Sample is placed in the tank coil of the oscillator. The frequency of operation is 11 MHz. A FET amplifier in the common drain configuration is used at the output stage of the oscillator to decouple the possible interdependence of power output and frequency, and to improve the stability of oscillations. For direct power absorption measurements the power output of the oscillator, after rectification across a high frequency diode, is monitored. The frequency is monitored by a counter from the signal sensed across the tank coil using a pick up coil assembly. To record the MMRA signal the output of the oscillator is fed to a phase sensitive lock-in detector.

The advantage of the present set up is the simultaneous measurement of Rs and Xs. The MMRA technique is so sensitive that even small traces of secondary phases in the sample. Which are not detectable by XRD, can be detected. The direct power absorption can be used to characterise and determine the origin of loss in these samples. Typical power absorption as a function of field and temperature in sintered and melt textured superconductors. And frequency shift as a function of temperature are shown in figs 1 &2, respectively. The loss in melt textured samples is found to be negligible when compared to sintered samples making them suitable for applications at radio frequencies.