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|Assuming you’ve used wood as the core, make supports for it
with the 1” by 1-1/2” tin-can strips folded lengthwise for stiffness. Mount the tuning coil and core as shown in the main
drawing. If you’ve used tubing as the core, simply lay it flat
and nail it in place.
THE SLIDER ARM. Bend the 5” by 3/8” metal strip as shown in the sketch. A thick piece of bare copper wire will have to be soldered to the underside of the front. This wire allows the arm to make contact with no more than one or two turns of wire on the coil. That’s important for good tuning. You can use a piece of magnet wire for this purpose if you scrape the clear insulating coating from it. Finish the slider by wrap- ping some tape around the front edge. The tape prevents your touching the bare metal, which could weaken the signals.
Assembling the Set
Refer once again to the main drawing, or to the circuit diagram if you prefer, and start putting the parts together. It doesn’t make any difference which way you insert the capacitor. The same goes for the crystal diode. If at all possible, make as manny connections as you can by soldering. Weak signals can be lost through poor connections.
When installing the slider, be certain the copper wire underneath touches the coil throughout the full swing of the arm. Also, take a piece of sandpaper and remove all the insulation from the top of the coil . . .right down to the bare metal. The slider must be able to make contact with each turn of wire on the coil.