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Model 26-1 Series

Integrated Frisker

Model 26-1 Part Number: 48-3965
Model 26-1DOSE Part Number: 48-4007

Features

Integrated, Lightweight Ergonomic Design
High-Impact Plastic with Water-Resistant Rubber Seals
Employs Standard 15.51 cm² GM Pancake Detector
Displays in mR/hr, µSv/h, dpm, Bq, cpm, or cps
Dead-Time Correction (DTC) Allows Gamma Measurements Up to 500 mR/hr or Up to 1999 µSv/h
Simple Three-Button Operation
Count Rate, Exposure, Dose, and Counting Alarms
Automatic Display Backlight
Bright Red, Flashing Alarm LED
Includes Wrist Strap, Detector Cover & Lanyard

The Model 26-1 Integrated Frisker is designed to simplify the process of detecting radioactive contamination on people and objects. Unlike other meter and detector combinations that require two-handed operation, this instrument combines the meter electronics and detector in a single, easy-to-use tool. Its design incorporates a 15.51 cm² (2.4 in²) GM pancake detector, an easy-to-read LCD screen, an ergonomic handle, and a simple three-button interface to allow one-handed operation.

Three modes of operation are available — RATE, MAX, and COUNT — which can be selected by pressing the MODE button. RATE mode displays the current count, exposure, or activity rate. MAX mode captures the highest count, exposure, or activity rate detected; this is useful for finding a peak rate or for frisking when the display is not visible. COUNT mode allows the operator to perform a survey for a preset amount of time; depending on the chosen units, the count result can be a scaler count, a time-averaged rate, a time-averaged exposure or dose rate, or an integrated exposure or dose. Measurements can be displayed in units of cps, cpm, dpm, Bq, mR/h, or μSv/h. The user can switch between two sets of chosen units (primary and secondary) for RATE and MAX modes by pressing the UNITS button.

Other features include an auto-ranging and backlit LCD screen, “click” audio (which can be silenced), and user-settable count rate and scaler alarms. The instrument body is made of high impact plastic and water-resistant construction allows the instrument to be used outdoors. A wrist strap and lanyard are included for keeping the instrument close and secure. The instrument is powered by two alkaline AA batteries with a battery life up to 1000 hours.

Ambient Dose Equivalent Filter

The GM pancake detector has a significant over-response to gamma energies between 20 - 150 keV (see Energy Response Graph on Graphs tab below), which produces dose measurement errors. Ludlum offers an ambient dose equivalent filter that flattens the detector’s energy response to within ± 20% referenced to ¹³⁷Cs (662 keV) over the energy range of 20 keV to 1.2 MeV. The filter simply snaps on over the detector window when dose measurements are required, and is easily removed when not needed. The dose filter is included with the Model 26-1DOSE (PN 48-4007), or it is available separately as an option (PN 2002-1050).

Specifications

Detector	Pancake GM detector, stainless steel screen (79% open)
Window Area	Active: 15.51 cm² (2.4 in²) Open: 12.26 cm² (1.9 in²)
Efficiency	Alpha ²³⁹Pu: 11% Beta ⁹⁹Tc: 14% ³²P: 32% ¹⁴C: 2% ⁹⁰Sr/⁹⁰Y: 22% ¹²⁵I: 0.2% Gamma 5.5 cps per μSv/hr (3300 cpm per mR/hr) (¹³⁷Cs) ^99mTc : ≤ 1%
Display	3½ digit LCD with large 12.7 mm (0.5 in.) digits, low-battery indicator, MAX, ALARM Units: (k)cps, (k)cpm, (k)dpm, (k)Bq, mR/hr, µSv/h
Range	0.00 cps to 19.9 kcps 0 cpm to 999 kcpm 0.00 Bq to 19.9 kBq 0 dpm to 999 kdpm 0.00 to 500 mR/h 0.00 to 1999 µSv/h
Linearity	±10%
Backlight	Built-in ambient light sensor automatically activates low-power LED backlight, or may be configured for 'Continuous On' (will reduce battery life)
Controls	ON / OFF / QUIET: Press to turn ON; Tap to alternate between click audio and QUIET; Hold for OFF MODE: Alternates between RATE (count rate), MAX (captures peak rate), and COUNT (preset count time from 0 to 20 min.) UNITS: Changes units between count rate (cpm, cps), dose/exposure (µSv/h, mR/hr), or activity (dpm, Bq)
Response Time	User-selectable from 1 to 60 seconds, or Auto-Response Rate FAST or SLOW
Resolving Time	Approximately 110 µs as defined by IEC 60325
Alarms	Count rate and scaler alarm setpoints adjustable over the display range
Overload Protection	High rate saturation protection, indicated by flashing display and audio alarm, prevents false display of lower count rates
Loss of Count Protection	After 60 seconds of no pulses from detector, unit will flash a zero reading and the alarm audio will be triggered
Click Audio	Greater than 60 dB at 0.6 m (2 ft)
HV Testpoint	Accessible by removing battery cover, allows HV measurement and pulse injection for calibration using optional cable (PN: 8303-1044)
Temperature Range	-20 to 50 °C (-4 to 122 °F) May be certified for operation from -40 to 65 °C (-40 to 150 °F)
Environmental Rating	NEMA 3, IP 53
Power	Two “AA” batteries
Battery Life	Approximately 1000 hours of operations (as low as 500 hours with backlight configured for 'Continuous On'), 16-hour low battery warning
Construction	High-impact plastic with water-resistant rubber seals and separate battery compartment
Distance from Surface Plane to Screen	0.32 cm (0.125 inch)
Size (H x W x L)	4.6 x 6.9 x 27.2 cm (1.8 x 2.7 x 10.7 in.)
Weight	0.45 kg (1.0 lb)

Options

Option	Description	Part Number
Dose Filter	Flattens the GM detector energy response to within ± 20% referenced to ¹³⁷Cs (662 keV) over the energy range of 20 keV to 1.2 MeV. Included with Model 26‑1DOSE.	2002-1050 (dose filter only) 4519-041-02 (dose filter with tether)
Protective Cover with Tether	Adds tether to the detector protective cover to keep attached to instrument when cover is not in use.	4519-041
Headphone Jack	Adds headphone jack to instrument.	4498-538
Canvas Holster	Canvas holster with belt clip for Model 26 Series instruments.	2312577
Model 180-28	Sample holder for Model 26-Series friskers.	47-3948
Calibration Cable	Allows HV measurement and pulse injection into any Model 26 family of instruments (excluding the Model 26S) from 2019 and later. 99 cm (39 in.) long, C to test pin.	8303-1044
Extendable Pole	A lightweight pole with 5 telescoping sections and an adjustable clamp to hold a Model 26 Series Frisker. Useful to access high, low, or other hard to reach places. Length: 0.55 m (1.8 ft) collapsed, 1.5 m (4.92 ft) fully extended	4519-077
Transport & Storage Case for Model 26 and Extendable Pole	Rugged, waterproof, airtight, hard-shell case with dense foam padding to hold Model 26 and extendable pole.	2311064