A Transistor Museum Interview with Ray Andrejasich

Recollections of Early Transistor Radio Technology

at Zenith Radio Corporation 

 

Oral History – Ray Andrejasich

 

 

 

 

Go To Andrejasich Oral History, Page 9

 

 

Oral History – Ray Andrejasich

Zenith #

EIA

121-426

2N3588

121-427

2N990

121-429

      2N3588

121-413

2N3588

121-414

2N3588

121-415

2N3588

121-309

2N2429

121-310

2N2428

121-425

2N2431

Zenith radios used transistors from many different manufacturers, and developed a unique numbering system to identify the many different types of transistors used in Zenith radios.  As shown below left, the Raytheon 2N111A/CK759A transistor used in the Royal 500 was also stamped by Zenith with the type identifier “121-10”.  Zenith used the “121-xxx” system for many years, through the 1960s, to identify hundreds of different transistors used in various models of Zenith radios.  Shown above is a cross-reference list recently developed by Ray to identify the more standard “2N” EIA types that correspond to the “121” numbers of the transistors in his Zenith Royal 94/990 Inter-Oceanic radio, which recently failed to function after 40+ years of frequent use.  He was able to repair the radio by replacing a failed AM/FM oscillator transistor with an Amperex 2N3588.  In addition to the “121” numbering scheme, Zenith also began using “421” in the 1960s.  Zenith sold replacement transistors to dealers for repair purposes – for example, the Raytheon 121-10 shown at left was sold as a 1950s Zenith replacement part in packaging shown at middle left.  In 1973, the Zenith Components and Accessories Division initiated the Cross Reference Sales Program (CSRP) which made a broad range of replacement transistors available.  These were identified by the “ZEN XXX” numbering scheme.  Shown above left is an example of a CRSP ZEN302 germanium replacement transistor, which can be cross-referenced to the Raytheon 2N111A transistor shown at left.     

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