GE CTR 80 User Manual

4) The heater mode is a red light emitting diode (LED). This indicator letsthe user visually see the ratio of heating to cooling. When the indicatoris lit the heater is on, and when it is off the heater is off and the bath iscooling.5) The cooling switch turns on the refrigeration for control below 50°Cand rapid cool down.7.2 Bath Tank and LidThe bath tank and lid assembly includes: the tank, the control probe, the stir-ring motor, the access hole, and the access hole cover.• The bath tank is constructed of stainless steel. It is very resistant to oxida-tion in the presence of most chemicals and over a wide range of tempera-tures.• The control probe provides the temperature feedback signal to the con-troller allowing the controller to maintain a constant temperature. Thecontrol probe is a precision platinum resistance thermometer (PRT). It isdelicate and must be handled carefully. The probe is placed in the smallhole in the top of the bath so that the probe tip is fully immersed in thebath fluid. It is located underneath the motor cover.• The stirring motor is mounted on the bath tank lid under the motor cover.It drives the stirring propeller to provide mixing of the bath fluid. Propermixing of the fluid is important for good constant temperature stability.• On the bath lid is a work area access hole. This is used for filling the bathwith fluids and placement of thermometers and devices into the bath.When possible the access hole should be covered (must be covered toreach minimum temperatures).• An insulated access hole cover is provided and should be used to coverthe access opening in the top of the bath. This improves bath temperaturestability, prevents excess fluid evaporation or fumes and increases safetywith hot fluid. The user may drill or cut holes in the cover to accommo-date the instruments to be calibrated or immersed in the bath. Spare cov-ers are available from GE Kaye Instruments. An optional access coverwhich provides locations for two reference thermometers and three wellsfor units under test is available.7.3 Back PanelOn the back of the bath are 1) the system fuses, 2) the non-removable powercord, 3) the drain valve, 4) the RS-232 interface connector, and 5) removablevent panel.247 Parts and Controls