The output voltage of the system was measured while the PT was heated. Since the parameters of the PT are temperature dependent, the frequency of maximum output voltage is expected to change as the temperature of the PT is varied. Fig. 11 summarized the measured output voltage when the PT was exposed to a temperature change of 30 C to 65 C.With frequency tracking the voltage drop at 65 C was only 2% while with no tracking the output voltage dropped by 34%. It should be pointed out that the small 2% variation could be due to less efficient operation at the elevated temperature and not necessarily improper frequency tracking.