1920: The Joseph Horne department store in Pittsburgh advertises ready-made radio receivers that can pick up a local broadcast station. Commercial radio is just weeks away.

Frank Conrad was assistant chief engineer of the Westinghouse Electric Company in Pittsburgh. He’d been interested in radio since 1912. To settle a $5 bet (around $110 in today’s money) about the accuracy of his $12 watch, Conrad built a radio receiver to hear the time signals transmitted by the U.S. Naval Observatory.

Conrad won the bet, but that’s not the point. Notice that he had to build his own receiver. Just like the days of home-brew computers later in the 20th century, that’s what aficionados of the emerging technology had to do in those days.

If you didn’t want to start from scratch, you could — and this, too, should sound familiar — buy a kit with all the parts and all the instructions. They were advertised in magazines that appealed primarily to … guys. Science magazines, the Boy Scout Handbook, cheap fiction, detective rags, and the kind of stuff you’d find in the barber shop.

In any case, Conrad was on to bigger things than building a receiver. Like building a transmitter. Under license 8XK, he started broadcasting from the second floor of his garage in nearby Wilkinsburg in 1916.

In fact, Conrad was a pioneer in using the word broadcasting. It was borrowed from agriculture, where it means spreading seeds far and wide. Radio in those days was conceived mainly as a two-way point-to-point medium. The idea of using one radio transmitter to reach a broad audience equipped only with receivers was something new.

Conrad tested and tweaked his equipment for hours on end in his spare time. But his voice got tired of making constant announcements of his call letters and location, so he started playing gramophone records to give it a rest.

Sure enough, those with their own transmitters started radioing requests for specific music. Those who had only their own scratchy receivers phoned or wrote in. Conrad was radio’s first DJ, and he was building an audience.

Horne’s department store had something new in 1920: the first shipment of ready-to-use radio receivers. Nothing to build, just plug-and-play. The store placed an advertisement in the Pittsburgh Sun heralding the miracle that you could listen to music over the air:

Air concert picked up by radio here. The music was from a Victrola in the home of Frank Conrad. Mr. Conrad is a wireless enthusiast and puts on these wireless concerts periodically for the entertainment of many people in this district who have wireless sets. Amateur wireless sets are on sale here $10 and up.

The signal was building a demand for the hardware. The hardware was marketing itself with the signal.