The young gentlemen shown here are currently about 85 years old. They are shown in the July 1941 issue of Popular Mechanics demonstrating the operation of two of the seven crystal set circuits in the accompanying article.

The article noted that distant reception was possible under certain favorable and unusual conditions, but a crystal set was normally limited to a range of about ten miles. All of the circuits used a fixed detector. The simplest one was tuned by tapping the coil at various points. More complex circuits used various tricks to coax out as much signal as possible. The article stressed the importance of a long high antenna, and grounding to a cold water pipe.

Click Here For Today’s Ripley’s Believe It Or Not Cartoon