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Transistor Size (1” OD X 3/8” Thick)   

 

Bottom View with 1/2” Bolt.  No Packaging.

 

HONEYWELL

20 WATT GERMANIUM TETRODE PROTOTYPE

 

TYPE

Germanium PNP Alloy Junction

 

USAGE

Experimental 20 watt audio power tetrode

 

DATE INTRODUCED

1957/58

 

CASE STYLES

Unpainted Silver Metal with Copper

 

AVAILABILITY

Very Rare (Prototype)

HISTORIC NOTES

Minneapolis-Honeywell was an early developer of germanium power transistors, beginning in the 1953/54 timeframe (see Joe Knight’s Survey of Early Power Transistors).  The device shown above is from the late 1950s and is a developmental prototype of a unique germanium power transistor geometry, known as a tetrode, which incorporated four leads (Collector, Emitter and two Bases).  With proper voltage biasing of the base connections, the tetrode configuration was expected to provide higher switching speed and better stability than the standard three lead transistor. By 1959, Honeywell had commercialized several high power germanium tetrodes, such as the H200EA and H200EB, with engineering samples available for the premium price of $12.50 each – other tetrode types available by 1959 from Honeywell included the 3N45/6/7/8, 3N51/2 and GAIC3.  There were two case sizes (large, as above, for higher power rating) and small, such as the 3N45. According to an engineer involved in the Honeywell tetrode program, these devices never found a successful commercial application, and were not produced in large numbers.   For an interesting tetrode application, see the 1961 Honeywell App Note by James A. Lostetter, “Two-Stage, Direct-Coupled 5-Watt Class-A Power Amplifier.”    

 

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