Model 6485 Instruction Manual Calibration 16-7
5. Enter the current calibration code on the display. (Factory default: 006485.) Use
the up and down RANGE keys to select the letter or number, and use the left and
right arrow keys to choose the position. Press ENTER to complete the process, and
the unit will display:
CAL UNLOCKED
Followed by:
NEW CODE? N
6. With N displayed, press ENTER.
Offset voltage calibration
Before performing the remaining calibration steps, perform input bias current and offset
voltage calibration as outlined below.
1. From the calibration menu, use the up or down RANGE key to display the follow-
ing:
CAL: VOFFSET
2. Press ENTER. The instrument will prompt as follows:
INPUT CAP
3. Connect the BNC shielding cap to the rear panel INPUT jack.
4. Press ENTER to complete offset voltage calibration.
5. Press EXIT to return to normal display.
Current calibration
20µA-20mA range calibration
1. Connect the BNC shielding cap to the Model 6485 rear panel INPUT jack.
2. Select the Model 6485 20µA range.
3. Press MENU, select CAL, then press ENTER. At the CAL: RUN prompt, press
ENTER. The unit will prompt for the zero calibration point:
20µA ZERO
4. With the BNC shielding cap connected to the INPUT jack for a 0µA input current,
press ENTER.
5. The unit will prompt for the positive full-scale cal point:
+20µA CAL
6. Connect the current calibrator to the Model 6485 INPUT jack, as shown in
Figure 16-1.
7. Press ENTER. The unit will prompt for the positive full-scale current:
+20.00000 µA
8. Set the calibrator current to +20.00000µA then adjust the display to agree with the
calibrator current.