TRANSISTOR MUSEUM™ Historic Transistor Photo Gallery
Transistor Size (1/8” OD X 3/8”) Standard T0-24 Case 1955 U.S. Army Philco SBT	Surface Barrier Transistor TYPE Germanium PNP Surface Barrier RF/IF/OSC/SW USAGE Hobbyist/High Freq Commercial Radio and Computer DATE INTRODUCED 1953 CASE STYLES Silver or Gold Metal AVAILABILITY Common (High Volume Production)
HISTORIC NOTES Philco introduced the surface barrier transistor at year’s end in 1953. This was very early in the history of transistor technology, and the excellent high frequency performance of this new device ensured that Philco would have a leadership position as a major transistor manufacturer for the next decade. The surface barrier transistor (SBT) found almost immediate acceptance in military and commercial applications, and as prices dropped, these unique transistors found their way into a variety of hobbyist and commercial projects. The top photo shows two of the early commercial SBT types (2N128 and 2N240). The lower photo shows an early (1955, week 13) Philco L-5110 SBT prototype designated for U.S. Army usage. Because of the great success of the SBT, many other companies developed second source versions. Sprague was early to enter this market, followed by CBS, Raytheon, General Transistor and General Instrument; the SBT was manufactured throughout the 1970s. The various SBT model numbers included the 2N128, 2N240, SB100/101/102, A01, and the L series.
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