Abstract :
This paper gives an account of work carried out by the Radio Section of the Post Office between 1925 and 1934 in the development of the use of quartz crystal oscillators in a number of different applications, of which the most important was the control of the carrier frequency of shortwave transmitters used for overseas radio services. The paper is divided into an introduction and five parts treating respectively with the crystal plate (including tourmaline and special applications involving the use of the crystal plate as resonator), the crystal holder, the oscillator circuit, the temperature control of the crystal, and results obtained in service. The importance of apparatus capable of precise frequency measurement, both in the development work and the maintenance of a high grade of service from the constant-frequency point of view, is emphasized.
