Calibration Procedure; Equipment Required; Calibration - Wahl Heat-Prober 392AHP User Manual

Heat-Prober
13.2 Calibration Procedure (See Figure 13-1)

13.2.1 Equipment Required

1. Digital Voltmeter, Fluke 8600 41/2 digit or equivalent.
2. Decade resistance box with a range to 30K and resolution to one ohm. Accuracy
required can be determined by using the thermistor slope at 60°C where an error of 1 ohm is
equivalent to .01°C.

13.2.2 Calibration

1. Connect DVM(+) to TP2 and (-) to TP1. Turn on power switch and adjust R15 for a
DVM reading of 2.110 ±.002 volts. This sets the low battery indication point at a battery voltage
of 5.5 Volts.
2. Connect the decade resistance box to the unit to be calibrated by using a cable length
of approximately five feet of 22AWG wire and a Switchcraft #250 plug connector.
3. Set resistance to 29,490 ohms and adjust R5 for a display reading of 0.00°C (32°F).
4. Set the decade box to a resistance of 2760 ohms and adjust R13 for a display reading
of 60.00°C (140.00°F).
5. Set the decade box to a resistance of 12260 ohms and check the unit for a correct
display reading of 20.02°C or 68.03°F.
6. Repeat steps 3, 4 and 5 as necessary for best calibration.
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Platinum-RTD Thermometers User Manual
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