TRANSISTOR MUSEUM™     

Historic Transistor Photo Gallery   

 

Transistor Size (1/2”H X 5/8” OD)

No Date Codes or Packaging

 

Bottom of SX155A (Serial Number 2283)

 

RCA SX155

 

TYPE

Germanium PNP Alloy Junction

Power Transistor

 

USAGE

 Developmental/Experimental Audio

 

DATE INTRODUCED

1955

 

CASE STYLES

Black Metal Pinchtop with Integral Heat Dissipation Bolt

 

AVAILABILITY

Rare (Limited Production)

HISTORIC NOTES

The power handling capability of the first transistor types was quite limited, with the result that the audio circuits in the first commercial transistor radios produced power output of substantially less than one watt.  RCA was very active in developing transistors with improved power output and the SX155 from 1955 represents an early success.  This transistor was described by Bob Slade in the “Recent Advances in Power Junction Transistors”, which was presented at the Oct 25, 1955 meeting of the IRE Professional Group on Electron Devices.  Construction details as well as performance characteristics are captured in this paper.  Also at RCA, H.C. Lin developed several audio amplifier applications using this new transistor type, including a 20 watt Class-B audio amplifier, documented in “Transistors 1, RCA”, a 1956 compendium of early RCA transistor work.  A limited number of samples of this transistor type were produced, with hand-written labels of SX155 and SX155A-D, depending on performance characteristics, appearing on the side of the case.  Most had serial numbers written on the case top.  The “SX” designation was used at RCA to label experimental/pre-production devices.  

 

 

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