Substantiation of aging characteristics of PCM timing detect and turning circuit for 20 years

The authors began to develop a tuning circuit in 1963. It consisted of an inductor, a fixed capacitor, and a variable capacitor connected in parallel. The inductor is a Ni-Zn ferrite pot-core coil; the fixed capacitor is a metal-cased MgTiO₃ ceramic capacitor; and the variable capacitor is a glass capacitor. The specimen was left at ordinary temperature for 20 years from 1966 in order to measure its aging characteristics. The 20-year changes in the resonant frequency of the circuit, the inductance and the capacitance under ordinary temperature have proved to be approximately linear with respect to the logarithm of time without any exceptions. The design and results coincided well in the changes of their mean values and dispersions. This means that the initial design concept was correct. Since the constants inherent to the inductor and capacitor change linearly with the logarithm of time, their values after long-term aging can be predicted from short-term measurement data. The acceleration coefficient for predicting the characteristics after 20-year aging is as follows: 10⁶ (20 years/10 min.) for the inductor and 700 (20 years/10 days) for the capacitor