Radio age research, manufacturing, communications, broadcasting, television (1941)

Transistors that Operate on 225 Megacycles Result from RCA Research A SIGNIFICANT advance in transistor research whicii for the first time points the way to very-high-frequency applications in television, FM radio and point-to-point radio communications has been made by the Radio Corporation of America. Several developmental point-contact transistors have been made to oscillate at frequencies well up in the lOO-to-200 megacycle band and one reached a record high frequency of 225 megaq'cles per second, according to Dr. Charles B. JoUiffe. Vice President and Technical Director of RCA. Such frequencies include the range in which FM radio and television signals are broadcast. The highest frequency value previously achieved by transistors, according to published reports, has been 50 megacycles per second. The transistor, still in the developmental stage, con- sists of a speck of germanium crystal and fine contact wires and is no greater in size than a kernel of corn. It can perform many of the functions of electron tubes. Prior to recent RCA experiments, transistors have been regarded as limited to relatively low-frequency applications. Dr. Jolliffe said. The new development promises to extend the use of the tiny transistors in high-frequency devices and to new applications in televi- sion, FM radio, point-to-point radio communication and other electronic equipment for military and civilian use. The successful development of transistors which oscillate in the very-high-frequency region was accom- plished by B. N. Slade, transistor engineer of the RCA Tube Department, RCA Victor Division, Harrison, N. J. This experimental work was conducted as a phase of RCA's transistor research program which is coordinated at the David SarnofF Research Center of RCA, Princeton, N.J. Mr. Slade pointed out that the research theory which led to the development of VHF transistors now makes possible the design of transistors which incorporate par- ticular operating characteristics for a given application. Tests conducted at the RCA Tube Department's Harrison, N. J., transistor laboratories confirmed a definite correlation between the spacing of a transistor's contact points and its frequency response. Generally speaking, Mr. Slade said, the closer the spacing, the higher the frequency. Further tests established that a transistor's frequency Point-contact transistors developed by RCA scientists. response and stability are also determined to a large degree by the resistivity of its germanium crystal. RCA transistor engineers, he explained, developed different combinations of spacing and resistivity values which enable them to design experimental transistors having a range of operational characteristics. One such combination of values also resulted in a transistor which oscillated with good stability at a frequency of 225 megacycles per second. Andean City Installs Radio Police Department Modernization of the State Police of Tiichira, Venezuela, with a Radio Police Department has been begun by Dr. Antonio Perez Vivas, governor of the Andean state. According to Meade Brunet, Vice Presi- dent of RCA and Managing Director of the RCA Inter- national Division, Dr. Perez Vivas selected RCA equip- ment after seeing the efficient performance of the system as used in Washington, D.C., where over 100 RCA mobile and fixed very-high-frequeno' units are in operation. The layout at the beginning will comprise a 250- watt transmitter and associated equipment for Tachira and several 60-watt units to be installed at strategic locations. Mobile Fleetfone units will complement the system in the city and surrounding area. 20 RADIO AGE