Vacuum tube
A vacuum tube, or radio tube, was a piece of electronics technology used on Earth in the 20th century.

When James T. Kirk asked Spock whether he could build some form of computer in 1930 to pinpoint Doctor McCoy's location and date of arrival in that year, Spock voiced his skepticism by answering "In this zinc-plated vacuum tubed culture?" ()

Iotian radios used vacuum tubes. ()

In a holoprogram set in 1944 France, Katrine ordered Mademoiselle de Neuf to visit a man named Goulot in a cottage outside Sainte Claire. He had a wine cellar full of vacuum tubes, including high-frequency oscillators. Katrine was willing to pay between 300 and 500 Francs to buy one, using it to increase the range of her radio. ()

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Communications technology