The vacuum tube plays a dual role in the history of technology. In addition to its behind-the-scene significance as one of the principal enabling technologies for long-distance telephony, radio, radar, television, and (at first) the electronic computer, it was familiar to the general public as well. Untrained but eager home handymen ventured to replace tubes when the family radio went on the fritz, resulting in a substantial direct-to-consumer market for vacuum tubes which grew along with the market for radios. Following World War II, television further increased the market for consumer vacuum-tube sales. The do-it-yourself tube testing machine was a fixture in many supermarkets and convenience stores through the 1960s until solid-state electronics essentially extinguished demand for most tubes.
The public’s direct awareness of the significance of the vacuum tube during much of the twentieth century gives the Manhattan College Tube Museum a broader appeal than many other specialist museums devoted to a particular category of technological artifacts. Starting with a few dozen tubes displayed at the Paramus (New Jersey) Catholic Boy’s High School in 1976, science teacher Brother Patrick Dowd, F. S. C., obtained permission from Manhattan College in 1978 to use the walls of the college’s new engineering library reading room to mount display panels of tubes of historical and technical interest. Over the years, Bro. Dowd has diligently traded and augmented his inventory so that it now features a historically representative variety of vacuum tubes used in radio transmitting and receiving, television imaging and reception, radar, and many other scientific, industrial, and medical applications. The entire collection of over 4,000 vacuum tubes is now on permanent display in 78 wall panels and several shelves above them which support the larger and heavier devices. Most of the panels have a few sentences of explanation, and some of these are written so that the nontechnical visitor can understand what is going on. Unfortunately, photographs to help contextualize the artifacts are rare.
The collection represents mostly American types, but some historically significant foreign tubes are included as well. The chronological range of the collection extends from an experimental tube made by Lee DeForest shortly before he patented his “audion” in 1907 to the last miniature “nuvistor” tube made at RCA’s Harrison, New Jersey, plant before it closed in 1976, as well as more recent examples. Also featured are many experimental and pre-production tubes and tube components which give insight into the engineering research and production methods involved in this technology. Rather than attempt a complete survey, I will describe two of the more unusual items to give some idea of the range and depth of the collection in this unique museum.
<- Figure 1. The 4-foot (!) Westinghouse AW-200 had pipe connections for cooling water to enable it to produce 50,000 watts of power for 1930s radio and television transmissions.
In 1936, Westinghouse introduced the AW-200 transmitting tube (figure 1). Over four feet long and capable of producing 50,000 watts of radio-frequency power, this water-cooled behemoth served in RCA’s experimental television station W2XBS atop the Empire State Building in the 1930s. The same research group responsible for this line of high-power devices at Westinghouse also performed early work on the microwave magnetron, which Randall and Boot of the University of Manchester developed into a source of high-power pulses for radar during World War II.
<- Figure 2. This Japanese magnetron tube was used in radio or radar receiving equipment on board a World War II naval ship. Although less advanced than the British microwave cavity magnetron tube, it embodied the same basic operating principles.
It is less well known that Japanese researchers were doing high-frequency magnetron work as early as 1927, and developed magnetrons for wartime use such as the “four-leaf-clover” unit shown in figure 2. Although Japan and Germany did not pursue radar development to the same extent that the Allies did, artifacts such as this one show that the magnetron was by no means confined to the Allied side of the conflict.
The Manhattan College Tube Museum is open whenever the college is in session. It is located in the Engineering Building on Corlear Avenue between 238th and 240th Sts. in the Bronx, a short walk from the 242nd St. terminal of the IRT line (Van Cortland Park). Visitors desiring to view the collection should call for the library’s hours (718) 862-7295. Brother Patrick Dowd, who curates the museum and writes a column about tubes for the Antique Wireless Association quarterly journal, can be reached at 4415 Post Road, Bronx, NY 10471-3499, (718) 796-9482. Anyone who wants to know whether a particular U. S. vacuum tube is extant and available for historical study should check with Bro. Dowd, who keeps a complete and detailed inventory of all tubes on display.
Karl D. Stephan teaches electrical engineering at the University of Massachusetts Amherst. He has received an NSF Science and Technology Studies Fellowship and plans to work with Bruce Hunt at the University of Texas at Austin on the history of communications technology during the 1999-2000 academic year.