|1987.0487.097||Texas Instruments Collection||Object|
|Silicon Grown Junction Transistors - 1954-7
TI number: G00338
The 3N28 represents the first production high frequency silicon 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 tetrode was the only design at the time that permitted satisfactory operation at elevated temperatures.
The contract specification, MIL-T-12679A/23B(Sig C), was for a 4.3 MHz I.F. transistor. To start, state-of-the-art triodes were built. These units were acceptable except for a severe decrease in gain at elevated temperatures. Because of the results with another device (G00339), it was decided to use the tetrode design. Recognizing the need for high frequency devices, TI introduced types 924-7 in early 1956 while proceeding with the contract effort. Power gains were specified at 4.3, 12.5, 30 & 70 MHz respectively. JEDEC type numbers for these specifications in the TO-12 package outline were issued in 1957 as 2N32-5. Specification formats were rapidly evolving with increased industry applications, and this series followed the newer format rather than that of the contract. The 3N28 met its requirements but was supper ceded for production by its equivalent, the 3N32. Subsequent market and yield and experience led to production of only the 3N34 & 5, which were the only types for which registration was completed in 1958. This device is not in the correct package for the 3N28. However, because of the source, the accompanying material and the dipped painting, it likely it was built on the contract line and met specifications. Engineering work on this package was done on that line at the time. For additional information on the package, see G00339. The 3N28 indicated that it likely met specifications when completed. A lab check on 1/3/86 showed it still to have reasonable current gains (beta) and no severe degradation of breakdown voltage. These test readings and contract final report are in the Artifact Historical Files.
Related material in collection: G00008, 9, 47, 337, 9.
|Texas Instruments (Charley Earhart, Howard Moss, Harry Owens, Bob Wallace.)