TRANSISTOR MUSEUM Historic Transistor Photo Gallery
Transistor Size (1/2” X 1/4”) Date Code 3-06 (1953 Week 6)(On Back of Unit) Foldover Cardboard Packaging (Banner Style Used for Black Cases Only)	RAYTHEON CK722 (Black) TYPE Germanium PNP Alloy Junction Audio Frequency Amplifier USAGE Hobbyist/Experimenter DATE INTRODUCED 1953 CASE STYLES Black Epoxy (1953 -> 1954) Blue Metal (1954 -> Late 50s) Silver Metal (Late 50s -> Mid 60s) AVAILABILITY Common (High Volume Production)
HISTORIC NOTES The Raytheon CK722 is one of the best known and well remembered transistors from the 1950s/1960s. This device was introduced in early 1953 through a series of ads in magazines designed for the electronics hobbyist, such as Radio Television News and Radio Electronics. Throughout the 1950s and into the 1960s, hundreds of these articles appeared in similar magazines. Many of the electronics and computer professionals of the past four decades first remember the CK722 as their first transistor. The first units had cases of black epoxy, while later units were made with blue or silver metal cases. These latter two case types actually consisted of a smaller hearing aid transistor encapsulated inside the metal case. The CK722 was the first mass produced germanium alloy junction transistor. Raytheon was the major manufacturer of hearing aid transistors, and those units which weren’t quite “good enough” for the demanding hearing aid market (not enough gain or too noisy) were sold to hobbyists as the CK722.
Copyright © 2002 by Jack Ward http://www.transistormuseum.com