Waters GCT Premier Operator's Manual page 291

TDC Settings dialog box parameters:
Parameter
Trigger Threshold
(mV)
Signal Threshold
(mV)
Threshold
T0
Inhibit Push
Inhibit Value
Use DXC Tempera-
ture Compensation
Description
Sets the trigger pulse level that triggers the TDC.
Specify 350 mV, or the level set at instrument instal-
lation, if different. If peak splitting is seen, change
the value to another within the range of 200 to 700
until peak splitting is no longer seen.
TOF calibration of the instrument in EI on
See also:
page 5-2.
Sets the signal level that causes the TDC to record an
ion arrival event. The default level is 40 mV, but it
can be set at 10 to 100 mV.
See also: Setting the optimum gain for the
detector on page 10-52.
Removes any point with an intensity less than the
threshold value from the spectrum. For example, if
the setting is 5, any peak of five counts or less will not
be seen. Typically set to 0 but can be set to 1 or 2 to
remove background peaks.
This value is a correction factor for the base mass to
time equation. The default value is -50. It affects
different masses differently so adjust only if masses
are correct at high mass but are poor at low mass, or
vice versa.
Select the check box to enable the Inhibit Value field.
This is used to blank out the "pusher-pulse" seen at
approximately 6 Da.
Tip: You should use the inhibit push at all times.
Enter the inhibit value, a typical value is 4 µs.
Select the check box to enable the Drift (PPM/C)
parameter. Adjust the mass scale to compensate for
the thermal expansion of the flight tube.
Dynamic External Calibration Tempera-
See also:
ture Compensation on page 5-16.
The Tune window Settings menu B-13