**Introduction to Quartz Frequency Standards - Warmup**

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When power is applied to a frequency standard, it takes a finite amount of time before the equilibrium frequency stability is reached. Figure 22, discussed above, illustrates the warmup of two OCXOs. The warmup time of an oscillator is a function of the thermal properties of the resonator, the oscillator circuit and oven construction, the input power, and the oscillator's temperature prior to turn-on. Typical warmup time specifications of OCXOs (e.g., from a 0°C start) range from 3 minutes to 10 minutes. Even TCXOs, MCXOs, and simple XOs take a few seconds to "warm up," although these are not ovenized. The reasons for the finite warmup, i.e., stabilization, periods are that it takes a finite amount of time for the signal to build up in any high-Q circuit, and the few tens of milliwatts of power which are dissipated in these oscillators can change the thermal conditions within the oscillators.

Forward to "Acceleration Effects".

Back to "Thermal Hysteresis and Retrace".

Back to the tutorial's table of contents.