TRANSISTOR MUSEUM Historic Transistor Photo Gallery
Transistor Size (1/2”L X 3/8”W X 1/2”H) Date Code 5-47 (1955 Week 47) on Back Plastic Tube Some Plastic Tubes Have No Markings	GE 2N78 TYPE Germanium NPN Grown Junction Hi Frequency USAGE Industrial/Mobile DATE INTRODUCED 1955 CASE STYLES Black Metal Oval Pinched Top (Early) Black Metal Top Hat (Later) AVAILABILITY Common (High Volume Production)
HISTORIC NOTES Although General Electric was known for leading in the development of alloy junction germanium transistors, this pioneering company also developed grown junction devices, building on a leadership position in germanium diode technology. The 2N78 was a very successful early germanium high frequency type, using a unique “rate-grown” process developed by GE, which used grading doping of the base region to achieve reasonable performance at frequencies up to 6 MHz. Lafayette Radio offered the 2N78 for $5.25 in 1955, and the price remained relatively high for several years ($3.75 in 1960), indicating a good market for this early high performer. As with all metal-cased GE transistors, most existing units exhibit only minor performance degradation, even after 50 years. The 2N78 continued to be manufactured through the mid 1960s.
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