A device for the measurement and quick control of the quality factor, or damping factor, of inductance coils, capacitors and resonant circuits

摘要

660,420. Q-value measurements. TESLA NATIONAL CORPORATION, and CARNIOL, B. May 18, 1949 [May 18, 1948], No. 13293/49. Class 37. Q-value or damping factor of a coil, capacitor, or resonant circuit is measured by applying a high-frequency oscillation to the resonant circuit, or to a resonant circuit in which the coil or capacitor is connected, modulating the frequency of the high-frequency oscillation at a rate sufficiently high to produce free oscillations in the resonant circuit, and detecting the beats between the applied oscillation and the free oscillations. A low-frequency oscillation, adjustable by means of a regulator R, is supplied by a tone generator A to a highfrequency generator B, which is thus frequency modulated over a wide band, for example from one half to twice the frequency determined by the circuit comprising the inductance Lx to be tested, the self capacity Co, and an additional capacity C2. The frequency modulated voltage is supplied to the coil Lx through a small capacitor Cl. The resonant circuit between the points 1, 2 acts as a discriminator and an amplitude modulated voltage is produced in the circuit and is demodulated in a detector D. The low-frequency component of the rectified voltage is supplied through a filter F to a voltmeter M. The pass band of the filter is adjusted by a regulator RSP1/SP, ganged to the regulator R, so as to pass only the frequency components produced by beating in the resonant circuit. After adjustment of the regulators R, RSP1/SP with a quality standard between the points 1, 2 the voltmeter M indicates whether the tested circuit has a Q-value above or below the standard, and may be calibrated in Q- values or damping factor.