Model 9-4RF

RF-Immune Air Ion Chamber Survey Meter

Part Number: 48-4338

Features

5-Range Ion Chamber
Ranges: 0 to 500 mSv/h (0 to 50,000 mR/hr)
1000 mg/cm² Retractable Beta Shield
RF Immunity
PC-Controlled Calibration
Low-Battery Warning
High-Background Zero Capability
Automatic Temperature & Pressure Compensation
Adjustable Shoulder Strap Included

The Ludlum Model 9-4RF is a rugged air ionization chamber for performing beta-gamma dose rate measurements over a five-decade span ranging from 0 to 500 mSv/h (0 to 50,000 mR/hr). This variant of the Model 9-4 has improved components and shielding to pass RF susceptibility tests at military levels up to 18 GHz and is an improved replacement for old Model 440RF/D survey meters.

The ion chamber automatically compensates for changes in temperature and pressure. The chamber wall (including the instrument case) is 1000 mg/cm². A 1000 mg/cm² retractable beta shield allows beta measurement with a 7 mg/cm² window.

The six-position selector switch selects Off, x10k, x1k, x100, x10 and x1. Other controls include an On/Off switch for a meter light, reset and battery test buttons, and a zero adjustment knob. An adjustable shoulder strap (included) provides a convenient and comfortable mode to carry the instrument during surveys.

The Model 9-4RF is equipped with a serial interface for calibration. An optional calibration kit supplies the necessary interface cable, software, calibration can, pressure pump, and serial-to-USB converter.

Specifications

Detector

Detection Range	0 to 500 mSv/h (0 to 50,000 mR/hr)
Energy Response	Within 20% of true value from 40 keV to 2 MeV
Linearity	Reading within 10% of true value
Response Time	Approximately 5 seconds for 90% of final meter deflection on the x1 and x10 scales, and 3 seconds on the x100, x1k and x10k scales
Chamber Volume	220 cm³ (13.4 in³)
Chamber Construction	Carbon coated acrylic
Window	7 mg/cm² metalized polyester; with slide open, allows gamma detection to 6 keV
Window Area	40 cm² (6.2 in²) (31.5 cm² [4.9 in²] open with optional 79% open screen)
Side Wall	1000 mg/cm² aluminum and acrylic
Beta Shield	Retractable 1000 mg/cm² phenolic slide with side button control
Beta Response	Factor of 4.8 difference between window open and closed measurements when exposed to a uranium slab

Instrument Controls

Range Selection	Instrument Off, x10k, x1k, x100, x10, x1
Zero Adjust	One-turn potentiometer to zero reading
Battery	Pushbutton used to check battery capacity
Reset	The RESET circuit grounds the chamber and opens the chamber connection to the electrometer. This causes a hard upscale transient on the x1 scale. Hold the RESET down for 4 seconds to allow the transient to decay. When the RESET switch is opened, the chamber is reconnected to the electrometer and a hard downscale transient will occur. Allow 20 seconds for recovery.
Display Light	Toggles a white LED display On/Off
Calibration	Digitally set via USB to serial computer interface, stored in non-volatile memory

Meter

Meter Dial	0 to 5 mR/hr, BAT TEST
Meter	6.4 cm (2.5 in.) arc, 1 mA, pivot-and-jewel suspension
Compensation	Automatically corrects for temperature and pressure changes in atmosphere
Pressure Compensation Range	70 to 106 kPa (20.7 to 31.3 inHg)
Temperature Range	-20 to 50 °C (-4 to 122 °F), temperature compensation maintains calibration within 15% of 25 °C (77 °F) reading
Power	2 each “D” cell batteries housed in a sealed externally accessible compartment
Battery Life	400 hours
Construction	Cast and drawn aluminum with beige powder coating
Size (H x W x L)	23.4 x 8.9 x 21.6 cm (9.2 x 3.5 x 8.5 in.) including instrument handle
Weight	1.9 kg (4.2 lb) including batteries

Options

Option	Description	Part Number
Lighted Handle	Handle with LED to illuminate the instrument display.	4464-154
Transport & Storage Case - Medium	Rugged, dust- and waterproof transport and storage case.	2311063
Model 9-4 Calibration Kit	Includes special instrument can, pressure calibration kit, all necessary cables, and control software.	4293-676-02