A Transistor Museum Interview with Ray Andrejasich

Recollections of Early Transistor Radio Technology

at Zenith Radio Corporation



Photo Courtesy of Bob McGarrah. Used with permission. See Bob’s excellent Zenith R500 website for more information.



Zenith began production of its first transistor radios in 1955, with the famous and well remembered Royal 500 series.  Shown above are photos of the front views of two 1955 era R500s, as well as a photo of the top view of the circuit board.  These first R500s contained seven transistors, all mounted in plug-in sockets, to allow for fast repair of failing transistors.  Many of these transistors were individually tested at Zenith to determine performance and then color coded to facilitate circuit placement; you can see the blue and orange paint swatches on the transistors in the chassis above.  Zenith used transistors from four different manufacturers for the early Royal 500 series of radios: RCA (black case at bottom of left photo), Texas Instruments (silver), Raytheon (silver case 3rd from bottom), and Sylvania (black unit at top of left photo).  Zenith stamped these transistors with its own unique identification sequence, of the form 121-XXX, with the last three digits identifying the actual type of transistor.  Note the RCA is marked 121-66, TI unit is marked 121-18, and Raytheon is 121-12.  The Sylvania is marked 121-7 on the opposite side of the case.  Most all of these early transistors used in R500 radios carried both the original manufacturer’s stamp and the Zenith 121 Number.  Ray started at Zenith in May of 1957, so the R500 was in full production at that time and he had the opportunity to work directly with these early and truly historic transistors. 


Go To Andrejasich Oral History, Page 4

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