Ludlum Model 3 Survey Meter with 44-9 Geiger Probe
0-5000 CPM General-Purpose 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, cable, and batteries.

This particular Model 3 has the general-purpose 0-5000 CPM meter face, Ludlum part number 202-002.

The 202-002 is a versatile count-rate face that works very well with the included 44-9 but is not limited exclusively to that probe model.

These instruments are not simply powered on and checked for a response. Every meter is opened, inspected, cleaned, serviced as needed, adjusted, and thoroughly tested before it is offered for sale.

The meter and probe you receive will be in similar overall condition to the representative set shown in the listing photos.

🔹 Understanding the 0-5000 CPM Face:

CPM means counts per minute. The meter displays the number of radiation events detected by the connected probe rather than displaying an exposure rate or dose rate.

The 0-5000 CPM scale is used together with the Model 3 range selector:

• X0.1 range displays up to 500 CPM
• X1 range displays up to 5,000 CPM
• X10 range displays up to 50,000 CPM
• X100 range displays up to 500,000 CPM

The included Ludlum 44-9 probe detects alpha, beta, and gamma radiation. The displayed CPM value represents the total pulses detected and does not identify the isotope or distinguish between the different types of radiation producing those counts.

CPM is commonly used for contamination surveys, equipment screening, source checks, comparative measurements, and general radiation detection.

The detected count rate can vary based on the type and energy of the radiation, distance, shielding, source geometry, probe efficiency, and other measurement conditions.

This CPM-only face does not display mR/hr, µR/hr, mSv/hr, or µSv/hr. CPM cannot be reliably converted directly into a dose rate without considering the specific detector, isotope, radiation energy, geometry, and calibration conditions.

🔹 Probe Compatibility:

The Ludlum 202-002 face is a versatile, general-purpose CPM face. It works very well with the included Ludlum 44-9 probe but may also be used with several other compatible Ludlum-style probes.

Not every radiation probe is automatically interchangeable. The probe’s required operating voltage, discriminator setting, connector, polarity, and other electrical requirements must be confirmed before connecting a different detector.

The detector probe determines what types of radiation can be detected and the overall sensitivity of the system. The meter face determines how the detected counts are displayed.

The included Model 3 is configured and tested for use with the included Ludlum 44-9 probe.

🔹 Which Meter Face Should I Choose?

Choose this Model 3 with the Ludlum 202-002 face if:

• You want a complete and properly configured Model 3 with 44-9 probe
• You prefer a straightforward CPM count-rate display
• You may want to use the meter with other compatible probes in the future
• You want a versatile, general-purpose survey meter
• You primarily need contamination surveying or general radiation detection

Ludlum Model 3 meters are available with several different meter faces intended for different probes, measurement units, and applications.

If you require quantitative exposure-rate or dose-rate measurements, the meter face, detector, and calibration must be appropriate for the intended radiation and energy range. An energy-compensation filter may also be required depending on the probe and application.

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.

🔹 Condition:

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.

🔹 Complete Inspection and Service:

Each Ludlum Model 3 is individually gone through before shipping. This process includes:

• Meter opened and internal condition inspected
• Exterior and battery compartment cleaned
• Battery contacts removed and cleaned as needed
• Wiring, controls, switches, connector, audio, and meter operation checked
• Necessary repairs and adjustments completed
• High-voltage output checked and adjusted for the 44-9 probe
• Pulse-count accuracy tested and adjusted across every meter range
• 44-9 probe inspected and verified for proper response
• Complete meter and probe combination functionally tested
• Individual testing and verification paperwork prepared

Any problems discovered during this process are corrected before the meter is approved for sale.

🔹 Testing and Documentation:

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:

• Photos of the exact meter and probe assigned to your order undergoing pre-shipment verification
• Photos showing your meter responding to a radioactive source (not included)

The serial number and recorded test results will correspond to the exact meter you receive.

🔹 What’s Included:

• Ludlum Model 3 survey meter with installed Ludlum 202-002 face
• 0-5000 CPM general-purpose count-rate scale
• Ludlum 44-9 alpha-beta-gamma Geiger probe
• Protective probe cover
• Compatible probe cable
• Batteries
• Individual test and verification report
• 1 year functional guarantee

🔹 Ready to Use:

This is a complete general-purpose 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 general-purpose CPM face provides a straightforward indication of detected count rate without suggesting a dose-rate value that may not be valid for the radiation being measured.

This meter and probe will arrive configured, tested together, documented, and ready to use.

🔹 1 Year Functional Guarantee:

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.

🔹 Important Notes:

• No radioactive sources or demonstration materials are included
• The 0-5000 CPM face displays count rate and does not directly display exposure rate or dose rate
• The meter detects radiation but does not identify the isotope producing the response
• The 44-9 detects alpha, beta, and gamma radiation but does not distinguish between them
• CPM cannot be reliably converted directly into dose rate without the correct detector response and calibration information
• Compatibility and setup requirements must be confirmed before connecting a different probe
• Quantitative exposure-rate or dose-rate measurements require an appropriately configured and calibrated meter and detector combination
• Licensed and traceable third-party calibration service is available for an additional fee
• Discounts are available for multiple-unit purchases
• Each instrument is individually photographed and documented during testing and packaging
• A signature may be required at delivery due to the value of the shipment

📦 Shipping and Other Details:

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.