Abstract: A radiation resistant meter for use in intense ionising radiation fields ludes a meter unit (10) coupled to a separate processing and indicating unit (50) by means of a radio link (24,35). Radiation sensitive components in the voltage amplifier (14) and low frequency oscillator (16) are replaced by valves. Certain radiation sensitive components are covered in a potting compound. A calibration system formed from five zener voltage references (28) is located close to the sensor (12) and coupled to the same circuitry by a multiplexer (30), as is a thermistor (24) the signals from the components (12,26,28) are fed to the amplifier (14) in cyclical manner and processed by a computer (40) in the receiving unit (50). From the calibration voltages (28), the computer determines a calibration curve used for determining the magnitude of the parameter sensed by the sensor (12). The meter can operate at and measure radiation levels far higher than previously known equipment.