For the most part we think of portable radios as a post-World War II phenomenon. From the cheap plastic models of the 1950s to today’s elaborate Walkmans, they have been among the most visible examples of the electronics revolution. But portable radios did not start with the invention of the transistor; their history stretches back more than two decades earlier. The 1920s gave birth to the boom box, but the boom box boom quickly went bust.

During the teens point-to-point transmission (for ship-to-shore and military communication) was radio’s main application. Radio broadcasting as we know it began in 1920. For several years Frank Conrad, a Westinghouse engineer in Pittsburgh, had been playing records over the air for a few hours each Saturday night. He attracted quite a following. Eventually Westinghouse got the idea of using entertainment broadcasting to sell radios to the general public, instead of just hobbyists. Conrad, who had been working out of his garage, was invited to set up a station in a company building. Christened KDKA, it became the country’s first radio station dedicated to entertaining the public.

The idea spread quickly. By early 1923 there were more than five hundred radio stations in the United States licensed for entertainment broadcasting, stimulating the growth of a radio industry. Hundreds of radio manufacturers came and went by the end of the decade; only a few, such as RCA, Zenith, and Philco, would endure.

Because all radios in the early 1920s ran on batteries, they could be put in the car and taken along on automobile excursions, just like portable phonographs. Magazines showed sets being used on boats, camping trips, and picnics. Some firms promoted their sets as portables in 1921 and 1922; these were basically home models modified slightly for outdoor use. Besides being cumbersome, their main problem was that they used up battery power too quickly.

The key advance in portables came in 1922, when General Electric announced a new three-inch vacuum tube called the UV-199 that had a “low-drain” filament. It was considerably easier on batteries than the tubes then used in stationary home radios, whose filaments were powered by rechargeable lead-acid batteries. With the UV-199 a radio could play two hours a day for three weeks before its filament batteries wore out, making portables much less tiresome to use. The announcement stimulated a flurry of activity among radio makers.

Between late 1923 and 1926 dozens of companies released true portable radios, designed for the purpose from the start. To celebrate the portable’s coming of age, Radio News published its “First Annual Portable Radio Set Directory” in August 1925. It was compiled by Hugo Gernsback, the sciencefiction writer who would found Amazing Stories the following year. The directory listed twenty-two models from sixteen manufacturers. They were mostly big and expensive, but enthusiasts expected that as time went on, tubes would get smaller, batteries would get lighter, and mass production would cause prices to fall. Yet the First Annual Portable Radio Set Directory turned out to be the last; by 1926 the boom was over.

In believing that portable radios could play the same role in outings as portable phonographs, radio manufacturers were mistaken for several reasons. First of all, most radio stations in the 1920s still had transmitters of five hundred watts or less, so reception in the country was erratic. Second, the modern idea of stations with characteristic identities and formats had not yet developed. Broadcasters mixed music, sports, scientific lectures, and religious services in seemingly random fashion. A young man looking for mood music while pitching pastoral woo might have to settle for a quack hawking goatgland transplants to restore virility. Finally, there was the price. A decent self-contained portable radio went for at least $150, more than an average month’s salary at the time. Phonographs, by contrast, could be had for less than $50; they worked anywhere, and users could play whatever they wished.

The next wave of portables began in the late 1930s, and eventually they became commonplace. Still, the portable radio could have survived as a luxury item following its abortive 1920s launch; there was nothing technologically unfeasible about it. With the fragmented broadcasting business of the time, however, all too often there was nothing for upscale Americans to listen to on their fancy new toys.