Environmental Restoration Group

Ludlum Model 2241
Ludlum Product Description
This instrument is a general purpose, digital ratemeter with a built-in scaler that facilitates timed counts over a user specified period. This system will store detector setup information for up to 6 detectors so trained personnel can change detectors in the field. The LCD presents readings in a 4-digit moving decimal format together with one of a wide range of available units of measure and is accompanied by several operational & alert icons. The LCD backlight can be activated and remains lit for a user-adjustable interval. This instrument features adjustable Alert & Alarm setpoints for both the Ratemeter & Scaler modes. Front panel controls include a rotary switch for selecting between Off, Ratemeter Mode and Scaler Mode, switches for audio on/off and fast/slow response time, plus push buttons for activating the LCD backlight and one for either resetting the counts or acknowledging any alarms. Calibration, user configured alarms, scaler count intervals and detector selection


INDICATED USE: General purpose survey, gross counting
SUGGESTED DETECTORS: GM, proportional, scintillation
ALERT/ALARM: Indicated by annunciation on display and audible tone
DISPLAY: 4 digit LCD display with 0.5”(1.3 cm) high digits, separate annunciators for display units, alert, alarm,low battery, detector overload, counting overflow, and scaler counting
BACKLIGHT: Pushbutton to activate
RATEMETER: Can display in R/hr, Sv/hr, cpm, or cps when selector switch is in RATE position
DISPLAY RANGE: Auto ranging from 0.0 ?R/hr - 9999 R/hr; 0.000 ?Sv/hr - 9999 Sv/hr; 0 cpm - 999k cpm; or 0 cps - 100k cps
SCALER: Adjustable from 1 – 9999 seconds (in 1 second intervals)
HIGH VOLTAGE: High Voltage: 200 – 2500 volts
DISCRIMINATOR: Adjustable from 2 – 100 mV
BATTERY LIFE: Typically 200 hours with alkaline batteries (low battery warning on LCD)
SIZE: 6.5” H x 3.5” W x 8.5” L (16.5 x 8.9 x 21.6 cm)
WEIGHT: 3.5 lbs (1.6 kg), including batteries The following parameters are adjusted for each detector by a removable switchboard. Once initial setup and calibration have been completed the switchboard can be removed without affecting normal operation of the instrument.
BACKLIGHT “ON” TIME: 5, 15, 30, 60, 90, 120, 180, or 240 seconds for backlight to stay “ON” when activated.
SET MINIMUM DISPLAY: Allows lower limit of auto-ranging display to be fixed. For example, display can be set to not show values less than 1 mR/hr.
RS-232 DATA DUMP MODE: Enables or disables binary dump mode to RS-232 port. When enabled binary data will be dumped every 2 seconds.
RS-232 DETECTOR SETUP MODE: Allows for detector parameters to be input by RS-232 port
BAUD RATE: 150, 300, 600, 1200, 2400, 4800, 9600, or 19200 bps
DEAD TIME: Adjustable from 0 – 9999 microseconds
CALIBRATION CONSTANT: Adjustable from 0.001 – 280 X 109 counts/display unit
AUDIO DIVIDE: 1, 10, 100, or 1000 events-per-click
FIXED: FAST response time adjustable from approximately 1 – 25 seconds.
SLOW response is 5 times fast setting
VARIABLE: Dependent on number of counts present. Typical times FAST – 4-25 seconds, SLOW – 4 - 60 seconds (All times stated from 10% - 90% of final reading)
RATEMETER ALERT/ALARM: Set at any value within the effective range of each detector
SCALER ALARM: Adjustable from 1 – 999999 counts
SCALER COUNT TIME: Adjustable from 1 – 99999 seconds
TEMPERATURE RANGE: -4Ί F to 122Ί F (-20Ί C to 50Ί C)
Part No. 4408-192: This option requires a firmware change on the instrument to output ASCII data.
8809 Washington St. NE • Suite 150
Albuquerque, NM 87113
Tel: (505) 298-4224
Fax: (505) 797-1404