Dave's Has Nothing To Hide! — #43 Crystal Set
Hi Crystal set fans! I'm not keeping up my torrid 2003 building frenzy this year, but I hope you like the radios that I am building. This radio brings me back to my roots of my first set. Little did I know then that I would be building nearly four dozen sets, so far.
This easy to build set is constructed in the same box as my first one, except this box is clear. A fellow crystal set builder kindly made me a very nice looking plastic spider coil form. This looked so nice, I felt I had to show it off in a special way. Hence, the clear plastic box.
The box is a Hammond 1591ETCL. This box is 7.5x4.3x2.2 inches (191x110x57 mm) large. This is plenty of room to mount the 4 inch diameter spider coil plus the two variable capacitors and the rest of the components.
Since this is a clear box, the inside have to look as nice as the outside. I used some 14 gauge tinned copper wire with ring terminals to make the antenna - ground connections. The connections to the headphones are made with 18 gauge bare tinned copper wire. The rest of the components are mounted on a 3 terminal solder lug mounted on the back of the detector tuning capacitor. Brass hardware with thumb nuts round out this nice looking radio.
The coil is wound with 165/46 litz wire. 54 turns (about 35 feet (10.5m)) is needed for this coil. The inductance measures 158 µH. The hub diameter is 1 inch (25mm) and the outside is 4 inches (100mm). After winding the coil, the wires should be adjusted for even spacing. This makes the coil look nicer.
The labels are made with a Brother P-touch machine that is connected to my computer. I used black letters on a clear background so that the labels would blend in with the clear plastic.
The circuit diagram shows the wiring. This radio was built to be used with an audio matching transformer and my sound powered headphones. A crystal earphone can be used by placing a 47 k ohm resistor across the headphone terminals. If you are using a transformer, leave out the resistor. That's about all I can tell you about my #43 radio. I hope you enjoy building yours as I have mine.
73 and good crystal DX. Dave - N2DS