The Mode! 2166 A Multipoint Digital Thermometer is a portable four-digit, manual-scan, thermocouple thermometer capable of measuring any 1 of 10 possible like-type thermocouple inputs and resolving 1°C or 1°F over a temperature range of —200 to +2328°C or —328 to +3999°F. It features switch selection of temperature (°C7°F) and thermocouple channel (1-10), a four digit LED display, reference junction compensation (to eliminate the need for an ice bath reference junction), the choice of any one of eight thermocouple types (J, K, T, E, R, S, B or C) as the input device, dual-slope measurement techniques, digital linearization of thermocouple inputs, and power inputs for both ac line and external 12V dc operation. Several options and accessories are also available for use with the 2166A. 1-3. Front panel switch controls include a push-button power switch (ΌΝ/OFF), a push-button temperature select switch (°C/°F), and a 10-position rotary switch for selecting the desired thermocouple. The rotary switch is labeled CHANNEL Select and the thermocouple inputs are identified as 1 through 10. 1-4. The front-panel display consists of five, seven-segment, high-intensity LED’s, and features leading zero suppression. Four of the LED’s are used to display numeric data, including a minus sign for negative temperature indications. The fifth LED displays the selected °C or °F scale charac- ter. An open-thermoeouple detector causes the display to blink when an open circuit is sensed at any one of the selected thermocouple input terminals, 1-5. A plug-in module at the rear of the 2166A provides 10 pairs of screw-type input terminals for attaching individual thermocouples to the desired channels. These terminals are an integral part of an isothermal block and serve as the reference junction for the reference junction compensator. (The reference junction compensator provides the physical and electrical equivalent of, and eliminates the need for, an ice bath junction at 0°C or 32°F.) NOTE All thermocouples connected to the input terminals must be of the same type. 1-6. The actual measurement range of the 2166 A is determined by the type of thermocouples being used as the input devices. Any one of eight thermocouple types can be used; J, K, T, E, R, S, B or C. To ensure the proper linearization of the selected thermocouple input, a corresponding linearization program must be selected on the interior of the unit. Selection is accomplished by installing a type select pcb which corresponds to the input thermocouple. A single type select pcb is supplied with the unit to match the thermocouple specified at the time of purchase. The remaining pcb’s are individually available as accessories and are described in Table 1-1. I-7. Accessories and options available for use with the 2166Aare listed and described in Tables 1-1 and 1-2, respectively. Both options are field installable. Either one, but not both, of the options can be installed in a unit. Detailed information concerning each option and accessory is given in Section 6 of this manual, Option and Accessory Information.