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Technical Articles
Over the years, Ludlum Measurements has written several technical articles in support of our products. These articles cover topics such as troubleshooting and repair tips, calibration techniques, and other information related to radiation detection and instrumentation.
Check Sources
From time to time, we get phone calls from end users of LMI instruments who have questions about check sources that are optional accessories with our instruments. (The exception to the "optional" part is that a check source is standard equipment with gate monitor systems.)
Many of you are familiar with check sources, what they are and how they are used; however, for those of you who are not, here is a short explanation.
Disinfecting Ludlum Instruments and Detectors
In the event that it becomes necessary to disinfect one of our instruments or detectors, please use following the guidelines.
Survey Meters and Detectors
At some point you may wish to use a different detector with your survey meter than the detector the instrument was originally calibrated with. Unfortunately, this can cause issues because not all detectors operate at the same high voltage or use equivalent meter scales. Using a survey meter and a detector that have not been configured to be used together can lead to inaccurate radiation measurements.
Adjusting the High Voltage on LMI Instruments
One of the most common service problems is the maladjustment of the detector high voltage setting. We receive many calls from users who have attempted to trouble-shoot their instrument with a "high Impedance" voltmeter. This usually results with the problem of not being able to adjust the high voltage above 450 V. The reason for this problem is the "high impedance" voltmeter typically has an 11 MΩ output impedance and will overload on resistive loads below 60 MΩ.
Determining Detector Operating Voltage
Many of our customers inquire about the procedure we use to check the operating voltage of scintillation or proportional type detectors. We call this process “to run a plateau”. Hopefully, the following will help to answer a few of these questions.
Troubleshooting Tips
Occasionally, you may encounter problems with your LMI instrument or detector that may be repaired or resolved in the field, saving turnaround time and expense in returning the instrument to us for repair. Toward that end, LMI electronics technicians offer the following tips for troubleshooting the most common problems. Where several steps are given, perform them in order until the problem is corrected. You should keep in mind that the three most common problems are: 1. detector cables, 2. sticky meters, 3. battery contacts.
Connectors
Have you ever really needed an extra probe or cable badly, and after receiving it, found it had the wrong connector?
If the answer is yes, then this problem can be solved with a little help from you.
Calibration Tips: Gas Proportional Detectors
We frequently get questions about our gas proportional detectors, and are glad to offer information on how we "check out" this product. In the following example, we will demonstrate the check-out procedure for the Ludlum Model 43-68 gas proportional detector.
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