Ludlum Measurements 177, Руководство пользователя

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Model 177
Technical Manual
Section 4
Ludlum Measurements, Inc. Page 4-3 October 2018
PIN 3:
instrument common (ground).
PIN 4:
alarm sink. The open collector of a 2N7002L. Limits
sink current to 200 milliamperes with open circuit voltage
limited to a range of 0 to +50 volts. Unit conducts when in
alarm.
PIN 5:
Pulse out. A negative pulse connected to the
discriminator output through a 0.001
µ
F capacitor,
typically -4.0 volts.
PIN 6:
Unbuffered output ties directly to the meter drive
circuit. (R124/C122). Approximately 1.3 volts at full scale.
Using an external constant current sink will allow background
subtract. At full scale, draws out approximately 3.3
microamperes to zero the meter.
PIN 7:
Recorder output, adjustable from 0 to 1.0 volts at
1 milliamperes.
PIN 8 and PIN 9:
Spares
CAL Control
Remove the calibration (cal) cover plate to access the following calibration
potentiometers:
DISCR:
Discrimination Control. For pancake-type GM detectors (i.e.
Model 44-9), adjust
DISCR
for 80
±
10 millivolts. All other GM detectors
and scintillators should be set to 35
±
10 millivolts. If a lower operating
voltage for a scintillator is desired, adjust the discriminator to 10
±
2
millivolts. This control has an adjustable range of 10 to 100 millivolts. A
Ludlum Model 500 Pulser may be used to determine the discrimination
level.
Calibration Controls:
X1K through X1 calibration controls used to
calibrate ranges.
HV ADJ:
used to set detector operating voltage.
RCDR:
used to calibrate the recorder output.