Survey Meter Operation

Ludlum - Model 3
with 44-9 GM Pancake Probe
The Ludlum Model 3 Survey Meter with Model 44-9 GM Pancake Probe detects alpha, beta and measures gamma radiation levels form 0-200 mR/hr. It is typically used to measure lower levels of radiation, and detects ion contamination levels. Its size and shape provide easy handling for surveying personnel and equipment. The pancake detector is intended to be used only when surveying for contamination. The detector is housed in an aluminum casing; the thin mica window of the detector is protected by a stainless steel screen. The GM tube can be removed for replacement if necessary.
Suggested Operating Procedures - Ludlum Model 3
1. Attach the probe to the survey meter. 2. Insert fresh "D" cell batteries in the instrument, observing polarity. 3. Check the battery strength by turning the selector switch to the BAT position. The needle should jump to the BAT TEST area. 4. Turn the selector switch to the x10 range, and place the probe against a check source. The instrument should give a reading. 5. Move the selector switch to view an exponential reading. 6. Adjust the response control by flipping the toggle switch to F (fast) or S (slow). The response should be adjusted to get the most desirable compromise between response speed and meter fluctuation.



Ludlum Model 2241-2 Survey Meter
The Model 2241-2 is a portable microprocessor-based digital Scaler/Ratemeter designed for use with a variety of detector types for measurement of ionizing radiation. The data is presented on a 4-digit (6 digits while in the scaler mode). Liquid Crystal Display (LCD) with a moving decimal point. A three-position switch labeled OFF/RATEMETER/SCALER selects the desired operating mode for the instrument. A locking toggle switch labeled DET 1 and DET 2 allows for a quick change of operating parameters between detectors.
The Model 2241-2 features adjustable alarm set points for the RATEMETER and SCALER operating mode. The RATEMETER mode has two alarm indications. The first level alarm is indicated by the word ALERT on the LCD. The second level alarm is indicated by by the word ALARM and a continuous audible tone. The SCALER alarm condition will also display the word ALARM and produce the same audible tone. Both of the audible alarms can be silenced/acknowledged by depressing the RESET switch. Alarm parameters are set during instrument calibration. The Unit is operated with two-"D" cell flashlight batteries. The unit body is made of cast and drawn aluminum with polyurethane paint which aids in decontamination of surfaces.
Detector Types:
The Ludlum Model 2241-2 can operate with a variety of detectors, but will most commonly be used with the Model 44-9 (pancake) and Model 44-38 (hotdog) external GM detectors.
Model 44-9 (Pancake) Probe
Instrument Operating Range:
The instrument provides auto-ranging form 0 uR/hr to 9999 R.hr, or 0 cpm to 999 kcpm, depending on which detector is attached. (u=micro = one one-millionth; k-kilo = one thousand)
Types of Radiation Detected
When operated with the Model 44-9 (pancake/frisker) detector, the instrument is capable of detecting alpha, beta, gamma, and x-ray radiation. When operated with the Model 44-38 (hotdog) external GM detector, the instrument is capable of detecting beta, gamma, and x-ray radiation. The size and shape of the 44-9 provides easy handling for surveying personnel and equipment. The pancake detector is intended to be used only when surveying for contamination. The detector is housed in an aluminum casing; the thin mica window of the detector is protected by a stainless steel screen. The GM tube can be removed for replacement if necessary.
Model 44-38 (Hotdog) Probe
The Ludlum Model 44-38 GM (Hotdog) Detector will detect beta and gamma radiation. The hotdog detector is intended to be used when surveying for direct radiation versus contamination. The GM tube is protected by a slotted metal housing assembly. The detector housing incorporates a rotary shield which may be ued to differentiate between beta and gamma radiation. With the detector shield closed, beta radiation is blocked out and only gamma radiation is detected. With the rotary shield open, both beta and gamma radiation can be detected. The beta dose contribution from a measurement can be determined by subtracting the reading taken with the rotary shield closed from the reading takein with the rotary shield open ( open window closed window).
Operating Controls:
Off/Ratemeter/Scaler Switch: A three-position rotary switch which applies power to the instrument and selects the RATEMETER or SCALER counting modes. DETector Select Switch: A protected toggle switch that toggles between DET 1 and DET 2 parameters. The pull-and-change toggle switch is designed to protect against inadvertent changes. The switch is to be set to DET 1 when the pancake probe is attached; units displayed will be kcpm. Set the switch to DET 2 when the hotdog probe is attached; units displayed will auto range from uR/hr to mR/hr to R/hr. AUD ON/OFF Switch: The audio may be silenced or enabled via this toggle switch. The audible ALARM is independent of the AUD ON/OFF switch. F/S (Fast/Slow) Response Switch: A two position toggle switch with selects Fast or Slow counting response time. The fast response setting should be used when performing an initial survey or when trying to locate sources of radiation. Switch to slow response when more accurate measurements are needed ( e.g. for official measurements). Light (LCD Backlight): A pushbutton switch, when depressed, illuminates the LCD for a pre-programmed period of time. RESET Pushbutton Switch: In the non-alarm condition, depressing the RESET switch resets the Ratemeter display to the minimum display readout. In an alarm condition, depressing the RESET will silence the audible alarm; depressing the RESET Switch a second time will reset the Ratemeter alarm and/or alert condition. The Scaler alarm can only be reset by depressing the Scaler to start the counting cycle. Scaling time is set during instrument calibration and can be set from 1 to 999 seconds. Depressing the Count switch after a Scaler ALARM will reset the Scaler display to "0" resetting the alarm condition.
Suggested operating Procedure for the Ludlum Model 2241-2
1. Check the Calibration expiration date, if the instrument calibration is past due, do not use the instrument. 2. Visually inspect the instrument for damage. If there is damage which impairs the use of the instrument do not use the instrument. 3. Ensure the Model 2241-2 power switch is in the OFF position. Open the battery lid and install two "D" size batteries. Note (+) (-) marks on the inside of the lid. Match the battery polarity to these marks. Close the battery box lid. 4. Connect either the hotdog or pancake detector to the instrument and position the DETector select switch accordingly. 5. Turn the OFF/RATEMETER/SCALER switch to the RATEMETER position. The display will go through a start-up sequence. The display will show all 8s with decimal points. (see figure at right) Check to make sure all segments of each number display are functioning. 6. After the start-up sequence is complete, the unit will show the typical operating screen with the display auto ranging to the current radiation level in either R/hr or kC/m, depending on which position the DETector select switch is in. 7. Expose the detector to an external check source if the background count is too low to generate a display reading. Switch the AUD ON/OFF to the ON postion and confirm the external speaker produces and audible click. Normal operating model should be with the AUD ON/OFF toggle switch in the ON position. 8. Switch to the Scaler position. Depress the Count switch located in the ind of the carrying handle to start the count cycle. The word "COUNTING" should be visible in the display during the count cycle and should disappear at the end of the preset count time. Count time is set during instrument calibration, ans is typically set for six seconds. 9. Depress and release the LIGHT switch. The backlight located behind the LCD should illuminate. 10. Select the desired F/S, AUD ON/OFF, and RATEMETER or SCALER parameters and proceed to use instrument.


Ludlum Model 14C - Survey Meter
The Ludlum Model 14c is designed to be operated with an external GM detector for X0.1 through X100 ranges and is equipped with an internal GM detector for X1000 range. The instrument provides an overall range of 0-2000 mR/hr
Types of Radiation detected.
Depending on which external GM detector is attached, the instrument is capable of detecting alpha, beta, gamma and x-ray radiation. The internal GM detector, operated on the X1000 scale only, will detect gamma and x-ray radiation.
Operator-adjustable controls
The range mulitplier selector switch is a 6-position marked OFF, X1000,X100,X10,X1X0.1. Moving the range selector switch to one of the range mulitpolier postions provides the operator with an overall range of 0-2000 mR.hr. Multiply the scale reading by the mulitiplier for determining the actual scale readings. Audio ON-OFF toggle switch: in the ON position, the switch energizes the speaker, located on the left side of the instrument. The frequency of the clicks is relative to the rate of the incoming pulses. The higher the rate, the higher the audio frequency. The audio should be turned OFF, when not required, to reduce battery drain Fast-Slow toggle switch: selecting the fast, "F", position of the toggle switch provides 90% of final meter reading in four seconds. In slow, "S", position, 90% of final meter reading takes 22 seconds. Set on "F" for fast response and large meter deviation. "S" position should be used for slow response and damped meter deviation. The fast response setting should be used when performing an initial survey or when trying to locate sources of radiation. Switch to slow response when more accurate measurements are needed (e.g, for official measurements). RES button: when depressed, provides a rapid means todrive the meter to zero. BAT check: when depressed, provides a visual means of checking the battery charge status. The instrument must be turned on to perform this function.
Operation of internal/external detector:
The internal GM detector is operational on the X1000 scale only. The attached external GM detector is operational for scale multiples X0.1, X1, X10, X100.
Specific characteristics/limitations:
The Ludlum Model 14C is a portable survey instrument designed for operation with a GM detector that operates on two standard "D" cell batteries. The unit body is made of cast-aluminum, including the meter housing. The instrument can operate with either a thin wall GM detector or a pancake GM detector. The Ludlum Model 14c is also equipped with an internal high range detector that is operational only when the meter is on the X1000 range. With two "D" cell batteries, the Ludlum Model 14c is set for 900-volt GN tube operations from 32 F to approx. 150 F, either very fresh alkaline batteries or rechargeable Nickel-cadmium (NiCd) batteries may be used.
Instrument Maintenance:
Never store the instrument over 30 days without removing batteries. Although the instrument will not be affected, battery failure can occur. Follow your state's requirements for instrument calibration, Annual instrument calibration is recommended.
Suggested Operating Procedure for the Ludlum Model 14c:
1. Check the calibration expiration date, if the instrument calibration is past due, do not use the instrument. 2. Visually inspect the instrument for damage. If there is damage which impairs the use of the instrument do not use the instrument.. 3. Ensure the Model 14c power switch is in the OFF postion. Opern the battery lid and install two "D" size batteries. Note (+)(-) marks on the insde of the lid. Match the battery polarity. If the response falls below the accepted range, install new batteries. 4. Turn the instrument range switch to X1000. Depress the button on the face of the instrument labeled BAT. The meter should deflect to the battery check position of the meter scale. If the meter does not respond, recheck to be certain that the batteries have proper polarity. If the response falls below the accepted range, install new batteries. 5. Utilizing the externally attached detector, move the range switch to the lower scales until a meter reading is indicated. The toggle switch labeled F-D should have fast response in "F" position, slow response in "S" position. . Place the toggle switch in the "F" position to start. Expose the external probe to a radiation check source. The speaker should click with the audio switch in the ON position. Visually inspect to ensure that the readout of the instrument also responds. 6. Press the RES switch, The meter should zero. 7. Proceed to use the instrument.