Acorn tube

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Acorn tube

The acorn tube is a type of vacuum tube (or thermionic valve) that was developed in the late 1930s by the RCA Corporation. It is named for its distinctive shape, which resembles an acorn. Acorn tubes were designed to operate at very high frequencies, making them suitable for use in radio and radar applications during World War II.

Design and Features

Acorn tubes are characterized by their small, compact size and their ability to function efficiently at VHF (Very High Frequency) and UHF (Ultra High Frequency) ranges. The design includes a cylindrical glass envelope with a diameter of about 0.5 inches (13 mm) and a height of about 1.5 inches (38 mm). The electrodes are arranged in a concentric manner, which minimizes the lead inductance and capacitance, thus enhancing the tube's performance at high frequencies.

The base of the acorn tube typically has seven or eight pins arranged in a circular pattern. These pins are used to connect the tube to the external circuit. The anode (plate), cathode, and control grid are the primary internal components of the acorn tube.

Applications

Acorn tubes were widely used in radio receivers, transmitters, and radar systems during the 1940s. Their ability to operate at high frequencies made them ideal for VHF and UHF applications, including aircraft communication, navigation systems, and early television receivers.

One of the most notable uses of acorn tubes was in the proximity fuze, a type of detonator used in artillery shells and rockets. The proximity fuze significantly increased the effectiveness of anti-aircraft artillery during World War II.

Decline and Legacy

With the advent of semiconductor technology in the 1950s, the use of acorn tubes began to decline. Transistors and other solid-state devices offered greater reliability, smaller size, and lower power consumption. Despite this, acorn tubes remain an important part of the history of electronic development and are still of interest to collectors and enthusiasts of vintage electronics.

See Also

• Vacuum tube
• Thermionic valve
• Proximity fuze
• Radar
• Radio receiver
• Transistor