85 years ago this month, the May 1932 issue of Shortwave Craft magazine showed the plans for this simple one-tube converter to listen in to police calls, or, as the magazine called it, a “Thrill Box.”

The one-tube converter covered the frequencies just above the broadcast band to allow reception of police dispatchers.  According to the magazine, they were then using wavelengths of 121-125 and 178-180 meters (1.67-1.71 MHz and 2.4-2.48 MHz).  The set used an intermediate frequency in the broadcast band, allowing the standard broadcast set to listen in on the thrills.