The measurement of frequencies in the range 100 Mc/s to 10,000 Mc/s

The description is given of a simple portable apparatus with which frequencies in the range 100 Mc/s to 10000 Mc/s can be measured in terms of that of a standard quartz oscillator. Two oscillating detector stages are used. A heterodyne beat is obtained between the signal of frequency f and the nth harmonic of oscillator 1. A second beat is obtained between oscillator 1 and the mth harmonic of oscillator 2. Oscillator 2 is thus set at a frequency of f/mn. The frequency scale of oscillator 2 is then calibrated by the harmonics of oscillators controlled in frequency by a quartz oscillator, and the frequency corresponding to the setting f/mn is found by interpolation between the calibration points. The accuracy of the measurement in terms of the frequency of the quartz oscillator is ± 1 part in 106; but for an overall accuracy of this order it is usually necessary to check the frequency of the quartz oscillator. The size of the instrument, excluding power supply equipment, is 27 in × 9 in × 12 in, and its weight is approximately 30 lb. The apparatus is designed to operate from batteries or a stabilized mains supply providing 300 volts h.t. and 6 volts for the heaters.