5 Electrometer Module
50
Series 340 Vacuum Gauge Controller
Instruction Manual - 340005 - Rev. D
5.4 Electrometer Calibration
Refer to Section 5.3.4 for instructions on setting the ion gauge sensitivity and Section 5.3.3 for
instructions on setting the emission current.
5.4.1 Electrometer Minimum Adjustment
The Electrometer Minimum Adjustment potentiometer calibrates the electrometer for very low
inputs. This is a factory calibration point and should not be changed by the user.
5.4.2 Electrometer Scale Adjustment
The Electrometer Scale Adjustment potentiometer is a factory calibration point and should not be
changed by the user.
5.4.3 Overpressure Shutdown Adjustment
The Overpressure Shutdown Adjustment potentiometer (Figure 5-1) is factory set so the ion gauge
will shut down when the pressure rises above the levels listed in Table 5-2.
The overpressure shutoff point does not depend on the adjustment of the emission level within a
range. To adjust the overpressure shutoff point to a different level:
1.
Maintain system pressure at the desired shutoff point.
2.
Rotate the overpressure adjustment potentiometer fully counterclockwise.
3.
Turn ON the ion gauge.
4.
Rotate the adjustment potentiometer clockwise slowly until the ion gauge turns OFF.
5.4.4 A/D Calibration
This is a factory calibration point and should not be changed by the user.
Table 5-2 Overpressure Shutdown Levels
Emission Current (mA)
Overpressure Point (Torr)
0.1 range
1 x 10
-2
1.0 range
1 x 10
-3
10.0 range
1 x 10
-4
