Transistor Museum Early Germanium Power Transistor History by Joe Knight BTL Western Electric Page 5

A SURVEY OF EARLY POWER TRANSISTORS

by Joe Knight

THE POWER TRANSISTOR

BELL TELEPHONE LABS AND WESTERN ELECTRIC

In the first special "Transistor Issue" of the IRE Proceedings (November of 1952) there were already references to the development of unique Power Transistor designs, such being the widespread interest in semiconductor power devices. Some of these were claimed capable of output levels in the range of 2-3 watts of dissipation.

Bell Labs had by 1951 already experimented with power point-contact devices with external heat-sinks. Later in 1951, Mr. Pete Pietenpol (see his Transistor Museum oral history interview) had begun work using the somewhat limited 'grown junction' process for transistors. By 1952 his BTL transistor group was investigating this technology for use in possible Power Transistor designs. And later in 1952, Mr. Mason Clark was assigned to take over the BTL Power Transistor development program. Fortunately, at about this same time, Mr. Robert Hall & Mr. John Saby at GE and Mr. Charles Mueller at RCA (see their Transistor Museum oral history interviews) had developed the germanium 'alloy junction' process. Through mutual semiconductor cross-licensing agreements among all the major electronic firms, Bell Labs was soon able to manufacture their own alloy junction ingots and make real progress in the technology development of Power Transistors. By the end of 1952 Bell Labs had designated a prototype model called the medium power M1777, a Germanium PNP Alloy Junction Power Transistor. This device was rated at about 1+ watt of dissipated power and would develop over the next year into the first of a long line of notable BTL Power Transistors. The M1777 was first field tested in a rural Georgia telephone system about 1953-54 to prove its reliability. It must have done just fine as this basic design lived on in other BTL versions for several more years.

The photo above shows an early M1777 (c. 1953) in its usual black round welded can.

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