LUDLUM MODEL 3, Technical Manual

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Model 3 Technical Manual
Section 4
Ludlum Measurements, Inc. Page 4-1 April 2016
Identification of Controls and
Functions
See the Model 3 FRONT PANEL drawing at the
beginning of this manual to reference the
following controls:
Meter
: 6.4 cm (2.5 in.) arc, 1 mA analog type with pivot-and-jewel
suspension. Typical meter dials are 0-2 mR/hr, 0-20 µSv/h, 0-5 kcpm or
combination of exposure rates (0-2 mR/hr or 0-20 µSv/h) and cpm and
BAT
TEST
.
Connector
: Used to connect the detector to the instrument. Series
˝
C
˝
is
typically used, but “BNC,” “MHV,” “UHF,” or others, can be used as well.
Range Selector Switch
: A six-position switch marked
OFF
,
BAT
, ×100,
×10, ×1, ×0.1. Turning the range selector switch from
OFF
to
BAT
provides
the operator with a battery check of the instrument. A
BAT
check scale on
the meter provides a visual means of checking the battery-charge status.
Moving the range selector switch to one of the range multiplier positions
(×100, ×10, ×1, ×0.1) provides the operator with an overall range of 0 to
500,000 cpm. Multiply the scale reading by the multiplier to determine the
actual scale reading.
Calibration Controls
: Recessed potentiometers that are used to calibrate the
individual range selections and allow for high-voltage adjustment from 400
to 1500 volts. A protective cover is provided to prevent tampering.
Battery Compartment
: Sealed compartment to house two
˝ D ˝
cell batteries.
RESET Button
: When depressed, this switch provides a rapid means to drive
the meter to 0.
AUD ON-OFF Switch
: In the
ON
position, operates the unimorph speaker,
located on the left side of the instrument. The frequency of the clicks is
relative to the rate of the incoming pulses. The higher the rate,
Section
4