Kipp & Zonen BREWER MK IV Instruction Manual page 102

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6. A plot of the dark count and wavelength 1 intensity values vs the high voltage should be
compared to the plot in the Final Test Record.
The wavelength 1 data should exhibit a region of minimum slope (plateau).
The optimum setting for the high voltage is at the beginning of the plateau. The ratio is
determined by deviding the counts of wavelength 1 by the square root of the dark count.
If the new established optimum high voltage value deviates approximately 50 Volts or more
from the orignial setting then it is desired to change the current setting. See the HVSET
explanation on how to adjust the high voltage.
Changing the high voltage for the photomuliplier may effect the ozon
WARNING:
calibration, but will change the UV calibration for sure. The best time for
adjusting the high voltage is therefore during re-calibration of the Brewer
instrument.
HVSET: Set PMT High Voltage
HVSET is used to set the PMT High Voltage as determined from the HV test.
This test requires access to the High voltage module and the front of the Main Electronics Circuit
Board.
Prior to starting the test, locate shorting plug J2 and potentiometer R4 on the High Voltage Module,
and test point E16 on the Main Electronics Board.
Method:
1. If not already done so, then turn off Brewer power and on the high voltage module move jumper
J2 from Pins 2-3 to Pins 1-2, and restore Brewer power.
2. Enter the HVSET command and enter the desired HV value at the prompt.
3. Measure the voltage at E16 on the Main Electronics PCB and write the value down.
4. Turn off Brewer power and set jumper J2 back to pins 2-3, and restore power.
5. Monitor E16 and adjust R4 on the High Voltage Module until E16 is set to the voltage as recorded
in step 3.
6. Confirm the setting with an AP command.
4 16883
5 27775
7 40973
6 55779
10 71077
9 86191
8 99579
17 111900
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11 131484
14 138978
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15 153943
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MKIV OPERATOR'S MANUAL
APPENDIX F FACTORY TESTS
8442 869.5
12421 879.5
15486 891.5
22772 901.6
22477 911.6
28730 923.6
35206 933.6
27140 943.7
40844 955.7
39644 965.7
37143 975.7
34161 985.7
36371 995.8
39748 1007.8
37200 1017.8
36919 1027.8
37488 1037.9
35348 1049.9
38561 1059.9
34761 1069.9
34525 1082.0
34327 1092.0
32905 1102.0
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