Abstract :
The paper describes a stable tunable oscillator for wavelengths of about 3.2 cm, which was designed in 1941 primarily for use in radar sets as a beating oscillator in superheterodyne receivers. The oscillator has been manufactured in three types, known as the CV87, CV129 and CV223, which differ only in the type of tuning mechanism used, and in the tuning range covered. A harmonic resonator is used in conjunction with the disc-seal construction, the glass being situated at a voltage node in the resonator so as to minimize dielectric loss. Tuning is effected by flexing one of the resonator diaphragms, thus varying the capacitance between two rims situated at the outer antinode of the resonator. The average output power, at the nominal input of 1600 volts 10 watts, is over 100 mW. Dimensional details and characteristics are given, as well as a short account of the experimental development of the oscillator. The factors affecting the performance are mentioned and discussed on the basis of the first-order theory of N.C. Barford and M.B. Manifold, by means of which the efficiency is calculated and compared with the experimental value.
