AEMC CA846 [2121.24] Thermo-Hygrometer, -4 to 140°F (-20 to 60°C). The Thermo-Hygrometer Model CA846 is a portable, compact digital meter designed for simplicity and one-hand operation. The meter uses an RTD Pt385/1000Ω as the temperature sensor, providing excellent response time to changes in temperature, good repeatability and accurate readings. The Model CA846 also utilizes a thin polymer capacitive type relative humidity sensor as hygrometer sensor, offering excellent recovery from 100% moisture, and fast response time and durability.