0-6.6K CPM / 0-2 mR/hr Combination Face | Fully Serviced and Tested | 1 Year Functional Guarantee
This listing is for one used Ludlum Model 3 survey meter with a Ludlum 44-9 alpha, beta, and gamma Geiger probe, protective probe cover, compatible BNC probe cable, and batteries.
This particular Model 3 has the Ludlum 202-608 combination meter face with both a 0-6.6K CPM count-rate scale and a 0-2 mR/hr gamma exposure-rate scale.
This set uses BNC detector connections and includes the compatible BNC cable for the meter and 44-9 probe combination supplied.
The 202-608 face is specifically designed around the typical Cesium-137 gamma response of the Ludlum 44-9 probe, making this an excellent choice for someone who intends to primarily use the meter with the included 44-9.
The meter and probe you receive will be in similar overall condition to the representative set shown in the listing photos.
This meter face provides two ways to display the response from the included Ludlum 44-9 probe:
The CPM scale can be used when detecting alpha, beta, or gamma radiation. It is commonly used for contamination surveys, equipment screening, source checks, and general radiation detection.
The mR/hr scale is based specifically on the typical response of a Ludlum 44-9 probe to Cesium-137 gamma radiation. It should only be considered reasonably representative when measuring Cesium-137 with the included 44-9 probe.
Even when measuring Cesium-137, the displayed mR/hr value should be treated as a rough screening estimate unless the complete meter and probe combination has received a traceable exposure-rate calibration by an appropriate calibration provider.
An unfiltered Ludlum 44-9 has an energy-dependent gamma response. When measuring isotopes other than Cesium-137, the indicated mR/hr value may be significantly higher or lower than the actual exposure rate.
For more accurate measurements across a broader range of gamma energies, an appropriate energy-compensation filter must be installed on the probe. The meter, probe, and filter must then be calibrated together with the filter installed.
Unless specifically stated otherwise, an energy-compensation filter and isotope-specific exposure-rate calibration are not included with this set.
The mR/hr scale must not be used to interpret alpha or beta measurements. Alpha and beta responses should always be evaluated using the CPM scale.
The Model 3 range selector extends the measurement range of the meter face using the X0.1, X1, X10, and X100 multiplier positions.
Choose this Model 3 with the Ludlum 202-608 combination face if:
Ludlum Model 3 meters are available with several different meter faces intended for different probes, measurement units, and applications.
This meter may be capable of operating other compatible probes with similar electrical requirements. However, the mR/hr scale is specifically matched to the typical Cesium-137 response of the 44-9 and generally will not provide a valid exposure-rate reading with a different type of detector.
The CPM scale may still be used with another probe when the detector and meter settings are compatible.
For quantitative exposure-rate or dose-rate measurements involving unknown isotopes or a broader range of gamma energies, a properly energy-compensated and calibrated instrument should be used.
If you are unsure which meter face or probe combination best fits your intended use, please contact us before purchasing. We will be happy to help you select the appropriate setup.
These are used professional instruments and will show normal cosmetic wear from their previous service. This may include scratches, scuffs, minor paint wear, small dings, or other signs of use.
The unit photographed was intentionally selected to represent the average condition of our standard inventory. It was not selected because it was the nicest or worst unit available.
Cosmetic wear does not affect the guaranteed operation of the instrument.
More heavily discounted units may also be available with substantial cosmetic issues such as exterior corrosion, larger dents, extensive paint loss, peeling paint, or heavier wear. These units receive the same functional testing and verification but are discounted based on appearance.
Please contact us before purchasing for current availability, photos, and pricing on units with heavier cosmetic wear.
Each Ludlum Model 3 is individually gone through before shipping. This process includes:
Any problems discovered during this process are corrected before the meter is approved for sale.
Pulse-rate accuracy is tested and adjusted through all meter ranges using a Ludlum Model 500 pulser with current calibration and NIST traceability. This is the same type of pulse verification equipment used by Ludlum for instrument testing and calibration.
Documentation supporting the calibration of the Ludlum Model 500 is available upon request.
The high-voltage output is checked and adjusted to the recommended 900 V operating setting for the Ludlum 44-9 probe.
After the electronic meter testing is completed, the 44-9 probe is connected and verified for proper response using a known check source.
A printed test report is included with every meter. This report documents the individual results obtained while testing your specific instrument and will be similar to the example report shown in the listing photos.
The included report documents electronic pulse-rate testing, high-voltage verification, and functional response testing. It is not an isotope-specific exposure-rate or dose-rate calibration certificate.
Before shipping, you will receive:
The serial number and recorded test results will correspond to the exact meter you receive.
This is a complete radiation survey package capable of detecting alpha, beta, and gamma radiation.
The Ludlum Model 3 is a rugged, industry-standard survey meter. The Ludlum 44-9 pancake-style Geiger probe is widely used for contamination surveys, equipment screening, laboratory work, industrial applications, and general radiation detection.
The combination face allows the 44-9 response to be viewed in CPM while also providing a rough Cesium-137 gamma exposure-rate reference in mR/hr.
The mR/hr indication should not be considered an accurate dose-rate measurement for other isotopes unless an appropriate energy-compensation filter is installed and the complete meter, probe, and filter assembly is calibrated together.
This meter and probe will arrive configured, tested together, documented, and ready to use.
Every set is guaranteed to arrive fully functional and ready to use.
This instrument includes a 1 year functional guarantee from the date of delivery. The guarantee covers functional failure of the meter, probe, or included cable during normal use.
The guarantee does not cover abuse, misuse, dropping, crushing, moisture intrusion, battery leakage, improper storage, contamination, unauthorized repairs, tampering, modification, damage to the probe window, or damage caused by connecting incompatible equipment.
These are precision scientific instruments. Rough handling or abuse will void the guarantee.
Orders ship promptly after the exact instrument has been tested, documented, and approved for shipment.
International and non-contiguous U.S. buyers should contact us before purchasing to confirm shipping costs. The automated shipping calculator may not always provide an accurate estimate.
Please feel free to contact us with questions, requests for additional photos, quantity inquiries, help selecting the correct meter face, or questions about discounted units with heavier cosmetic wear.
Limited inventory. Availability is subject to prior sale.