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The period from roughly 1912 to the late 1920s transformed amateur radio from a chaotic free-for-all of backyard spark stations into an organised, licensed, and technically sophisticated hobby. It was during these years that amateurs were first pushed to the margins of the radio spectrum — and then astonished the world by proving that the frequencies they had been given were far more useful than anyone had imagined. The story of early amateur radio is one of regulation, resilience, wartime service, and a discovery that changed the course of radio communication.
By 1910, interference between amateur, commercial, and military stations had become a serious problem, particularly in busy coastal areas. The sinking of the RMS Titanic in April 1912, while not directly caused by amateur interference, drew worldwide attention to the importance of reliable maritime radio communication and provided the political momentum for regulation.
In the United States, the Radio Act of 1912 was the first federal legislation to require licences for all radio transmitters. The act assigned amateur stations to wavelengths of 200 metres and shorter (frequencies of 1.5 MHz and above). At the time, these short wavelengths were believed to be nearly useless for long-distance communication — established wisdom held that only long wavelengths (low frequencies) could travel far. The 200-metre limit was, in effect, a way of keeping amateurs out of the "useful" part of the spectrum.
Similar restrictions were enacted in other countries. In the United Kingdom, the Wireless Telegraphy Act had already been in force since 1904, and amateur licences were issued under increasingly specific conditions. Canada, Australia, and other nations followed with their own regulatory frameworks, each reflecting the local balance of power between military, commercial, and amateur interests.
When the United States entered World War I in April 1917, the federal government ordered all amateur radio stations to shut down and dismantle their antennas. Similar shutdowns occurred in the United Kingdom, Canada, and other belligerent nations. Amateur operation was banned for the duration of the war.
The shutdown was a blow to the young hobby, but it was not a total loss. Many amateur operators enlisted or were recruited into military signal corps and naval communication roles, where their radio skills were put to immediate practical use. The war provided thousands of young operators with training, experience, and access to equipment far more sophisticated than anything they had at home. When the ban was lifted in late 1919, these veterans returned to amateur radio with new skills and new ambitions.
The American Radio Relay League (ARRL) was founded in 1914 by Hiram Percy Maxim (callsign 1WH, later W1AW) and Clarence Tuska. Maxim's original concept was a relay network — a chain of amateur stations across the country that could pass messages from point to point, since individual stations had limited range. The ARRL quickly became the primary organising body for amateur radio in the United States, publishing QST magazine (first issue December 1915), advocating for amateur interests before the government, and coordinating operating activities.
Other countries developed their own national societies. The Radio Society of Great Britain (RSGB) traces its origins to 1913. The Wireless Institute of Australia (WIA) was founded in 1910. These organisations played similar roles: representing amateurs to their governments, publishing technical journals, organising contests and events, and fostering a sense of community among operators who might otherwise have been isolated experimenters.
The most consequential technical achievement of early amateur radio was the discovery that short wavelengths — the very frequencies to which amateurs had been banished — were capable of long-distance communication far beyond what anyone had predicted.
In the early 1920s, amateurs began systematically exploring wavelengths shorter than 200 metres. The results were startling. In December 1921, American amateur Paul Godley (2ZE) travelled to Ardrossan, Scotland, with a sensitive receiver and successfully copied signals from over 30 American amateur stations transmitting on wavelengths around 200 metres. This was the first confirmed transatlantic reception of amateur signals, and it electrified the hobby.
The experiments continued and pushed to ever-shorter wavelengths. In November 1923, American amateurs Fred Schnell (1MO) and John Reinartz (1QP) established two-way transatlantic contact with French amateur Léon Deloy (8AB) on a wavelength of approximately 110 metres (about 2.7 MHz). This was the first confirmed two-way amateur transatlantic communication.
By 1924–1925, amateurs were working on wavelengths as short as 20 metres (14 MHz) and discovering that these frequencies could provide reliable communication over distances of thousands of kilometres with remarkably low power. The "useless" short waves turned out to be the key to worldwide radio communication. This discovery had enormous implications not just for amateur radio but for all of radio communication — commercial and military services quickly followed amateurs onto the shortwave bands.
The technical key to the shortwave breakthrough was the vacuum tube (thermionic valve). Lee De Forest's Audion triode, patented in 1906, could amplify weak signals and generate continuous radio-frequency oscillations. By the early 1920s, vacuum tubes had replaced spark-gap transmitters in most amateur stations, enabling cleaner signals, higher frequencies, and the transmission of voice as well as Morse code.
Amateur operators were enthusiastic adopters and improvers of vacuum tube technology. They designed and built their own transmitters and receivers using tubes that were becoming increasingly available and affordable. The shift from spark to vacuum tube was not just a technical upgrade — it changed the character of amateur radio from a noisy, broadband affair to a hobby capable of precision and finesse.
With vacuum tubes came continuous wave (CW) transmission — a clean, steady radio-frequency signal that could be keyed on and off to send Morse code. CW was far more efficient and occupied far less bandwidth than the broad, ragged pulses of a spark transmitter. CW became the dominant mode on the amateur bands and remains in widespread use today.
Vacuum tubes also enabled amplitude modulation (AM), allowing amateurs to transmit voice for the first time. AM phone operation began appearing on the amateur bands in the early 1920s and grew steadily. Voice communication attracted a new wave of operators to the hobby, though many old-timers initially regarded phone operation as inferior to the precision and skill of CW.
The explosive growth of both amateur and commercial radio in the 1920s — including the rise of broadcasting — created a crowded and often chaotic spectrum. The Radio Act of 1912 proved inadequate to manage the new landscape. In the United States, the Radio Act of 1927 created the Federal Radio Commission (FRC), which was given authority to allocate frequencies, assign callsigns, and regulate all radio services. The FRC was replaced in 1934 by the Federal Communications Commission (FCC), which continues to regulate amateur radio in the United States today.
The 1927 act and its international counterparts formalised the amateur radio bands — specific frequency allocations set aside for amateur use. These allocations, negotiated at international radio conferences, established the basic band structure that amateurs still use: 160 metres (1.8 MHz), 80 metres (3.5 MHz), 40 metres (7 MHz), 20 metres (14 MHz), and so on. See Licensing and Regulations for how this framework has evolved.
As amateur signals crossed national borders with ease, international coordination became essential. The International Amateur Radio Union (IARU) was founded in Paris in 1925, with representatives from national amateur radio societies in 25 countries. The IARU's mission was to represent amateur radio interests at international radio conferences and coordinate band plans and operating practices across borders.
The IARU's founding was a recognition that amateur radio was inherently international — a contact between operators in different countries was an everyday occurrence, and the hobby needed a unified voice in international spectrum negotiations. The IARU continues to serve this role today, representing amateur interests at the International Telecommunication Union (ITU) and coordinating with national societies worldwide.
By the late 1920s, amateur radio had been transformed. What began as a handful of spark-gap tinkerers had become an organised, licensed, international community of tens of thousands of operators equipped with vacuum tube transmitters and receivers, operating on allocated frequency bands, communicating across oceans and continents. The foundations had been laid for what would become the golden age of amateur radio — a period of explosive growth, technical innovation, and wartime service that would shape the hobby for generations. That story continues in The Golden Age of Ham Radio.
| Year | Event | Significance |
|---|---|---|
| 1912 | US Radio Act of 1912 | First amateur licensing; amateurs assigned to wavelengths below 200 m |
| 1914 | ARRL founded | First national amateur radio organisation in the US |
| 1915 | First issue of QST | ARRL's magazine becomes a hub for the amateur community |
| 1917–19 | Wartime shutdown | All amateur operation banned during World War I |
| 1921 | Transatlantic reception tests | American amateur signals received in Scotland |
| 1923 | First two-way transatlantic contact | Schnell/Reinartz (US) to Deloy (France) on ~110 m |
| 1924–25 | Shortwave exploration | Amateurs demonstrate reliable long-distance communication on 20–40 m |
| 1925 | IARU founded | International coordination of amateur radio begins |
| 1927 | US Radio Act of 1927 | Federal Radio Commission created; formal band allocations established |