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Oral History – Fred Hunter
(Continued)
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Here are various views of the 2N331 gemanium
alloy transistor which was developed by Mr. Fred Hunter in the late 1950s at
the RCA Semiconductor facility in Somerville NJ. The TA-1650A unit shown in the top photo represents the
“pre-production” or developmental type which was the precursor of the
2N331. RCA used the “TA”
(Transistor Amplifier) numbering system for developmental types. According
to documentation provided by Mr. Hunter, here are some mechanical features
for the 2N331: PNP, Germanium, Antimony Impurity for N-region, Indium
Impurity for the Collector, Indium-Silver-Gallium Impurity for the Emitter,
Case filled with DC4 Silicone grease,
Leads are sealed with glass, Lead material is Dumet (Copper Clad
Steel), and the case is gold plated on nickel-iron, copper coated. The germanium pellet is 84 x 84 x 5.5
mils, Case outline is TO-9. The 2N331 is intended primarily for
industrial audio applications.
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Oral History – Fred Hunter
(Continued)
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Here is a copy of a page from a lab report
developed by Fred Hunter as part of his early work on point contact
transistors at RCA. Note the date
(8/17/51 and the initals (FLH) on the lower right of the page. This graph shows the performance curves
of a single point contact transistor, as observed on an oscilloscope, after
the transistor has been “formed” – the forming process involved pulsing the
collector/base junction of the N-Type transistor with a capacitor charged
to a voltage between 130 to 150 vdc.
The forming process was quite labor intensive, but also essential,
since the performance of a point
contact transistor improved dramatically after forming. It is interesting to note the dramatic
progress shown between the almost “hand made “ aspects of transistor
development illustrated in this lab report, compared to the high volume, mass production, nature of transistor
development shown by the 2N331.
This was only a span of 5 years, from 1951 to 1956, but represents
tremendous progress.
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