Model 375 Area Monitor

Ludlum Measurements

Model 375 Area Monitor Model 375 Area Monitor, left side Model 375 Area Monitor, bottom

The Model 375 is a versatile, compact, and very affordable digital electronic controller designed for monitoring radiation in areas. Its simple design accommodates many different detectors suiting a wide variety of applications, and is equipped with a local readout and alarms. These versatile units may also be connected to an optional auxiliary indicator/annunciators for alerting personnel at remote locations. The user-friendly, digital design enhances setup and operation. These units may also be networked to a central PC-based station where data are logged and alarms posted.

This affordable and very flexible system has found its way into many applications resulting in a full complement of detectors, accessories, and options that include remote indicator alarms, printers, relay outputs, weather-proof enclosures, Ethernet networking software, industrial cameras, and more. See Options List.

Sites requiring centralization of their data can link multiple 375 systems together via ethernet and view them using a common web browser with the purchase of Ludlum's Webpage & Service Software. This program collects all data in real time, logs data, and annuciates any alarms. The system can also send intelligent e-mail alerts to responsible personnel and capture a picture of whatever triggered an alarm anywhere optional Ethernet cameras are employed.

Indicated Use Area monitoring
Suggested Detectors GM, proportional, scintillation, neutron
Display Four-digit LED display with 2 cm (0.8 in.) digits
Display Range 0-9999
Display Units μR/hr, mR/hr, R/hr, μSv/h, mSv/h, Sv/h, μrem/hr, mrem/hr, rem/hr, cpm, cps, and others
Audio Intensity can very from approximately 68 dB to 100 dB through operation of the external rotary baffle and the internal voltage connection. Frequency is approximately 3 kHz
Linearity reading within 10% of true value
Response typically three seconds from 10%-90% of final reading
Status green light, instrument functioning properly
Low Alarm yellow light, 1 beep/second audible, selectable range: 0-9999
High Alarm red light, 4 beeps/second audible, selectable range: 0-9999
Detector Fail red light, constant audible tome > 68 dB at 61 cm (2 ft)
Low Bat yellow light, indicates less than two hours of battery life remaining
High Voltage adjustable from 200-2500 volts
Threshhold adjustable from 2-100 mV
Dead Time adjustable to compensate for dead time of detector and electronics (can be read on display)
Overload senses detector saturation (indicated by display reading “-OL-”)
Overrange indicates radiation field being measured has exceeded counting range of instrument (indicated by display reading “– – – –”)
Data Output nine-pin connector providing five-decade logarithmic output, RS-232 output, signal ground connection, FAIL, and ALARM signals (current sink), and direct connection to battery and ground
Calibration Controls accessible from front of instrument (protective cover provided)
Power 9 Vdc wall-mount adapter, handles any mains voltage in the world, supplied with four sets of prongs for almost any style wall receptacle
Battery Life typically 48 hours in non-alarm condition; 12 hours in alarm condition
Battery Charger battery is continuously trickle charged when instrument is connected to line power and turned on
Construction wall mount aluminum housing with ivory powder coat paint
Size 18.7 x 24.6 x 6.4 cm
Weight 2.1 kg (4.7 lb)

Here is a list of some popular, pre-configured systems utilizing the Model 375 controller. Contact us to receive a quote for a system best meeting all your needs.

Preconfigured Area Monitoring Systems

375/1 0.1 to 9999 uR/hr (internal G-M probe)
375/2 0.1 mR/hr to 1.0 R/hr (internal G-M probe)
375/4 1.0 mR/hr to 10 R/hr (internal G-M probe)
375-9 0.1 mR/hr to 1,000 R/hr (external ion chamber probe)
375-10 1.0 uR/hr to 2,000 uR/hr (Internal NaI probe)

Preconfigured Gateway Monitoring Systems

375P-1000 Dual 7866 cm-3 (480 in-3), PVT 24,000 cpm/uR/hr

Preconfigured Waste Monitoring Systems

375P-336 Dual 2753 in-3 (168 in-3), PVT 12,000 cpm/uR/hr


Ethernet Software
Model 272D Digtial Remote Dislpay