Model 979 Series Helium Mass Spectrometer Leak Detector
3-4
DRAFT 9/15/03
3.1.1.2 Gain
Touch the GAIN box to manually adjust the calibration gain. The gain parameter is used to
calibrate the leak detector to a known helium source. The gain parameter is adjusted after
the leak detector has been tuned to helium.
Typical gain values range from 0.5 to 5.0. The gain value is automatically set during the
Calibration routine. The higher the gain, the more noise shows up in the least sensitive
range.
3.1.1.3 Offset
The variable displayed in the OFFSET box represents the current value of the preamplifier
offset. This value is used by the service technician to evaluate the condition of the preampli-
fier. The normal operating range is between 35 and 80. If this value is outside of the range,
contact your local Vacuum Technologies service representative.
3.1.2 Manual Spectube Tuning
Touch the MANUAL SPECTUBE TUNING box to display the Manual Spectube Tuning
screen (Figure 3-5). This screen is used to manually adjust the parameters of the Ion Source
in the spectrometer tube for a maximum helium signal.
Figure 3-5
Manual Spectube Tuning Screen
MANUAL SPECTUBE TUNING
REPELLER V: XXX.X
ION V: XXX.X
ESC
DONE
VAR FOCUS: XXX.X
OK
FIL
1
ACTV
EMISSION I: X.XXX
SUPRESSOR: XXX.X
FIXED FOCUS: XXX.X
BACK
MANUAL
ZEROING &
CALIBRATE
MANUAL
SPEC TUBE
TUNING
MANUAL
VALVE
CONTROL
SYSTEM
INIT
SET-UP
GAUGE
CAL
DN
UP
Summary of Contents for 979 Series
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