Winding the Coil

    Your form is a section of 3 1/8” O.D. cardboard mailing tube, cut to 3 inches long.  The winding guide file is Primaryandsecondarywindings.pdf.  The light gray strip should print out to 1 ¼ “ wide, and the dark gray strip should be 5/8” wide.  You will need one of each for each radio.  I printed two just to save paper for the fourth graders project.  If the widths are not accurate and you can’t adjust on your computer, then you can use a copier with a custom enlarger function. Or you can just eyeball it to compensate, by starting and ending your winding just inside or outside the gray area. Just try to center your winding over the gray area.

1. Glue the paper winding guide on the cardboard tube coil form.  Plan the paper alignment on the form so that the little squares are not located over a spiral seam in the cardboard.

2. Overlap the paper so all the lines are straight and the seam is almost invisible.  Note that there is an unprinted end of the paper; glue that part on the form first so that it gets covered up by the rest of the paper.

3. Use a push pin to punch four holes in the little squares.  The wire will fit through these holes.

4. Tie one end of 42 feet of #24 enamel wire to a fence.  Stretch the wire out its full length.  Walk away from the fence the entire length of the wire to make sure the wire is smooth, Remove any kinks. You will be winding the coil by walking toward the fence. Cut three 2” pieces of scotch tape to carry with you.

5. Thread six inches of the free end of the wire into the Start Here hole in the square marked “In.”  Immediately thread the wire back out of the “Out” square.  Fold it into the tube so it will be out of the way while you wind.

6. Wind the wire in the direction of the little arrow.  Do this by holding the tube where you can read the words right side up.  Gently pull the wire so it is barely taut. Start winding with a gentle tension on the wire, rolling the tube towards you as you slowly walk toward the fence.

7. You will be covering up the light gray portion with wire. To do this each winding must touch its neighbor closely.  Wind tightly. Don’t allow the windings to overlap or kink.  If you need help, just yell.

8. When you are at your last winding, just covering up the end of the light gray strip, put two pieces of tape across the winding to secure it.  When that is done, disconnect the wire from the fence and thread into and out of the holes like you did when you started the winding.  As before, the “In” hole square is clear, the “Out” hole square is black.

9. You should have about six inches of wire left over.  If you have more than twelve inches, wind one more turn before threading the wire. Otherwise clip the wire to six inches.

10. Prepare the second winding by gluing the narrower paper strip around the middle of the coil form, making sure it starts and ends where the first one did. Keep it aligned and centered on the first coil winding.

11. Punch four holes in the squares with the push pin.  This time you will be pushing the pin in between two wires on each side, so you will feel a little more resistance as the wires push apart.

12. Wind 21 feet, six inches of wire as you did the first winding.  Be sure to keep the loose ends of the windings within the center of the coil form so they are out of your way.  Use a single edge razor blade carefully to scrape off  1” of insulation all around the end of each wire. This finishes the coil.
 
 


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