TRANSISTOR MUSEUM™  Historic Transistor Photo Gallery
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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