LUDLUM MODEL 3 User Manual

Model 3 Technical Manual Section 3
Ludlum Measurements, Inc. Page 3-1 April 2016
Specifications
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High Voltage: adjustable from 400 to 1500 Vdc
Threshold: fixed at -35 mV ± 10 mV
Response: toggle switch for fast (4 seconds) or slow (22 seconds) from 10%
to 90% of final reading
Range: typically 0-200 mR/hr, or 0-500,000 cpm
Linearity: reading within 10% of true value with detector connected
Meter: 6.4 cm (2.5 in.) arc, 1 mA analog type
Meter Dial: 0-2 mR/hr, or 0-5 kcpm, BAT TEST (others available)
Multipliers
: ×0.1, ×1, ×10, ×100
Calibration Controls: individual potentiometers for each range; accessible
from front of instrument (protective cover provided)
End-of-Battery Life Warning: At 2.1 Vdc, the meter needle will drop to the
edge of the BAT TEST or BAT OK area when the meter selector switch is
moved to the BAT position. At 2.0 Vdc, a steady audible tone will be emitted
to warn the user of the low battery condition.
Battery Dependence: less than 3% change in readings to battery failure
indication
Reset: pushbutton to zero the meter
Audio: built-in unimorph speaker with ON-OFF switch (greater than 60 dB at
2 feet)
Connector: series ˝C˝ (other available)
Cable: one-meter (39-inch) with ˝C˝ connector (others available)
Power: two ˝D˝ cell batteries housed in a sealed externally accessible
compartment
Battery Life: typically greater than 2000 hours with alkaline batteries and
with the AUD ON-OFF switch in the OFF position
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LUDLUM MODEL 3 Specifications

General

Detector Compatibility	scintillation detectors
Power Source	Two D-cell batteries
Display	Analog meter
Audio	Built-in speaker
Operating Temperature	-20°C to 50°C (-4°F to 122°F)
Energy Range	Depends on detector
Accuracy	±10%