UK Shipping included; overseas buyers see important note below*

Here's a very rare opportunity to own a classic vintage British-made Geiger counter. The Mini Instruments models 5.10 and 5.40 have been a popular choice in education, industry and research for several decades and we have a small stock of fully refurbished instruments ready for dispatch.

Although they have been around for a few years they have proved to be extremely robust and reliable and continue to work as well as they did when they were made and compare favourably with, and even exceed the performance, durability, refinement and ease of use of many modern instruments.

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WE ALSO BUY SERVICE, REPAIR & CALIBRATE MINI MONITORS

                                           TO CONTACT US PLEASE SEE BELOW FOR MORE INFO

The key feature, still used on current Mini-Monitor 900s, is the large and very easy to read moving coil meter, with a clever logarithmic scale. In a nutshell this means there is no need for a range switch and it can accurately display (in counts per second or cps) both high and low level readings (from normal background, to ‘get the hell out of there’…). 

5.40 'bare bones' models are not normally supplied with probes. The very wide range of HT voltage adjustment (between 450 and 1300 volts) makes them compatible with most probes types, up to and including Scintillation detectors. For added convenience the voltage adjustment preset is mounted on the outside of the case. Probes are available, use Contact Us at the bottom of the page if you need more details. 

KEY FEATURES

• Internal speaker (with mute switch)
• LED ‘event’ flasher (most models)
• Audio output socket
  
• DC supply socket
  
• Detachable probe
  
• Adjustable HV supply (approx 250 - 700 volts & 300 - 1200 volts depending on model)
  
• Battery Check function
  
• Sturdy, compact metal case with carry handle and probe cradle
  
• Convenient ‘curly’ probe cable lead
  
• Portable operation with long battery life
• Calibrated prior to dispatch
• Operating Manual (generic) with calibration info and circuit diagram included

As far as performance, reliability and ease of use are concerned the two models are almost identical (Type 5.10 cases may have rounded or square corners). The only significant difference is that the Type 5.10's probe supply is adjustable from around 250 to 750 volts whilst the 5.40 goes from 330 to 1300 volts. The result is a highly versatile instrument, capable of using a wide range of probes and suitable for a variety of specialist and non-specialist applications. (The operating manual includes full details of how to carry out HV adjustments).

Refurbishment begins with a complete strip down. Where necessary cases are taken back to bare metal, primed and re-sprayed using top quality paint to give them a fresh new look. (Custom colours and finishes on request,for details use Contact Us at the bottom of the page). 

All instruments are fully portable, powered by internal battery pack(s) requiring 8 or 12 standard 1.5 volt AA cells (see item description for specifics). Alternatively they can be used as bench instruments as we’ve fitted a DC socket for a mains adaptor (12 - 18 volts). All models have TNC connectors fitted (case and cable), making it a simple matter to exchange probes. We’ve installed an LED indicator as an event 'flasher'. An audio output socket (standard 3.5mm jack) has also been added, so they can be used with headphones, connected to an amplifier, or a PC, for data logging or analysis.

Prior to shipping every instrument is tested (not a single failure or return so far!), the HV adjusted and the unit pulse-calibrated, according to manufacturer's protocols. A Calibration Check Certificate is provided.
 

CURRENT STOCK

5.40/BB
£300.00 inc UK Shipping

Probe Type:                            Not supplied (TNC socket fitted)
Sensitivities:                            n/a
HT voltage:                             Variable approx 450 to 1300 volts
Sensitivities:                            n/a
Features:                                 external HT adjustment (see inset pic)
Applications:                          Scintillation probes
Power Requirements:            12 x 1.5-volt AA cells & AC adaptor
Condition:                                  A

5.10/ZP14 (1)
£380.00 inc UK Shipping

Probe Type:                               ZP1400 mica end window GM tube
HT voltage:                                Variable approx 350 to 700 volts
Sensitivities:                               Alpha, Beta, Gamma & X-Ray
Applications:                             detection, monitoring, contamination control
Power Requirements.               12 x 1.5-volt AA cells & AC adaptor
Condition:                                    A-

5.10/ZP14 (2)
£380.00 inc UK Shipping

Probe Type:                               ZP1400 mica end window GM tube
HT voltage:                                Variable approx 350 to 700 volts
Sensitivities:                              Alpha, Beta, Gamma & X-Ray
Applications:                            detection, monitoring, contamination control
Power Requirements.              12 x 1.5-volt AA cells & AC adaptor
Condition:                                   A-

5.10/ZP14 (4)
£380.00 inc UK Shipping

Probe Type:                                ZP1400 mica end window GM tube
HT voltage:                                 Variable approx 350 to 700 volts
Sensitivities:                                Alpha, Beta, Gamma & X-Ray
Applications:                             detection, monitoring, contamination control
Power Requirements.               12 x 1.5-volt AA cells & AC adaptor
Condition:                                    A-

5.10/SBT11
£390.00 inc UK Shipping

Probe Type:                               32 x 18mm mica end window pancake type GM tube
Sensitivities:                               Alpha, Beta, Gamma & X- Ray 
HT voltage:                                Variable approx 400 to 1200 volts
Aplications:                               detection, monitoring, contamination control
Power Requirements.               12 x 1.5-volt AA cells & AC adaptor
Condition:                                    A

*Very Important Stuff For Overseas Buyers:
The prices shown are for UK buyers and inclusive of delivery to mainland UK addresses. Overseas buyers should contact us before ordering for shipping options, which vary according to location. Please also note that this item may be prohibited or restricted in some countries.

** Please note that these units may have been in service for several years so there might be some slight marking (scuffs, small scratches, etc.) on the meter face. There may be other cosmetic blemishes; however these are generally minor in nature.