TRANSISTOR MUSEUM

Historic Transistor Photo Gallery

 

 

Transistor Size (5/16L X 3/16W X 5/16H)

Date Code 1-57 (1957 Week 1) on Back

 

Text on Cardboard Package

 

WESTERN ELECTRIC

3N22

 

TYPE

Germanium Grown Junction

Tetrode Transistor

 

USAGE

RF Amplifier

 

DATE INTRODUCED

1956/57

 

CASE STYLES

Metal

 

AVAILABILITY

Rare (Limited Production)

HISTORIC NOTES

The earliest junction transistors performed better than the original point contact transistors in all respects except one frequency response. Whether grown junction or alloy, the first junction transistors were very limited in terms in effective operating frequency. This limitation was overcome in a number of ways, including the use of a fourth electrode attached to the base of the transistor. By proper use of bias voltages on this additional lead, the transistor could be made to effectively operate up to 15MHZ, which was fairly impressive for this timeframe. Several companies offered these four lead (tetrode) transistors, including Western Electric (3N22), Texas Instruments (3N34/35) and GE (3N36/37). By the early 1960s, other transistor technologies, such as MDT/MADT, mesa and planar were available which operated into the 100s of MHZ and the tetrodes were obsolete. Western Electric transistors were not typically sold commercially, and were available only for military and phone company uses. The 3N designation for the tetrode transistors represents the general approach of: N number + 1 = the actual number of leads, so 3N + 1 = 4; four leads on a tetrode. ( In a similar manner, note that 2N + 1 = 3; three leads on a standard triode transistor).

 

Copyright 2002 by Jack Ward

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