Ludlum Measurements 18, Manual

Page: 14 / 41

Model 18 Analyzer Technical Manual
Section 4
Ludlum Measurements, Inc. Page 4-1 March 2012
Identification of Controls and
Functions
Range Selector Switch
: A six-position switch marked
OFF
,
BAT
,
×1000, ×100, ×10, and ×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 (×1000, ×100, ×10, ×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.
Battery Compartment
: Sealed compartment to house two ˝
D
˝ cell
batteries.
RES Pushbutton
: When depressed, this switch provides a rapid means
of driving the meter needle to zero.
AUD ON/OFF Toggle 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, the higher the audio frequency. The audio should be
turned
OFF
when not required to reduce battery drain.
HV Pushbutton
: When depressed, displays the detector high voltage on
the meter.
F-S Toggle Switch
: Provides meter response. Selecting the fast, ˝
F
˝
position, of the toggle switch provides 90% of full-scale meter deflection
in four seconds. In the slow, ˝
S
˝ position, 90% of full-scale meter
deflection takes 22 seconds. In the
˝
F
˝
position there is fast response and
large meter deviation. The ˝
S
˝ position should be used for slow response
and damped meter deviation.
WIN IN/OUT
: A toggle switch that disables the window circuit for gross
counting.
Section
4