TRANSISTOR MUSEUM™ Historic Transistor Photo Gallery
Diode Size (1/8” Diameter X 3/8” L) Date Code on Yellow Unit 013 (1950 Week 13) No Date Code on Red Unit 3” X 11/2” Cardboard Package Labeling See Page 2 for More CK705 Diode Photos	RAYTHEON CK705 GERMANIUM  CRYSTAL DIODE   TYPE Germanium Point Contact Diode USAGE General Purpose/1N34 Equivalent DATE INTRODUCED 1949/1950 CASE STYLES Yellow Epoxy (Early) Red Epoxy (Later) AVAILABILITY Rare (Production Limited to 1950s)
HISTORIC NOTES In 1948 Raytheon began the manufacture of germanium diodes for use in UHF tuners in television sets.  Large scale production followed in 1949 and increased to such an extent that by the end of 1950, close to 100,000 were being built every month. By 1952, Raytheon was the 2^nd largest manufacturer of germanium diodes, and continued to be a leading germanium diode manufacturer throughout the 1950’s, with sales of $1.5 million in 1956 alone.  These first Raytheon germanium diodes, also known as Crystal Rectifiers, had rough epoxy cases that were not hermetically sealed, and the internal diode junctions would often show degraded performance through time due to moisture penetration.  By the mid 1950s, more robust, sealed cases were used.  The most popular 1950s Raytheon Crystal Diode was the CK705, shown above in a 1950 yellow epoxy case.  This device was intended for general purpose applications and competed directly against the famous Sylvania 1N34 diode.  The Raytheon CK705, yellow or red, is well remembered by many electronics hobbyists from the 1950s, when this strikingly colored device was used in that first homebuilt AM radio!
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