Front-Panel Operation
Sample Applications 4
4-67
Note
Specified voltages are necessary for the subsequent steps to be at the inputs
of the Thermometer. With the 10
μ
V/
°
C type thermocouple selection of the
Calibrator, you can choose the output voltage on the TC terminals.
5. Push , , and . Make sure the softkey named OUTPUT shows “tc”.
If not, push the OUTPUT softkey until it does.
6. Push the TYPE softkey until 10μV/°C is shown. This selection lets you choose the
voltage on the TC terminal.
7. Push the TC MENU softkey.
8. Push REF SRC softkey until “external” is shown.
9. Push the REF softkey to record an external reference value.
10. Push and to set the external reference to 0 °C.
11. Push to move to the last menu level.
12. Push .
13. Let the UUT indication become stable and then adjust the T1 offset adjustment (R7)
for in indication of 25.2 °C ±0.1 °C.
14. Change the Calibrator output to 5380.7 °C. This puts 53.807 mV on the tc terminals.
15. Let the UUT indication become stable and adjust R21 for a display indication of
+1370.0 °C ±0.4 °C.
16. Push on the Calibrator to remove voltage from the UUT. Disconnect the UUT
from the Calibrator. Short the ON/OFF switch grid to turn off the UUT.
17. With an elastomeric switch pad in your left and right hands, use the left one to short
out the TP2 grid, and use the right one to first turn on the instrument and then quickly
short out the VIEW switch grid. Hold this position until the display is held in self-
test. This puts the UUT into the Reference Junction Sensor calibration mode, and the
VIEW procedure turns off a filter so that the indication was stable immediately.
18. With a type K thermocouple bead (supplied with the 5520A-525/LEADS test lead
kit) and the Calibrator MEAS TC mode (push ), measure the reference junction
transistor temperature. To do this, put the K-bead into the middle hole of the
isothermal block. The bead tip must be put into the well, against the body of Q1. To
do this, cover the well and set the bead with a piece of tissue to help the bead stay in
position. Do not hold the bead in position with your hands as this can introduce a
measurement error. Let the temperature indication become stable.
19. Adjust R16 for a temperature indication on the UUT that is the same as shown on the
Calibrator.
20. Power down the UUT and assemble it.
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