Historic Transistor Photo Gallery   


Transistor Size

 XN-6B  (3/8”L X 1/8”W X 5/16”H)

XN-13  (1/4”OD X 1/2”H)



Bottom View. Note Copper Heatsink for XN-6B.



XN-6B and XN-13



Germanium PNP Alloy Junction



Experimental Oil-Filled Medium Power Audio Amplifier



Mid 1950s



Unpainted Silver Metal



Rare (Limited Production)



During the 1950s, in the first few years of Motorola’s germanium transistor program, the “XN” numbering sequence was used to identify various pre-production transistor developmental types.  Shown above are two unusual types – the XN-6B (shown at left in the photos), and the (unmarked) XN-13.  Both of these types are unique in that the cases were oil-filled, which was an early experimental technique used to increase the heat dissipation capability of the devices.  Increased heat dissipation enhanced the amount of power that the devices could accommodate, and higher power transistors were in great demand during this timeframe, especially as audio amplifiers.  The XN-6B has a stamped date code (1956, week 26) and apparently was supplied with a small copper heat sink.  The rectangular metal case style is similar to other Motorola XN types, such as the XN-1 and XN-2.  The cylindrical case style for the XN-13 is quite unique, and likely represents an experimental effort to investigate different case styles.  Tentative data sheets from Jan 1957 indicate that there were three separate versions for this device – the XN13A, XN13B and XN13C, which correspond to the final 1958 production types MN13A, MN13B and MN13C.  These were listed as medium power types for audio frequency circuits.   


Copyright © 2006 by Jack Ward.  All Rights Reserved.