Crystal receiver set 11

Step 3     Making the coil

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The coil is wound around a 70 mm diameter PVC tube, the length of the tube is about 70 mm.
Saw some small slots in the side of the tube (indicated by the arrows), here you can hook on the coilwire.
Saw through the tube over its length, and fill this space with two matches.
Fix the matches with some tape on the inside of the tube.

Make a paper strip with 4 sections of 40x55 mm on it.
Do the strip around the tube, and fix it with a piece of tape.
Don't tape the strip onto the tube on places where later the coil is wound.

For the coil we need 8.6 meter enamelled copper wire with 0.8 mm thickness.
Hook the begin of the coilwire onto the slot in the tube.
Also fix the begin of the wire on the inside of the tube with some tape.

Wind 36 windings around the tube
Hook the end of the wire onto a slot in the tube, and fix the wire with some tape to the inner side of the tube.

Press the winding to each other, so all spacings disappear.
Do some tape over the windings to keep them in place.

Apply glue on the coil (not on the stick), right above the line on the paper.
Lay the stick on the glue, and fix it with  rubber bands.
Do this for all four sticks.

Use transparent 2-component glue.

Wait until the glue is hardened.
Remove the rubber bands, the tape and the matches.
Shift the tube out of the coil, and remove the paper out of the coil.
Turn the both ends of the wire one time around the stick at the bottom side of the coil, and apply some extra glue here.

Saw two sticks on length, somewhat longer then the coil.
The sticks at upper and lower side of the coil must not be shortened yet.

Apply some glue in the holes in the 9 mm sticks
Also apply some glue in the 9 mm holes in the bottom plate.
Place the coil as shown in this picture.
Wait until the glue is dry.

Saw of the ends of the sticks, which stick out of the 9 mm sticks.
Lacquer the sawed ends of the sticks with coloured lacquer, so the colour corresponds with the rest of the wood.

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