Initializing The Display
To adjust a parameter setting, first make sure that the corresponding LED is lit. Then
press the DIGIT SELECT button until the digit that is to be changed blinks. Once the
digit is blinking, use the INCrement/DECrement Switch to change the setting.
To advance to the next digit, press the DIGIT SELECT switch again. Repeat this for
as many digits as necessary, then press the DIGIT SELECT button one or more times
until all digits are steadily lit. Note that either of two digits can be changed when
adjusting BIAS voltage and DISCriminator and CALibration pulser energies. Any of
five digits can be changed in Preset Time (P-TIME).
The Model 7401’s internal memory maintains BIAS, DISCriminator and
CALibration pulser settings when the unit’s power is turned off. To insure proper
memory operation, make sure that all changes to these settings have been completed
before turning the 7401’s power off.
If the BIAS Function is selected, the display always indicates the voltage applied to
the detector bias network. If the BIAS Switch is turned off, the bias will remain close
to zero volts. Once the BIAS Switch is turned on, the display will show the detector
voltage as it increases to the bias level stored in internal memory.
Initializing The Display
The front panel display is initialized to show the Bias whenever the unit’s power is
turned off, then on. To aid in testing, it can also be reset and initialized by
simultaneously pressing the RESET and DIGIT SELECT push buttons while
pressing the INC/DEC Switch to the INC position. When the unit is reset, the stored
BIAS, DISCriminator, and CALibrate settings will not be changed.
Applying Vacuum
Applying the vacuum is done in three steps:
1.
Set the display to read VACuum.
2.
Start the vacuum pump.
3.
Pull the valve handle out to the PUMP position and rotate the handle -turn
counterclockwise (Figure 6). The gurgling sound should stop in a minute or
so if there are no leaks in the vacuum line.
Figure 6 Valve Operation
7401/7401VR Alpha Spectrometer User’s Manual - 9231603C
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