Quartz-Crystal Measurement at 10 to 180 Megacycles

A method is described for measuring the equivalent parameters of both the main and spurious modes of very high-frequency crystal units. The crystal is placed between the plate and cathode of an amplifier tube, and the voltage developed across it is recorded as a function of frequency. The series resistance R88. can be obtained by comparing the resulting voltage peaks with the voltage developed across a pure capacitive load. The series capacitance C8 is measured by recording the resonance curve with the crystal unit in circuit, and then recording a second resonance curve when the capacitance across the crystal unit has been increased by a known amount. The frequency difference between the two curves gives a measure for C8. Correction functions are derived for evaluating the recorded data for crystal units having high R8 and low reactance of the static capacitance Co.