Transistor Museum Oral History George Ludwig Explorer I Transistors Page 7

A Transistor Museum Interview

with Dr. George Ludwig

The First Transistors in Space - Personal Reflections by the Designer of the Cosmic Ray Instrumentation Package for the Explorer I Satellite

Oral History – George Ludwig

(Continued)

7) Would you provide a summary of the transistors used in the first Explorers?

The Explorer I complement was as follows:

a) Western Electric WE 53194 (4). Two each in the JPL-designed low and high power transmitters. This is a variation of the original Bell Labs 2039. The 2039 was a germanium diffused-base transistor of remarkable characteristics in the way of high frequency operation. The use of these transistors in the RF circuitry of the Explorer I satellite made it possible to have an overall efficiency of better than 25%, including power used by the oscillator, doubler buffer and modulator.

b) 2N64 (2). JPL-designed subcarrier oscillators.

c) 2N328 (8). JPL-designed subcarrier oscillators.

d) 2N496 (2). SCEL-designed high voltage power supply in the cosmic ray instrument.

e) 2N335 (17). GM counter scalers.

f) Unknown number and type in the Army’s micrometeorite amplifier.

This made a total of 29 transistors in Explorer I, plus those in the micrometeorite amplifier.

Oral History – George Ludwig

(Continued)

Explorer III had a much larger complement. The transistors were, first of all, for the germanium transistors:

a) Bendix Radio Division of Bendix Aviation 2N285A (1). Recorder control circuitry.

b) Minneapolis Regulator H27 (1). A power transistor to provide a brief high current pulse to a solenoid to advance the tape recorder.

c) Philco special high frequency L-5412 (1). JPL-designed receiver local oscillator and transmitter exciter.

d) Western Electric 45021 (2). NRL-designed high power transmitter.

Western Electric 45021 (2). JPL-designed low power transmitter. The Western Electric 45021 germanium transistors were selected Western Electric 53194 transistors like those used in Explorer I.

Then for silicon transistors:

e) Texas Instruments 2N263 (l). Switching circuit.

f) Raytheon 2N328 (1). NRL-designed high power transmitter modulator.

Raytheon 2N328 (5). JPL-designed subcarrier oscillators.

Raytheon 2N328 (1). Recording system switching circuitry.

Go To Ludwig Oral History, Page 8

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