Characteristics of Vacuum Tubes for Radar Intermediate Frequency Amplifiers
01 July 1946
"Stevens Point and Minneapolis Linked by Coaxial System," K. C. Black, Bell Laboratories Record, January 1942, pp. 127-132. "Television Transmission Over Wire Lines," M. E. Strieby and J. F. Wentz, Bell System Technical Journal, January 1941, Vol. 20, p. 62. 385 1 characteristics determine the frequency bandwidth, amplification, and signal-to-noise ratio attainable with such an amplifier. The maximum operating frequency is generally limited by the input resistance of the tube which decreases as the frequency is increased, and, in some cases, by the tube ยท noise which increases with increasing frequency. Three other characteristics which are also important are small physical size, low power consumption, and ruggedness. The present paper describes how these characteristics are related to the performance requirements for intermediate frequency (IF) amplifiers used in radar systems and shows how the requirements were met in the design of the Western Electric 6AK5 Vacuum Tube. In a coaxial cable carrier telephone system of the type which was initially installed between Stevens Point, Wisconsin and Minneapolis, Minnesota the upper frequency of the useful band is of the order of three megacycles per second (mc) and the bandwidth is of the same order. The Western Electric 386A tube was developed a number of years ago for amplifiers such as those used in this system. It is characterized by high transconductance and low capacitances. In radar receiving systems similar but more exacting requirements must be met for the IF amplifier.