Abstract
Attention is drawn to the use of phase locking of two oscillators for the measurement of transient magnetic or dielectric changes of samples placed in a resonator. Improvements in speed and sensitivity are possible over other methods. A specific design for operation at 10 MHz is given for the measurement of magnetic susceptibility changes at low temperatures. As an example of the results obtained, the magnetic canting transition of KMnF3 near 82 K is shown.