MKS PDR 2000 - Zero

Chapter Three: Operation
38
This adjustment is applicable to either gauge; please select the gauge by pressing GAUGE SELECT until the
desired gauge is indicated. Use
RAISE and LOWER as described above to set to the desired value.
This allows the user to select the full scale range for each CDG. Press
RAISE or LOWER to set the desired
full scale range. The full scale ranges available are 20 mTorr, 50 mTorr, 100 mTorr, 1 Torr, 2 Torr, 10
Torr, 100 Torr, 1000 Torr, 5000 Torr and 10,000 Torr.
Zero
Default Value: 0.0 (internal value)
This allows the user to adjust the zero for each CDG. Before making this adjustment, the CDG should be
connected to a vacuum system at a pressure lower than 0.1% of the full scale for the CDG. This
adjustment may also be used to set the display to a specific value if you know the pressure through other
means. For example, if the CDG to be adjusted is attached to a system that has another CDG, which has
been independently calibrated, the CDG may be made to read the same as the calibrated gauge.
The
ZERO function may be adjusted only when the CDG pressure is at 10% of full scale or lower.
Note
Pressing the [ZERO] key only adjusts the display! It does not adjust the
output of the gauge or the buffered analog output.
Note
INITIAL ZERO
When installing a CDG for the first time, it is good practice to reset the
PDR 2000 internal settings. This will prevent errors in set up; e.g., if the
CDG has not had its internal zero properly adjusted.
To reset the PDR 2000, see Reset of Stored Values, just below.
To adjust the zero, the vacuum system to which the CDG is connected
should be at a pressure lower than 0.001 times the full-scale range of the
CDG. For example, for a 10 Torr CDG, the system should be at a
pressure lower than 0.01 torr, or 10
-2
torr.
Adjust the zero adjustment on the CDG (usually a trimpot) until the PDR 2000 display shows a value
close to zero. After this initial adjustment, the display may be conveniently set to zero using front panel
controls on the Model PDR 2000.