Adjust the pulser negative pulse frequency to provide a better meter deflection of approximately 80% of full scale on the ×100 range. Recalibration is not normally required following instrument cleaning, battery replacement, or detector cable replacement. Removal of the handle will facilitate access to these contacts. If the pulser does not have a high-voltage readout, use a highimpedance voltmeter with at least 1000 megohm input resistance to measure the high voltage. Check the meter reset function by depressing the and ensuring the meter needle drops to 0. Check the 20% scale indication of the Model 3 by reducing the pulser count rate by a factor of 4. Turn the range selector switch to the ×100 position.
This instrument will measure count rates over a range of 0-500,000 cpm. The operator is strongly cautioned to take the following precautions to avoid contact with internal hazardous live parts that are accessible using a tool: 1. Refer to the detector operating manual for specific recommendations. It comes in a variety of measurement ranges and units to support the external radiation detector selected. Maintenance Instrument maintenance consists of keeping the instrument clean and periodically checking the batteries and the calibration. Repeat the above procedure for the remaining lower ranges.
Page 3-1 February 2013 Model 3 Technical Manual Section 3 Size: 16. Connecting a Detector to the Instrument Caution! Check the appropriate regulations to determine required recalibration intervals. U6 is configured as a constant current source to pin 3 of U4. Page 4-2 February 2013 Model 3 5 Technical Manual Section 5 Section Safety Considerations Environmental Conditions for Normal Use Indoor or outdoor use No maximum altitude Temperature range of -20 to 50 °C -4 to 122 °F. For those that have been following my reviews, an important safety feature in Geiger detector meters is an anti-saturation function. The higher the rate, Ludlum Measurements, Inc. Use the links in the side menu to view manuals for our Medical Physics product line and for manuals available in languages other than English.
Multiply the scale reading by the multiplier to determine the actual scale reading. Repeat this process for the ×10, ×1, and ×0. Do not immerse the instrument in any liquid. Alpha and gamma scintillators typically operate from 10-35 mV. The cast aluminum instrument housing with a separate battery compartment and metal handle offer an industrial robustness and quality that promote long-lasting protection and instrument life. The controls may be adjusted with a 0. On a gamma scintillator, visually inspect the crystal for breakage or humidity leakage.
Each range has a front-panel mounted calibration control. The output self-biases to 2 Vbe approximately 1. The discriminator is set by a voltage divider R21 and R23 , coupled to pin 3 of U8. The symbol appears as such: Ludlum Measurements, Inc. Check polarity See marks inside batter lid.
Connect the pulse generator through a 0. If one of these instruments is not available, use a voltmeter with a minimum of 1000 megаohm input resistance. Then use that conversion rate to calibrate other points or scales. This arrangement allows the same current to be delivered to C9 by 1 count on the ×0. The points should be separated by at least 40% of the full-scale value and should be represented by points of approximately equal distance from the mid-point of the scale.
It is acceptable if a calibration graph or chart is provided with the instrument. Meter was put on the pulser and performed well. As always, please call if you encounter difficulty in resolving a problem or if you have any questions. The ranges on the instrument selector switch are multipliers for the meter reading. The unit is operated with two ˝D˝ cell batteries for operation from -20 to 50 °C -4 to 122°F. Bill As usual, I've been taking notes. One model you will see is a Model 3-6 which is a version that was built for a Department of Energy contract.
A Model 3 can have multiple scales corresponding to different detectors. R38 and C28 provide filtering. For example, 25% and 75%, or 20% and 80% could be used. Note: In the event that any reading is not within 10% of the true value on any scale after any of the above calibration methods is performed, a reading within 20% of true value shall be acceptable. I'll do some sort of compilation to post here and I'm working with a friend of mine to do a separate web site that will have all the reviews as well.
Calibration Controls: Recessed potentiometers that are used to calibrate the individual range selections and allow for high-voltage adjustment from 400 to 1500 volts. Allow 20 s for recovery. Plug in the 2-pin connector if necessary. Page 2-2 February 2013 Model 3 Technical Manual Section 2 The detector cable can be a source of problems. Also provide appropriate warning labels to ensure careful handling. Gamma762 and mm38, thanks for the encouragement. Meter Drive Pulses from pin 6 of U9 charge capacitor C9.