The Field Kit by Koma Electronik is an electronic musical instrument which includes a radio receiver, whose external antenna input is a 3-pin header socket.
This is a 3D-printable case for an accessory which converts that socket to two BNC jacks. Required additional components:
- 2 panel-mount BNC jacks, such as Amphenol 031-221-RFX.
- A length of 3-conductor ribbon cable and matching header pins and housing. These can be found sold as RC servo extension cables.
- Solder.
- Optional but recommended: about 25 mm of solid uninsulated wire.
- Glue and double-sided tape (see below).
This model is not particularly optimized; in particular, the case could use some strengthening ribs and the snap-fit does not hold very strongly. I glued mine shut after confirming it is working.
- Print the box. You will almost certainly need to tweak the dimensions and iterate to suit your printer and wire. Test fit to ensure that:
- The cable can fit through the opening for it.
- The “panel” snaps into the “shell” firmly enough and the tab engages.
- The cable is held in position, but not so tightly that the shell is excessively bent by the pressure.
- Push the cable into the hole on the panel. (If your cable is multicolored, consider which way around you want it.)
- Bend the BNC connectors' shield connection tags up so that they fit within the box and can be soldered without melting the plastic.
- Secure the BNC connectors with their nuts.
- Solder the connections.
- The wire which will go to the Field Kit's GND should be joined to the shield of both BNC jacks; a length of solid wire may make a convenient bus bar for this.
- The other two wires should go to the centers of the two BNC jacks; if you ensure the wires do not cross over each other then when in use they will be in the same order as the Field Kit's connection labels.
- Close the box and test it.
- Optional: Glue it shut with superglue unless you edited the model to improve the snap-fit.
- Optional: Stick it to the side of your Field Kit with a 3M Command adhesive strip. Add a rubber foot to support it against the insertion force of the BNC plug without scraping the table.
Copyright 2018 Kevin Reid kpreid@switchb.org.
This work is licensed under a Creative Commons Attribution 3.0 International License.