Vectronics VEC-121K - Manual (Page 15)

VEC-121K Owner's Manual Crystal Radio Set Kit
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windings using the dispenser tip. Draw a very light bead of adhesive across
the full width of the winding. Very little adhesive is needed for these tasks!
Let the coil sit until the contact cement has fully cured! (You may use the
glue sold for assembling plastic models for these tasks. Remember, it will
take several hours for the glue to harden.)
! Now, finish winding the tuning coil. It takes about 3 feet of wire to do four
full turns. It takes about 66 turns of wire to fully wind the coil over the 2.5”
coil span; so you will use about 52 feet of wire for the entire winding. Don’t
bother trying to count turns as you go. A few extra or missing turns will not
affect the performance of the crystal set. What is important is to have the
winding cover the full 2.5” inch span, without gaps.
! Unspool another 20 feet of 18 AWG enamel coated wire. Remove the
masking tape from the coil form. Continue winding until the 20 feet of wire
is used. Tape the new windings to hold them in place.
! Again, inspect the new windings you have just completed. Are they tightly
wound, and free of gaps between adjacent windings? Squeeze the newer
windings towards the starting windings to close up any gaps. When you’re
satisfied, use masking tape to secure the turns, and then fix the windings in
place using contact cement or model glue.
Important Note: As you continue adding windings, you will reach a point where
your left hand fingers will no longer reach inside of the PVC coil form. At this
point, you will need both hands on the form as you work, and you will be using
both thumbs to guide the wire and keep the proper tension.
! Continue by unspooling 20 foot lengths of wire at time, winding the coil
until you reach the "finish" point on the coil form. Securely tape the coil
windings, and glue the new windings in place.
! At the end of the winding, mark off an additional 16” of wire, and cut the
wire at this point.
! Insert the 16” inch wire tail into the “finish” wire hole in the PVC coil form.
Bring the wire back out through the adjacent hole and pull with enough
force so the wire is snug. Secure the end point of the winding with a very
small drop of contact cement.
! Fish the wire end for the starting point of the winding out of the form. Your
coil should now resemble the illustration below: