1987.0487.098 Texas Instruments Collection Object

Silicon Grown Junction Transistors - 1954-7
TI number: G00339

These 3N24 transistors represent production of the first silicon high frequency transistors. The work was performed in 1954-7 as part of the effort on U.S. Army Signal Corps Contract No: DA-36-039-SC-54703. The package and the tetrode configuration are of interest.

The contract specification, MIL-T-12679A/24B(Sig C), was for a 12.5 MHz I.F. transistor. After evaluating state-of-the-art triodes, it was decided to use the tetrode design. The 3N24 satisfactorily met the contract requirements; however, it was super ceded by the 3N33 for production. (See G00338 for details.) These units were surplus from the contract pilot manufacturing line. The symbolization indicates they met specifications at the time. The "980715" is the TI Federal Stock Number, 980, and the Manufacturing Date Code, 715, which is for the 15th week of 1957. The three devices were given a limited lab check on 1/3/86. Current gain (beta) was reasonable, and there appeared to be no serious degradation of breakdown voltage. These test results and a copy of the contract Final Report are in the Artifact Historical Files. The package size designation was listed as JETEC Group 30. The lead pitch circle diameter of .200" fitted the industry preference for the .100" printed board grid. Also, it was more convenient for use with the tetrode structure. Although it was used for this project, TI recognized several shortcomings. The limited glass thickness between the leads and the rim offered potential leaks from the stress of welding and lead handling. The position of the weld flange provided chance for flash to enter package and/or the eyelet rim to separate from the glass, breaking the hermetic seal. Consequently, TI initiated a modification which slightly increased the outside diameter and allowed the flange to be at the bottom. This became the industry standard JEDEC TO-5 for triodes and TO-12 for tetrodes.

Related material in collection: G00008, 9, 47, 337, 8.
Texas Instruments (Charley Earhart, Howard Moss, Harry Owens, Bob Wallace.)

Contact Nance L. Briscoe for further information

National Museum of American History

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