Historic Transistor Photo
The Raytheon CK718 was the first transistor made available for large scale hearing aid usage. Throughout the 1940s and early 50s, Raytheon was the leading manufacturer/supplier of subminiature vacuum tubes to hearing aid manufacturers. In order to protect this market, Raytheon moved quickly to transistor technology – this was in anticipation that the features provided by the transistor (low power consumption, small size, ruggedness) would revolutionize hearing aid design. As early as 1950, Raytheon experimented with point contact transistors, but found these to be too noisy and not robust enough for hearing aids. Shortly after junction transistor technology became available in 1951/52, Raytheon established large scale production of alloy junction transistors, building on the research of this technology done at GE and RCA. By late 1952, Raytheon was making thousands of the CK718s every week and began to supply these immediately to the major hearing aid manufacturers. The CK718 was sold only to hearing aid companies. The earliest units had the three digit date code on the back, while later units had the three digit date code on the front. The CK718 was produced into 1955, when newer hearing aid transistor technology was introduced by Raytheon.
© 2002 by Jack Ward