TRANSISTOR MUSEUM™ Historic Transistor Photo Gallery
Transistor Size (5/16”L X 3/16”W X 1/2”H) Date Code on Back 324 (1953 Week 24). 3” X 1 1/2” Cardboard Foldover Package See Page 2 for More NU T18B Photos	NATIONAL UNION TYPE T18-B TYPE Germanium Point Contact Transistor USAGE Early Switching Point Contact Applications   DATE INTRODUCED 1953 CASE STYLES Green Epoxy AVAILABILITY Very Rare (Limited Production)
HISTORIC NOTES The manufacture of both point contact and alloy junction transistors began at the National Union Radio Corp, Semiconductor Division at the Hatboro Pa. facility in 1952.  This is very early in the timeframe of transistor development, and establishes National Union as a pioneer in the history of semiconductor technology.  Transistor production was  maintained for only two years, from 1952 until 1954, when the senior management of this long established vacuum tube company decided to exit the rapidly evolving transistor market.  Both point contact and alloy junction transistor types were manufactured, with the largest sales associated with hearing aid companies, such as Sonotone, which were just beginning to introduce “transistor powered” aids in 1953.  The point contact types were likely manufactured in very low volumes, due to the limited market and the high level of production difficulties with the point contact technology.  The T18A and the T18B were the two commercial NU point contact model numbers, with each selling for $25 in the 1953/54 edition of the Radio Master catalog.  The T18A was listed as an amplifier and the T18B was listed for switching applications.  Due to the early and brief period of manufacture, and the scarcity of documentation and remaining devices, National Union semiconductor transistors are quite historic.
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