BERTHOLD TECHNOLOGIES LB4710-050, Руководство пользователя, Страница: 187 / 227

Chapter 3 Parameters
Mini-Switch LB 471
42
Detector high voltage
Show or set current high voltage of the detector
(only FSK detectors)
Input HV mode
-1 Automatic
500 -1300 Fixed value
The automatic HV-control keeps the detector free from drifts in
case of temperature fluctuations and ageing.
Enter a value between 500 and 1300 V to set the detector to man-
ual high voltage.
Note!
To ensure a reliable function of the measurement, the HV has to
be set to automatic.
If the count rate of a NaI detector drops below 100 counts, the HV
is frozen. If it rises again above 200 counts, the HV is again con-
trolled automatically.
HV start value
Set start value of high voltage control
(only FSK detector)
Input HV start value
0 Disabled
500 - 1300 Enabled
A HV start value fulfills the following tasks:

Default value
After turning on power, the HV starts with this value. The
measurement will be ready for operation quickly.

Limit value for the HV control range.
It limits the HV control range of the detector to max. +40%
and min. 20% of the HV start value. A HV that is too high and
therefore detrimental to the photomultiplier cannot be generat-
ed. An error message is output if the HV touches one of the
cut-off regions (see page 71).
The start value is determined in the factory and stored in the de-
tector. If the photomultiplier has to be replaced, the automatic HV
value of code 53 automatically has to be entered in code 54.
C o d e 5 3
C o d e 5 4