Crystal Sets

     The earliest of radio types was known as the "crystal set".  These were manufactured later on by various commercial manufacturers, but the earliest ones were made at home by individuals interested in seeing if they could pickup radio stations.  There was no power needed for these sets, as they used various mineral chips to "detect" radio signals.  If one built a good one, had a good sensitive set of headphones, had a long wire for an antenna and carefully tuned the set, one could hear radio signals.  One of the finest examples of a home made set is a set in our radio museum.  Not only is this one in exquisite condition but is the only one we have ever seen that used a micro-ammeter to measure incoming radio signals to help in finding the "sweet spot" or point of highest sensitivity on the crystal that was used to detect the signal.  Since these had no tubes, the audio was barely detectable under normal conditions but if one lived near a local radio station, the sound would be louder.