1920s Radio Electronics: The Birth of Broadcasting
Introduction
The 1920s marked a pivotal era in radio technology development, transforming wireless communication from a military and commercial tool into an entertainment medium that revolutionized American society. This decade saw rapid advancements in radio electronics, from rudimentary crystal sets to sophisticated vacuum tube receivers, while establishing the foundation for modern broadcasting that would shape media consumption for generations to come.
Early Radio Development and Broadcasting Origins
The Birth of Commercial Broadcasting
The modern era of radio broadcasting began in 1920 when the Westinghouse Company received the first commercial radio license, creating station KDKA in Pittsburgh. On November 2, 1920, KDKA made history by broadcasting the Harding-Cox presidential election returns, marking the first scheduled public broadcast. This watershed moment launched radio’s transition from point-to-point communication to public broadcasting.
The growth of radio throughout the decade was remarkable. In 1921, there were only 5 radio stations in the United States, but by the end of the 1920s, that number had exploded to 606 stations. This rapid expansion reflected both technological advancements and growing public enthusiasm for this revolutionary medium FamilySearch.
Early 1920s radio with horn speaker [Wikimedia Commons]
Crystal Radio Technology
The First Consumer Radio
The crystal radio receiver was the first widely accessible radio technology for the general public. These simple devices required no external power source, operating solely on the energy captured from radio waves themselves.
How Crystal Radios Worked
The basic components of a crystal radio included:
- An antenna to capture radio signals
- A tuned circuit (coil and sometimes a capacitor) to select frequencies
- A crystal detector to demodulate the radio signal
- Earphones to convert the signal to sound
The heart of the crystal radio was the detector, typically a galena (lead sulfide) crystal contacted by a thin wire known as a “cat’s whisker.” This primitive semiconductor junction acted as a diode, converting radio frequency signals into audible sounds.
Homebrew 1920s Crystal Set [Ohio University]
Crystal sets were most popular in the early 1920s when radio broadcasting first began. They could receive relatively strong local AM broadcasts but had limited selectivity and could not amplify signals. Despite these limitations, crystal radios were instrumental in introducing radio to millions of people due to their low cost and simple operation.
Advertisements from the period show families gathered around crystal radios, highlighting its role in bringing families together for entertainment.
Decline of Crystal Sets
Around 1920, crystal sets began to be superseded by vacuum tube receivers that offered signal amplification and better performance. However, crystal radios continued to be built by hobbyists, youth groups, and Boy Scouts as educational devices, and enjoyed continued popularity during the Depression due to their affordability.
Vacuum Tube Technology and Circuit Development
The Revolution of Vacuum Tubes
The development of vacuum tube technology in the early 20th century revolutionized radio electronics. Vacuum tubes could amplify weak signals, making it possible to receive distant stations and power loudspeakers for the first time.
Key Vacuum Tube Developments
Vacuum tube radio equipment replaced primitive spark-gap systems on most merchant ships and in homes by the late 1920s. These devices could send and receive signals virtually worldwide by using high-frequency or “short-wave” bands.
During the mid-1920s, the Westinghouse company acquired Lee de Forest’s and Edwin Armstrong’s patents, which were critical to vacuum tube development. Amplifying vacuum tubes dramatically improved radio receiver performance, enabling:
- Greater reception distance
- Improved selectivity
- The ability to power loudspeakers instead of just headphones
- More sophisticated circuit designs
Vintage Homebrew Superheterodyne Radio with 8 Vacuum Tubes, circa 1920s [Wikimedia Commons]
Popular 1920s Radio Circuits
Several radio circuit designs emerged during the 1920s, each with its own advantages:
TRF (Tuned Radio Frequency)
These receivers used multiple tuned stages to increase sensitivity and selectivity. Each stage required its own tuning control, making early models complex to operate until ganged capacitors were developed.
Regenerative Circuits
Invented by Edwin Armstrong in 1912, regenerative receivers used positive feedback to increase amplification. They were efficient but prone to producing unwanted oscillations that could interfere with other receivers.
The Superheterodyne Revolution
The most significant circuit innovation of the 1920s was the superheterodyne receiver, also invented by Edwin Armstrong. This design converted incoming radio signals to a lower intermediate frequency (IF) where they could be more efficiently filtered and amplified.
Major Edwin H. Armstrong invented the superheterodyne (nicknamed “superhet”) in the closing days of World War I. After the war, Armstrong sold the patent rights to the Radio Corporation of America (RCA). He called it the “Rolls Royce method of reception” because of the large number of tubes required and the resultant complexity and cost.
The superhet had significant advantages:
- Superior selectivity (ability to separate stations)
- Greater sensitivity
- More stable operation
- Better audio quality
RCA restricted licensing for superheterodyne manufacturing to just a few companies, but hobbyists created their own superhets from kits or individual parts. As transistors started becoming available in the 1950s, vacuum tubes gradually became obsolete.
Major Radio Manufacturers
Industry Leaders
The 1920s saw numerous companies enter the radio manufacturing business as demand for receivers soared. Some of the most significant manufacturers included:
RCA (Radio Corporation of America)
In the early 1920s, RCA became a dominant force in the radio industry as a major manufacturer of radio receivers and the exclusive producer of vacuum tubes under their “Radiotron” brand. Their popular Radiola series included models like the Radiola III (1924) priced at $24.50, which sold in the thousands, and the more sophisticated Radiola 18 and Radiola 60.
Vintage All-American/Mohawk Battery Powered Radio from the 1920s [Flickr]
Westinghouse
Westinghouse not only pioneered broadcasting with KDKA but also became a leading radio manufacturer. The company began advertising and selling radios to the public, helping to make radio a common household appliance.
Other Notable Manufacturers
- Atwater Kent
- Crosley
- Freed-Eisemann
- Grebe
- A-C Dayton
- Kellogg
- Zenith
- Federal
- Magnavox
Alan Douglas documented nearly 150 radio manufacturers in his comprehensive volumes “Radio Manufacturers of the 1920s,” demonstrating the explosive growth of this new industry.
The Evolution of Radio Receivers
From Battery Sets to Plug-In Models
Early 1920s radio receivers required multiple batteries:
- “A” batteries (typically 6 volts) to heat the tube filaments
- “B” batteries (45-90 volts) for plate voltage
- Sometimes “C” batteries for grid bias
These battery-powered radios were cumbersome and expensive to maintain. By the late 1920s, plug-in radios powered by household electricity began to replace battery sets, making radio ownership more convenient and affordable.
Technical Improvements
Throughout the decade, radio technology underwent continuous refinement:
- Tuning systems evolved from multiple dials to single-dial control with ganged capacitors
- Cabinet design shifted from exposed components to furniture-style consoles
- Speaker technology advanced from horn speakers to more efficient cone speakers
- Power supplies progressed from batteries to AC power
Impact on Society and Culture
The Radio Boom
Radio quickly became a cultural phenomenon. By the mid-1920s, radio ownership had spread rapidly:
- In 1922, there were fewer than 60,000 households with radios
- By 1925, that number had grown to 2.5 million
- By the end of the decade, over 10 million American households owned radios
Cultural Significance
Radio in the 1920s transformed American society by:
- Creating a shared national culture through broadcasts heard simultaneously across the country
- Introducing new forms of entertainment and information dissemination
- Establishing the first electronic mass medium with unprecedented reach
- Connecting rural and isolated communities to national events and culture
As one commentator noted: “Radio is virtually useless,” while another countered that it was “a Tremendous Contribution” and “the only means of instantaneous communication yet devised by man.” Arguments over radio’s value and future reflected the transformative impact this new technology was having on society.
Building and Owning Radios
The DIY Radio Movement
In 1921, factory-made radios were expensive luxury items. To make radio more accessible, newspapers and magazines published articles on building crystal radios with common household items. Many homemade radios used oatmeal boxes as a foundation for winding tuning coils, earning them the nickname “oatmeal box radios.”
The United States Bureau of Standards released publications in 1922 titled “Construction and Operation of a Simple Homemade Radio Receiving Outfit” and “Construction and Operation of a Two-Circuit Radio Receiving Equipment With Crystal Detector,” which further fueled the DIY radio movement.
Radio as Home Entertainment
As the decade progressed, radio evolved from a technical curiosity to an essential home entertainment device. Programming diversified to include:
- News broadcasts
- Musical performances
- Comedic sketches
- Sports events
- Farming and agricultural updates
- Children’s bedtime stories
- Weather reports
WLS Chicago, created in 1924 by Sears Roebuck & Co., offered a weekly variety program called the WLS Showboat, the “Floating Palace of Wonder.” Listeners would “travel” along American rivers on the Showboat and enjoy songs and humorous entertainment.
Technical Innovations and Challenges
Overcoming Technical Limitations
Engineers during the 1920s had to overcome significant technical challenges:
- RF Amplification – Early vacuum tubes had difficulty amplifying radio frequency signals due to internal capacitance. This was eventually solved through improved tube designs.
- Selectivity – As the number of stations increased, the ability to separate stations became crucial. The superheterodyne circuit was the ultimate solution to this challenge.
- Power Supplies – Converting household AC power to the DC voltages needed by radio tubes required the development of reliable rectifiers and filter circuits.
- Audio Quality – Improving audio fidelity was an ongoing challenge, with advancements in loudspeaker design and audio amplification circuits.
- Ease of Use – Simplifying operation from multiple tuning dials to single-control tuning made radios more user-friendly.
Conclusion
The 1920s represent the transformative decade when radio evolved from an experimental technology into a mainstream medium that permanently altered how people received information and entertainment. The progression from crystal sets to sophisticated vacuum tube receivers paralleled the evolution from amateur wireless telegraphy to professional broadcasting networks.
Technical innovations in vacuum tubes, circuit design, and manufacturing techniques established the foundation for electronic communication that would eventually lead to television, digital broadcasting, and modern wireless technologies. The radio revolution of the 1920s was not merely a technical achievement but a social revolution that connected Americans in unprecedented ways, creating the first truly national media experience.
The legacy of 1920s radio electronics continues today in modern broadcasting and in the principles that underpin all forms of electronic communication. The decade represents a pivotal moment when technology transformed from novelty to necessity, forever changing the American cultural landscape.
References
- Tech Wholesale, “History of the Radio,” https://techwholesale.com/history-of-the-radio.html
- FamilySearch, “Radio and Music in the 1920s United States,” https://www.familysearch.org/en/blog/1920s-radio-music-america
- PBS, “The Development of Radio,” https://www.pbs.org/wgbh/americanexperience/features/rescue-development-radio/
- Alan Douglas, “Radio Manufacturers of the 1920’s”
- Wikipedia, “Crystal Radio,” https://en.wikipedia.org/wiki/Crystal_radio
- Wikipedia, “Superheterodyne Receiver,” https://en.wikipedia.org/wiki/Superheterodyne_receiver
- Electronics Notes, “Superhet Radio History: Superheterodyne,” https://www.electronics-notes.com/articles/history/radio-receivers/superheterodyne-radio-receiver.php
- Duane Bylund, “1920s Superheterodynes,” https://www.duanesradios.info/
- American Class, “Radio, America in the 1920s,” https://americainclass.org/sources/becomingmodern/machine/text5/text5.htm
- Vermont Historical Society, “Early Days of Radio, 1920,” https://vermonthistory.org/early-days-of-radio-1920