by Joe A. Knight






My first photo is of the smaller Transistor Products Inc. (TP) power transistors.   Clevite bought out Transistor Products in 1954 and so final production items from 1955 onward will have a CT/P decal or marking.


Top Row: L-TO-R:  The first one is probably one of those early hand-made experimental versions that Prof. Fletcher made himself of the very first power device ever produced, the X-78, this from mid-1953.  The next one is still a TP prototype version of the X-78 (rated at about 2 watts dissipation) but is constructed like the finished version, finally advertised and produced in early 1954.  The next one is a TP prototype X-102 (rated at 1/4 watt dissipation), the production version which came out in early/mid 1955.  The middle item is a TP developmental device called an X-106 and has a corrugated exterior heat-sink the same height as the body (about 3/8").  The next one, although not marked, is similar in height to the X-106 but has an almost 3/4" high corrugated heat-sink - these two appear to precede the next CT/P production item, the X-107.


Bottom Row: L-TO-R:  On the left is a CT/P type X-107 production unit from early/mid 1955 – it was rated at 2 1/4 watts dissipation and has a 3/4" tall corrugated external heat-sink.  The final item is another production device, called the CT/P X-125, (rated at 1.2 watts dissipation, and no heat-sink) also released in early/mid 1955.   The CT/P “X” production types were apparently somewhat limited in numbers, as so few have survived.     


All these shown dissipation ratings came from a June 1955 Transistor Spec Chart.




Go To Transistor Products Inc Early Power Transistors, Page 2


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Joe A. Knight Early Power Transistor History – TRANSISTOR PRODUCTS INC