A non-contact level measurement system for monitoring distances with very high accuracy between a sensor coil and a metallic object such as a molten liquid level over either very narrow or extended distances. Controllers coupler with heaters, thermocouples, coolant air are provided for maintaining the sensor coil at a operating temperatures within the range of 400.degree. F. and 1200.degree. F. to eliminate variations to the operation of the sensor coil. The system incorporates an L-C resonant circuit connected between the output of an oscillator and the input of an operational amplifier. A variable inductor parallel with the capacitor of the L-C resonant circuit is used to obtain a precise offset operating frequency of the resonant circuit from the frequency of the oscillator.