The 807, a Vacuum Tube for the Ages

Eight decades on, this device still has a niche among ham radio enthusiasts and audiophiles

1 min read
Vintage announcement for RCA-807 radio tube
Photo: Randi Klett

In the 1930s, as the United States recovered from the Great Depression, most people couldn’t afford a new radio. Even so, the Radio Corporation of America earned a tidy profit on vacuum tubes like the 807, [pdf] introduced in 1937. The 807 proved especially popular with amateur radio operators, as evidenced by this ad from the March 1940 issue of QST, a ham-radio magazine. And in 1947, English engineer D.T.N. Williamson described the circuit for his eponymous high-fidelity audio amplifier [pdf], variations of which used the 807. Although RCA closed its electron tube operation in 1976, 807s are still made in Russia and China, and audiophiles continue to debate the technical and aesthetic qualities of 807s from different companies, eras, and countries.

About the Author

Alexander B. Magoun is an outreach historian at the IEEE History Center in Hoboken, N.J. 

This article originally appeared in print as “A Vacuum Tube for the Ages.”

Part of a continuing series looking at the story of technology as told through advertisements.

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The Scandalous History of the Last Rotor Cipher Machine

How this gadget figured in the shady Rubicon spy case

15 min read
The HX-63 cipher machine

The HX-63 cipher machine is an electromechanical, rotor-based system designed and built by Crypto AG.
The machine uses nine rotors [center right] to encrypt messages. A dual paper-tape printer is at the upper left.

PETER ADAMS

Growing up in New York City, I always wanted to be a spy. But when I graduated from college in January 1968, the Cold War and Vietnam War were raging, and spying seemed like a risky career choice. So I became an electrical engineer, working on real-time spectrum analyzers for a U.S. defense contractor.

In 1976, during a visit to the Polish Army Museum in Warsaw, I saw an Enigma, the famous German World War II cipher machine. I was fascinated. Some years later, I had the good fortune of visiting the huge headquarters of the cipher machine company Crypto AG (CAG), in Steinhausen, Switzerland, and befriending a high-level cryptographer there. My friend gave me an internal history of the company written by its founder, Boris Hagelin. It mentioned a 1963 cipher machine, the HX-63.

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