followed the J. Sparks schematics (Rev 7 – dated 12/20/2008) closely and made no electronic changes.  I'm very happy to report that it worked very well from the moment I first plugged it in.  No problems with the oscillators (knock on wood), they seem rock solid.  It sings beautifully.  The wave forms are clean and display similar to those on Phillip's website.  

              I did incorporate a few parts and layout enhancements partly based on comments of previous builders: 

              It was commented that the 3K resistor in the power supply can get hot so I installed a 50 watt with heat-sink mounted to the chassis.  As you might guess, it runs very cool.  In fact all the components run very cool (except the tubes of course).

              To make the oscillator trimmers more accessible, I mounted them upside-down on the terminal strip and drilled holes through the top of the chassis to make the adjustment.  I inserted a grommet in each hole to help guide the non-metallic screwdriver to the adjustment screw.  It works quite well.  

              In the pitch and tone oscillators, I installed a 500pf capacitor in each for Concert Tuning (that was as close to 430pf as I had).  I then piggy backed each capacitor with an additional a 200pf in the pitch oscillator and a 250pf in the tone oscillator.  Now I can easily experiment back and forth from Concert to Bass by just taking the piggy packed caps in and out of circuit.

              I crafted and applied decal labels to both chassis' to identify the controls and tubes.  I also included a decal indicating its a Mark Keppinger design.

              Until I have a cabinet constructed, the chassis's will be open and exposed.  To keep small grandchildren's hands out of bad places, I made black perforated aluminum covers that completely cover the bottom and sides of each chassis.  The pattern of 3/16" perforations on 1/4" centers allow more than sufficient ventilation.  The covers aren't shown in the photos.

              The wiring is cloth reproduction wire from Radio Daze.  The chassis's are painted with Hammer-tone Copper.

              Part of the delay in getting the build done was first making a coil winder (reference photo in the gallery).  I used a motor drive using a motor with a gear reduction to 20 rpm and providing sufficient torque (purchased on Antique Radio Forums).  I utilized an inexpensive belt and pulleys (available on Amazon) to have the ability to adjust the speed if needed.  I use a digital counter I found on Ebay.  The coil winder and motor drive worked very well and efficiently – I was able to wind all the coils in just a couple hours.  

              My next project is to make the antennas.  I currently have a Mickey Mouse version that I fashioned from 14 gauge electrical ground wire.  It works for the moment.  I have read various posts regarding making a reproduction RCA antenna – If anyone has a relatively easy approach to this or pitfalls I should avoid please let me know.  

              I will also tackle making a cabinet.  I'm considering incorporating a 10" speaker but also trying to keep the design suggestive of the RCA Theremin – not sure yet how to accomplish both.

              Guidance needed:  I need some perspectives in adjusting the various trimmers, etc.  I've found they interact enough that I'm not sure if any of my adjustments are optimal or that I'm converging on the most accurate overall adjustment.  I would appreciate any insights – ideally if you have a tried and true procedure to methodically or iteratively accomplish this please let me know.  Also what tests or symptoms have you found that indicate misalignment?

              Regards,

              Richard Watts

               


            • Mark Keppinger
              Jean; I would recommend solid (not tubing) brass. 1/4 can be formed by hand for the volume loop, but 3/8 is going to be fairly difficult. I did try making a
              Message 6 of 9 , Mar 3, 2011
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                Jean;
                 
                I would recommend solid (not tubing) brass. 1/4" can be formed by hand for the volume loop, but 3/8" is going to be fairly difficult. I did try making a 'bending jig', but the one that gave me the shape I wanted also scarred the metal, which is why I went ahead and bent them by hand, which wasn't as easy as it sounds.
                 
                Mark
                ----- Original Message -----
                Sent: Thursday, March 03, 2011 7:49 AM
                Subject: Re : [kepptheremins] Another Mark Keppinger Theremin is Born

                Richard,

                thanks for your answer.
                Concerning the antennas, you may know that Mike Buffington has built several RCA reproduction antenna sets, as you can see here:RCA Theremin Replica Antenna Construction 
                Maybe could he give you some tips ? His antennas seem to be very well built.

                Personnally, I was planning to use brass or copper rod that I would thread, which eliminates the need for a lathe, like on the "original" Keppinger theremins.

                all the best

                Jean



                De : Richard Watts <jrwatts@...>
                À : kepptheremins@yahoogroups.com
                Envoyé le : Mer 2 mars 2011, 20h 31min 05s
                Objet : RE: [kepptheremins] Another Mark Keppinger Theremin is Born

                 

                Mark and Jean, thank you for the kind words.

                 

                Jean the octal plug is vintage 1940s/50s and is made with a groove around the circumference to hold the snap on cap.  The cap didn’t have a hole for the cable so I had to drill it and insert a grommet.  I found the plug and cap at a radio club swap meet for $1.

                 

                Regards,

                 

                Richard

                 

                From: kepptheremins@yahoogroups.com [mailto:kepptheremins@yahoogroups.com] On Behalf Of Jean Lucas
                Sent: Wednesday, March 02, 2011 11:01 AM
                To: kepptheremins@yahoogroups.com
                Subject: Re : [kepptheremins] Another Mark Keppinger Theremin is Born

                 

                Hi Richard,

                Congratulations for your work! The wiring looks perfect, and your coil winder seems great too !

                I have a question about the octal plug you use : I was planning to use a tube base for my (future) Keppinger Theremin building, but it's not very satisfactory because it's open. On the contrary, your plug is closed. Did you build it from a "standart" tube base or did you find another kind of octal plug ? If yes, could you tell me where ?

                All the best

                 

                Jean LUCAS

                 

                 


                De : jrwatts4 <jrwatts@...>
                À : kepptheremins@yahoogroups.com
                Envoyé le : Mer 2 mars 2011, 3h 17min 37s
                Objet : [kepptheremins] Another Mark Keppinger Theremin is Born

                 

                Well after a little more than a year of off-an-on progress I finally finished it and I'm very pleased with the result.  I posted a photo album of the finished Theremin in this group's Photos folder.  I believe this chassis set is the last of the original batch from Mark by way of Kyle.  For the group's reference, I posted two documents with chassis dimensions in this group's Files folder.

                I would like to thank Mark and Kyle for their generous guidance early on and to Phillip for making his very helpful experience available on his website.  I followed the J. Sparks schematics (Rev 7 – dated 12/20/2008) closely and made no electronic changes.  I'm very happy to report that it worked very well from the moment I first plugged it in.  No problems with the oscillators (knock on wood), they seem rock solid.  It sings beautifully.  The wave forms are clean and display similar to those on Phillip's website.  

                I did incorporate a few parts and layout enhancements partly based on comments of previous builders: 

                It was commented that the 3K resistor in the power supply can get hot so I installed a 50 watt with heat-sink mounted to the chassis.  As you might guess, it runs very cool.  In fact all the components run very cool (except the tubes of course).

                To make the oscillator trimmers more accessible, I mounted them upside-down on the terminal strip and drilled holes through the top of the chassis to make the adjustment.  I inserted a grommet in each hole to help guide the non-metallic screwdriver to the adjustment screw.  It works quite well.  

                In the pitch and tone oscillators, I installed a 500pf capacitor in each for Concert Tuning (that was as close to 430pf as I had).  I then piggy backed each capacitor with an additional a 200pf in the pitch oscillator and a 250pf in the tone oscillator.  Now I can easily experiment back and forth from Concert to Bass by just taking the piggy packed caps in and out of circuit.

                I crafted and applied decal labels to both chassis' to identify the controls and tubes.  I also included a decal indicating its a Mark Keppinger design.

                Until I have a cabinet constructed, the chassis's will be open and exposed.  To keep small grandchildren's hands out of bad places, I made black perforated aluminum covers that completely cover the bottom and sides of each chassis.  The pattern of 3/16" perforations on 1/4" centers allow more than sufficient ventilation.  The covers aren't shown in the photos.

                The wiring is cloth reproduction wire from Radio Daze.  The chassis's are painted with Hammer-tone Copper.

                Part of the delay in getting the build done was first making a coil winder (reference photo in the gallery).  I used a motor drive using a motor with a gear reduction to 20 rpm and providing sufficient torque (purchased on Antique Radio Forums).  I utilized an inexpensive belt and pulleys (available on Amazon) to have the ability to adjust the speed if needed.  I use a digital counter I found on Ebay.  The coil winder and motor drive worked very well and efficiently – I was able to wind all the coils in just a couple hours.  

                My next project is to make the antennas.  I currently have a Mickey Mouse version that I fashioned from 14 gauge electrical ground wire.  It works for the moment.  I have read various posts regarding making a reproduction RCA antenna – If anyone has a relatively easy approach to this or pitfalls I should avoid please let me know.  

                I will also tackle making a cabinet.  I'm considering incorporating a 10" speaker but also trying to keep the design suggestive of the RCA Theremin – not sure yet how to accomplish both.

                Guidance needed:  I need some perspectives in adjusting the various trimmers, etc.  I've found they interact enough that I'm not sure if any of my adjustments are optimal or that I'm converging on the most accurate overall adjustment.  I would appreciate any insights – ideally if you have a tried and true procedure to methodically or iteratively accomplish this please let me know.  Also what tests or symptoms have you found that indicate misalignment?

                Regards,

                Richard Watts

                 




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              • Jean Lucas
                Mark, infact, I was planning to use 8mm solid copper (rather than brass), because I know someone who can give me the necessary length of it. Moreover, copper
                Message 7 of 9 , Mar 3, 2011
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                  Mark,

                  infact, I was planning to use 8mm solid copper (rather than brass), because I know someone who can give me the necessary length of it. Moreover, copper should be easier to work with and conducts electricity better (this difference may not be so important in this very case). I was thinking to something similar to what can be seen on Mike Buffington's page to bend the rod. heating it should make the things easier too I think.

                  I'll then try to find someone who can electro-plate the antennas. Nickel should be right.

                  By the way, I'm a student in science and I have chosen the theremin as a subject for my oral examination at the end of the year. I'll focus on how the wave is produed, heterodyne and so forth... I use your schematic as the main source.

                  All the best
                   
                  Jean



                  De : Mark Keppinger <mkepp@...>
                  À : kepptheremins@yahoogroups.com
                  Envoyé le : Jeu 3 mars 2011, 17h 01min 12s
                  Objet : Re: [kepptheremins] Another Mark Keppinger Theremin is Born

                   

                  

                  Jean;
                   
                  I would recommend solid (not tubing) brass. 1/4" can be formed by hand for the volume loop, but 3/8" is going to be fairly difficult. I did try making a 'bending jig', but the one that gave me the shape I wanted also scarred the metal, which is why I went ahead and bent them by hand, which wasn't as easy as it sounds.
                   
                  Mark
                  ----- Original Message -----
                  Sent: Thursday, March 03, 2011 7:49 AM
                  Subject: Re : [kepptheremins] Another Mark Keppinger Theremin is Born

                  Richard,

                  thanks for your answer.
                  Concerning the antennas, you may know that Mike Buffington has built several RCA reproduction antenna sets, as you can see here:RCA Theremin Replica Antenna Construction 
                  Maybe could he give you some tips ? His antennas seem to be very well built.

                  Personnally, I was planning to use brass or copper rod that I would thread, which eliminates the need for a lathe, like on the "original" Keppinger theremins.

                  all the best

                  Jean



                  De : Richard Watts <jrwatts@...>
                  À : kepptheremins@yahoogroups.com
                  Envoyé le : Mer 2 mars 2011, 20h 31min 05s
                  Objet : RE: [kepptheremins] Another Mark Keppinger Theremin is Born

                   

                  Mark and Jean, thank you for the kind words.

                   

                  Jean the octal plug is vintage 1940s/50s and is made with a groove around the circumference to hold the snap on cap.  The cap didn’t have a hole for the cable so I had to drill it and insert a grommet.  I found the plug and cap at a radio club swap meet for $1.

                   

                  Regards,

                   

                  Richard

                   

                  From: kepptheremins@yahoogroups.com [mailto:kepptheremins@yahoogroups.com] On Behalf Of Jean Lucas
                  Sent: Wednesday, March 02, 2011 11:01 AM
                  To: kepptheremins@yahoogroups.com
                  Subject: Re : [kepptheremins] Another Mark Keppinger Theremin is Born

                   

                  Hi Richard,

                  Congratulations for your work! The wiring looks perfect, and your coil winder seems great too !

                  I have a question about the octal plug you use : I was planning to use a tube base for my (future) Keppinger Theremin building, but it's not very satisfactory because it's open. On the contrary, your plug is closed. Did you build it from a "standart" tube base or did you find another kind of octal plug ? If yes, could you tell me where ?

                  All the best

                   

                  Jean LUCAS

                   

                   


                  De : jrwatts4 <jrwatts@...>
                  À : kepptheremins@yahoogroups.com
                  Envoyé le : Mer 2 mars 2011, 3h 17min 37s
                  Objet : [kepptheremins] Another Mark Keppinger Theremin is Born

                   

                  Well after a little more than a year of off-an-on progress I finally finished it and I'm very pleased with the result.  I posted a photo album of the finished Theremin in this group's Photos folder.  I believe this chassis set is the last of the original batch from Mark by way of Kyle.  For the group's reference, I posted two documents with chassis dimensions in this group's Files folder.

                  I would like to thank Mark and Kyle for their generous guidance early on and to Phillip for making his very helpful experience available on his website.  I followed the J. Sparks schematics (Rev 7 – dated 12/20/2008) closely and made no electronic changes.  I'm very happy to report that it worked very well from the moment I first plugged it in.  No problems with the oscillators (knock on wood), they seem rock solid.  It sings beautifully.  The wave forms are clean and display similar to those on Phillip's website.  

                  I did incorporate a few parts and layout enhancements partly based on comments of previous builders: 

                  It was commented that the 3K resistor in the power supply can get hot so I installed a 50 watt with heat-sink mounted to the chassis.  As you might guess, it runs very cool.  In fact all the components run very cool (except the tubes of course).

                  To make the oscillator trimmers more accessible, I mounted them upside-down on the terminal strip and drilled holes through the top of the chassis to make the adjustment.  I inserted a grommet in each hole to help guide the non-metallic screwdriver to the adjustment screw.  It works quite well.  

                  In the pitch and tone oscillators, I installed a 500pf capacitor in each for Concert Tuning (that was as close to 430pf as I had).  I then piggy backed each capacitor with an additional a 200pf in the pitch oscillator and a 250pf in the tone oscillator.  Now I can easily experiment back and forth from Concert to Bass by just taking the piggy packed caps in and out of circuit.

                  I crafted and applied decal labels to both chassis' to identify the controls and tubes.  I also included a decal indicating its a Mark Keppinger design.

                  Until I have a cabinet constructed, the chassis's will be open and exposed.  To keep small grandchildren's hands out of bad places, I made black perforated aluminum covers that completely cover the bottom and sides of each chassis.  The pattern of 3/16" perforations on 1/4" centers allow more than sufficient ventilation.  The covers aren't shown in the photos.

                  The wiring is cloth reproduction wire from Radio Daze.  The chassis's are painted with Hammer-tone Copper.

                  Part of the delay in getting the build done was first making a coil winder (reference photo in the gallery).  I used a motor drive using a motor with a gear reduction to 20 rpm and providing sufficient torque (purchased on Antique Radio Forums).  I utilized an inexpensive belt and pulleys (available on Amazon) to have the ability to adjust the speed if needed.  I use a digital counter I found on Ebay.  The coil winder and motor drive worked very well and efficiently – I was able to wind all the coils in just a couple hours.  

                  My next project is to make the antennas.  I currently have a Mickey Mouse version that I fashioned from 14 gauge electrical ground wire.  It works for the moment.  I have read various posts regarding making a reproduction RCA antenna – If anyone has a relatively easy approach to this or pitfalls I should avoid please let me know.  

                  I will also tackle making a cabinet.  I'm considering incorporating a 10" speaker but also trying to keep the design suggestive of the RCA Theremin – not sure yet how to accomplish both.

                  Guidance needed:  I need some perspectives in adjusting the various trimmers, etc.  I've found they interact enough that I'm not sure if any of my adjustments are optimal or that I'm converging on the most accurate overall adjustment.  I would appreciate any insights – ideally if you have a tried and true procedure to methodically or iteratively accomplish this please let me know.  Also what tests or symptoms have you found that indicate misalignment?

                  Regards,

                  Richard Watts

                   




                  __________ NOD32 5923 (20110303) Information __________

                  This message was checked by NOD32 antivirus system.
                  http://www.eset.com

                • mkepp@hevanet.com
                  Jean; The conductivity will make no difference whatsoever. I *think* that brass is easier to nickel plate than copper. As I recall, it takes one more step
                  Message 8 of 9 , Mar 3, 2011
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                    Jean;

                    The conductivity will make no difference whatsoever. I *think* that brass
                    is easier to nickel plate than copper. As I recall, it takes one more
                    step (using something called "q-posite?) in the process. The only
                    diffence between nickel and chrome plating is an added step at the end
                    which applies the chrome (which is clear) plating over the nickel,
                    keeping it from tarnishing.

                    Good luck with your class project!

                    Mark

                    > Mark,
                    >
                    > infact, I was planning to use 8mm solid copper (rather than brass),
                    because> I
                    > know someone who can give me the necessary length of it. Moreover,
                    copper
                    s> hould
                    > be easier to work with and conducts electricity better (this difference
                    may> not
                    > be so important in this very case). I was thinking to something similar
                    to
                    > what
                    > can be seen on Mike Buffington's page to bend the rod. heating it should
                    ma> ke
                    > the things easier too I think.
                    >
                    > I'll then try to find someone who can electro-plate the antennas. Nickel
                    sh> ould
                    > be right.
                    >
                    > By the way, I'm a student in science and I have chosen the theremin as a
                    su> bject
                    > for my oral examination at the end of the year. I'll focus on how the
                    wave
                    > is
                    > produed, heterodyne and so forth... I use your schematic as the main
                    source> ..
                    >
                    > All the best
                    >
                    > Jean
                    >
                    >
                    >
                    >
                    >
                    > ________________________________
                    > De : Mark Keppinger <mkepp@...>
                    > �� : kepptheremins@yahoogroups.com
                    > Envoy�� le : Jeu 3 mars 2011, 17h 01min 12s
                    > Objet : Re: [kepptheremins] Another Mark Keppinger Theremin is Born
                    >
                    >
                    > ���
                    > Jean;
                    >
                    > I would recommend solid (not tubing) brass. 1/4" can be formed by hand
                    for> the
                    > volume loop, but 3/8" is going to be fairly difficult. I did try making
                    a>
                    > 'bending jig', but the one that gave me the shape I wanted also scarred
                    th> e
                    > metal, which is why I went ahead and bent them by hand, which wasn't as
                    ea> sy as
                    > it sounds.
                    >
                    > Mark
                    > ----- Original Message -----
                    > >From: Jean Lucas
                    > >To: kepptheremins@yahoogroups.com
                    > >Sent: Thursday, March 03, 2011 7:49 AM
                    > >Subject: Re : [kepptheremins] Another Mark Keppinger Theremin is
                    Born
                    > >
                    > >
                    > >Richard,
                    > >
                    > >thanks for your answer.
                    > >Concerning the antennas, you may know that Mike Buffington has built
                    se> veral
                    > >RCA reproduction antenna sets, as you can see here:RCA Theremin Replica
                    An> tenna
                    > >Construction
                    > >
                    > >Maybe could he give you some tips ? His antennas seem to be very
                    well
                    b> uilt.
                    > >
                    > >Personnally, I was planning to use brass or copper rod that I would
                    thr> ead,
                    > >which eliminates the need for a lathe, like on the "original"
                    Keppinger>
                    > >theremins.
                    > >
                    > >all the best
                    > >
                    > >Jean
                    > >
                    > >
                    > >
                    > >
                    > >
                    > >
                    > ________________________________
                    > De : Richard Watts <jrwatts@...>
                    > >�� : kepptheremins@yahoogroups.com
                    > >Envoy�� le : Mer 2 mars 2011, 20h 31min 05s
                    > >Objet : RE: [kepptheremins] Another Mark Keppinger Theremin is Born
                    > >
                    > >
                    > >Mark and Jean, thank you for the kind words.
                    > >
                    > >Jean the octal plug is vintage 1940s/50s and is made with a groove
                    arou> nd the
                    > >circumference to hold the snap on cap. The cap didn���t have a
                    h> ole for the
                    > >cable so I had to drill it and insert a grommet. I found the plug
                    and
                    > cap at
                    > >a radio club swap meet for $1.
                    > >
                    > >
                    > >Regards,
                    > >
                    > >Richard
                    > >
                    > >From:kepptheremins@yahoogroups.com
                    [mailto:kepptheremins@...> m] On
                    > >Behalf Of Jean Lucas
                    > >Sent: Wednesday, March 02, 2011 11:01 AM
                    > >To: kepptheremins@yahoogroups.com
                    > >Subject: Re : [kepptheremins] Another Mark Keppinger Theremin is
                    Born
                    > >
                    > >Hi Richard,
                    > >
                    > >Congratulations for your work! The wiring looks perfect, and your
                    coil
                    > winder
                    > >seems great too !
                    > >
                    > >I have a question about the octal plug you use : I was planning to
                    use
                    > a tube
                    > >base for my (future) Keppinger Theremin building, but it's not very
                    > >satisfactory because it's open. On the contrary, your plug is
                    closed.
                    D> id you
                    > >build it from a "standart" tube base or did you find another kind of
                    oc> tal
                    > >plug ? If yes, could you tell me where ?
                    > >
                    > >All the best
                    > >
                    > >Jean LUCAS
                    > >
                    > >
                    > >
                    > ________________________________
                    >
                    > >De :jrwatts4 <jrwatts@...>
                    > >�� : kepptheremins@yahoogroups.com
                    > >Envoy�� le : Mer 2 mars 2011, 3h 17min 37s
                    > >Objet : [kepptheremins] Another Mark Keppinger Theremin is Born
                    > >
                    > >
                    > >Well after a little more than a year of off-an-on progress I finally
                    fi> nished
                    > >it and I'm very pleased with the result. I posted a photo album of
                    the>
                    > >finished Theremin in this group's Photos folder. I believe this
                    chassi> s set
                    > >is the last of the original batch from Mark by way of Kyle. For the
                    gr> oup's
                    > >reference, I posted two documents with chassis dimensions in this
                    group> 's
                    > >Files folder.
                    > >
                    > >
                    > >I would like to thank Mark and Kyle for their generous guidance
                    early
                    o> n and
                    > >to Phillip for making his very helpful experience available on his
                    webs> ite.
                    > >I followed the J. Sparks schematics (Rev 7 ��� dated 12/20/2008)
                    > closely and
                    > >made no electronic changes. I'm very happy to report that it worked
                    ve> ry
                    > >well from the moment I first plugged it in. No problems with the
                    oscil> lators
                    > >(knock on wood), they seem rock solid. It sings beautifully. The
                    wave> forms
                    > >are clean and display similar to those on Phillip's website.
                    > >
                    > >I did incorporate a few parts and layout enhancements partly based
                    on
                    > >comments of previous builders:
                    > >
                    > >It was commented that the 3K resistor in the power supply can get
                    hot> so I
                    > >installed a 50 watt with heat-sink mounted to the chassis. As you
                    mi> ght
                    > >guess, it runs very cool. In fact all the components run very
                    cool
                    (> except
                    > >the tubes of course).
                    > >>
                    > >>To make the oscillator trimmers more accessible, I mounted them
                    upsi> de-down
                    > >>on the terminal strip and drilled holes through the top of the
                    chass> is to
                    > >>make the adjustment. I inserted a grommet in each hole to help
                    guid> e the
                    > >>non-metallic screwdriver to the adjustment screw. It works quite
                    we> ll.
                    > >>
                    > >>
                    > >>In the pitch and tone oscillators, I installed a 500pf capacitor
                    in
                    > each
                    > >>for Concert Tuning (that was as close to 430pf as I had). I then
                    pi> ggy
                    > >>backed each capacitor with an additional a 200pf in the pitch
                    oscill> ator
                    > >>and a 250pf in the tone oscillator. Now I can easily experiment
                    bac> k and
                    > >>forth from Concert to Bass by just taking the piggy packed caps
                    in
                    a> nd out
                    > >>of circuit.
                    > >>
                    > >>I crafted and applied decal labels to both chassis' to identify
                    the>
                    > >>controls and tubes. I also included a decal indicating its a
                    Mark
                    > >>Keppinger design.
                    > >>
                    > >>Until I have a cabinet constructed, the chassis's will be open
                    and
                    > >>exposed. To keep small grandchildren's hands out of bad places,
                    I
                    m> ade
                    > >>black perforated aluminum covers that completely cover the bottom
                    an> d sides
                    > >>of each chassis. The pattern of 3/16" perforations on 1/4"
                    centers
                    > allow
                    > >>more than sufficient ventilation. The covers aren't shown in the
                    ph> otos.
                    > >>
                    > >>
                    > >>The wiring is cloth reproduction wire from Radio Daze. The
                    chassis'> s are
                    > >>painted with Hammer-tone Copper.
                    > Part of the delay in getting the build done was first making a coil
                    wind> er
                    > (reference photo in the gallery). I used a motor drive using a motor
                    wi> th a
                    > gear reduction to 20 rpm and providing sufficient torque (purchased
                    on
                    > Antique Radio Forums). I utilized an inexpensive belt and pulleys
                    (avai> lable
                    > on Amazon) to have the ability to adjust the speed if needed. I use
                    a
                    > digital counter I found on Ebay. The coil winder and motor drive
                    worked> very
                    > well and efficiently ��� I was able to wind all the coils in just
                    > a couple
                    > hours.
                    >
                    > My next project is to make the antennas. I currently have a Mickey
                    Mous> e
                    > version that I fashioned from 14 gauge electrical ground wire. It
                    works> for
                    > the moment. I have read various posts regarding making a
                    reproduction
                    R> CA
                    > antenna ��� If anyone has a relatively easy approach to this or
                    pi> tfalls I
                    > should avoid please let me know.
                    >
                    > I will also tackle making a cabinet. I'm considering incorporating a
                    10> "
                    > speaker but also trying to keep the design suggestive of the RCA
                    Theremi> n ���
                    > not sure yet how to accomplish both.
                    >
                    > Guidance needed: I need some perspectives in adjusting the various
                    trim> mers,
                    > etc. I've found they interact enough that I'm not sure if any of my
                    > adjustments are optimal or that I'm converging on the most accurate
                    over> all
                    > adjustment. I would appreciate any insights ��� ideally if you
                    ha> ve a tried
                    > and true procedure to methodically or iteratively accomplish this
                    please> let
                    > me know. Also what tests or symptoms have you found that indicate
                    > misalignment?
                    >
                    >
                    > Regards,
                    >
                    > Richard Watts
                    > >
                    > >
                    > >
                    > >__________ NOD32 5923 (20110303) Information __________
                    > >
                    > >This message was checked by NOD32 antivirus system.
                    > >http://www.eset.com
                    > >
                    >
                    >
                    >
                    >
                  • Chad W
                    ... Richard... An inspiration indeed. I enjoyed the detail in you post and perhaps I can incorporate some of that in my build. I am at the very beginning
                    Message 9 of 9 , Mar 6, 2011
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                      --- In kepptheremins@yahoogroups.com, "jrwatts4" <jrwatts@...> wrote:
                      > Well after a little more than a year of off-an-on progress I finally
                      > finished it and I'm very pleased with the result.

                      Richard...

                      An inspiration indeed. I enjoyed the detail in you post and perhaps I can incorporate some of that in my build.

                      I am at the very beginning stage. I am doing more reading than I am building. Just looked at your photos, and they look great!

                      Thanks so much for sharing.

                      jack
                      Portland Oregon
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