Calibration
Temperature Source Calibration 4
4-11
SOUR:SENS:GRAD:DATA?
3. Repeat this 40 times to get an average of the gradient sensor reading. This value is
called “UUT grad”. Calculate the Error with this formula:
ERROR
1
= UUT grad – ACTUAL grad
4. If the magnitude of ERROR
1
is less than 0.012, skip to the next Gradient calibration
temperature and repeat the Uniformity Alignment 1
st
Iteration procedure.
5. Query the UUT GRAD 1 calibration parameter with this serial command:
SOUR:SENS:CAL:GRAD1?
6. Calculate the new Grad 1 calibration parameter as follows:
New
GRAD 1
= GRAD 1 – 0.7 x ERROR
1
7. Enter the New
GRAD 1
calibration parameter into the UUT from the front panel: MENU
> SYSTEM MENU > CALIB > CAL POINTS
or send the New
GRAD 1
calibration
parameter to the UUT with these serial commands:
SYST:PASS:CEN <password>
SOUR:SENS:CAL:GRAD1 <New_GRAD 1>
8. Let the UUT soak at the -90 °C SETPOINT for 45 minutes after the change to the
GRAD1 parameter.
9. With the UUT still at -90 °C from the previous Uniformity Alignment 3
rd
Iteration
procedure, measure the ACTUAL gradient, which is the temperature of the secondary
PRT (30 mm probe) minus the temperature of the primary PRT (0 mm probe). Take
the average of 40 samples for each of the probes. Calculate as follows:
ACTUAL grad = T
30
- T
0
10. Query the gradient sensor reading from the UUT , with this serial command:
SOUR:SENS:GRAD:DATA?
11. Repeat this 40 times to get an average of the gradient sensor reading. This value is
called “UUT grad”. Calculate the Error with this formula:
ERROR
1
= UUT grad – ACTUAL grad
12. If the magnitude of ERROR
1
is less than 0.012, skip to the next Grad cal temperature.
If the magnitude of the error is still greater than 0.012, contact an authorized Fluke
Calibration Service Center (see Chapter 1).
13. Repeat the Uniformity Alignment 1
st
Iteration procedure for the SETPOINT
temperatures listed below:
• 0 °C
• 140 °C
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