Transistor Museum Early Germanium Power Transistor History by Joe Knight BTL Western Electric Page 12

A SURVEY OF EARLY POWER TRANSISTORS

by Joe Knight

THE POWER TRANSISTOR

BELL TELEPHONE LABS AND WESTERN ELECTRIC

Bell Labs realized early on the necessity of building "complementary" semiconductor devices to achieve balanced circuit designs that could truly substitute for vacuum tubes applications. By 1953 development work had begun on a complement to the BTL M-1777 called the M-1897 NPN Germanium Alloy Junction Power Transistor, shown below on the left. Designed as a high-power device, capable of 2 watts of dissipated power in the standard round metal can, it had interior element construction similar to the M-1777, 2N66 and 6A types. BTL released the M-1897 data sheet as Issue 1, August, 1954.

Next, BTL developed a 'carrier' frequency medium-power transistor known as the M-2008, shown in the middle pair above. It was also a Germanium NPN Alloy Junction type with a dissipation of about .375 watts. It was first released in mid-1954. As a complement to the M-2008, BTL next developed the M-2012 (shown above as the right pair) a Germanium PNP Alloy medium-power device, designed for 'carrier' frequencies, and with a dissipation of about 1/2 watt. It also worked as a 'core memory' driver where short high-current bursts were needed at high frequencies. BTL released the M-2012 data sheet as 'Issue 1', in March of 1955.

While Bell Labs developed and made the first samples of these 'M' series types, they could not make the quantities needed for use throughout the Bell system as everyone wanted to try these new devices. The W.E. Allentown facility was assigned the task then of making these in sufficient quantities, but still with the 'M' prefix. Later on, the production power transistor manufacturing was done at the W.E. Laueldale plant. In order to protect the above exposed transistor elements from the copper case hot assembly process, they covered them in what can barely be seen in the pictures above, a brownish ozokerite wax, or 'glimp' as it was also referred to. This stuff is still sticky after all these years.

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