Ludlum - Model 26-1 Frisker

Ludlum Model 26-1 Digital Contamination Frisker

The Ludlum Model 26-1 incorporates electronics and a time-tested GM (Geiger-Mueller) detector in an ergonomically designed, ruggedly-constructed, and water-resistant housing. The integrated unit is therefore cable-less thereby simplifying the process of frisking people and objects. The optimized configuration includes a standard 15 cm² GM pancake, loud audible “click” output, and large auto-ranging LCD display with automatic LCD backlighting. Model 26-1 has the addition of a Units button that can display measurements in terms of mR/hr, µSv/h, dpm, or Bq. These features are combined in one convenient package making it easier than ever to detect alpha/beta contamination and measure gamma fields on personnel and objects.

Operation of the Model 26-1 is kept simple through the use of just three buttons that are strategically placed for one-handed operation. Three modes of operation RATE, MAX, and COUNT, are available. The RATE mode will display current radiation levels in terms of rate. MAX mode captures the highest rate detected so it is possible to determine a peak rate during frisking operations when the display is not visible. COUNT mode allows the operator to perform a survey for a predetermined time. The user-selected units can display results in a measurement of scaler counts, activity (disintegrations), time-averaged rates, or even accumulated dose. In addition, the optionally-available energy-compensation filters can correct the energy response for exposure or ambient equivalent dose.

Low-power circuitry means two standard “AA” sized batteries deliver hundreds of hours of instrument operation. The parameters may be protected via internal dipswitch, or the calibrator may allow the user to adjust them. Other features include a backlight triggered by low-level ambient lighting  (may be configured for “Continuous On” operation) and a click’ audio that may be silenced for both RATE and MAX modes.



Indicated Use Contamination monitoring in Bq/DPS

Alpha: 11% for Pu-239

Beta: 18% for Tc-99, 32% for P-32, 2% for C-14, Sr-90 22%

Resolving Time Approximately 110 microseconds as defined by IEC 60325
Threshold Fixed at 40 mV to 10 mV
Alarms Count rate and scaler alarm setpoints adjustable over the display range
LCD Display
3½ digit LCD with large 12.7 mm (0.5 in.) digits, cpm, cps, low battery indicator
Response Time
User-selectable from 1 to 60 seconds, or automatic FAST or SLOW
Temperature Range -20 to 50 °C (-4 to 122 °F), may be certified for operation from -40 to 65 °C (-40 to 150 °F)
Power Two "AA" Cell Batteries
Battery Life Typically 1000 hours with alkaline batteries
Size 4.6 x 6.9 x 27.2 cm (1.8 x 2.7 x 10.7 in.) (H x W x L)