RH Systems 2-Channel Digital Thermometer 273

The 2-channel digital thermometer is designed for stable, high precision temperature measurement over the range of -200 to +660°C. To further enhance stability, the measurement electronics are encapsulated in a constant temperature oven. Dual Range, Dual Current Source Each channel of the 273 has two distinct measuring ranges (0-100 ohms and 0-400 ohms) and associated current sources (1 mA and 300 uA respectively) allowing both 25 and 100 ohm nominal PRTs to span the full range of the Delta-Sigma A/D converter. This current source/range selection allows the system to maintain high resolution regardless of the PRT’s nominal value. Full Current Reversal Employing a full reversal current source, the 273 eliminates polarity sensitive errors normally inherent in DC measuring techniques. Accuracy is further enhanced by referencing all measurements to an internal reference resistor placed in series with the PRT to be measured. With this resistance ratio technique, the 273 accurately determines the probe resistance independent of the current source accuracy.