Mini Monitor 900 Series Geiger Counters and Ratemeters, designed and  manufactured in the UK by Mini Instruments Ltd (now owned by Thermo Electron/Scientific, also sold under Morgan & Fisher brand names) are amongst the most highly-respected radiation and monitoring instruments in use today.

OVERSEAS CUSTOMERS PLEASE READ THIS FIRST. PRICES SHOWN ARE FOR UK CUSTOMERS ONLY. INTERNATIONAL SHIPPING IS EXTRA AND WILL BE APPLIED DURING THE CHECK OUT PROCESS.

Over the years Mini Monitor 900s have earned an excellent reputation for reliability, performance, versatility, ease of use and value for money. The 900 series continues to be a popular choice in education, research, medicine, industry and amongst environmentalists and enthusiasts. We stock a wide range of pre-owned instruments, all thoroughly tested, checked and calibrated and where necessary, refurbished to a high standard. Here’s just a brief outline of the key features:
 

• Fully Tested and Calibrated prior to dispatch*

• Large, logarithmic meter, accurately displays both very low and high levels 

• Portable & bench operation (mains adaptor or 6 x AA cells)

• Battery life 300 hrs (typical, 4 hrs use per day)

• Ease of use – single control for battery check, power on & mute

• User-settable threshold alarm

• Battery check

• Built-in sounder with Mute function

• Probe cradle and carry handle

• External DC power & charge socket (charger and batteries not supplied)  

• Rugged all-metal case

• Curly probe lead

• Available with a range of GM, Pancake & Scintillation probes

• Count & Dose rate (cps & uSv/hr) models in stock 

• Instruction Manual (see note below) and Calibration Check Certificate Included

• NEW Optional Rugged And Original Instrument Carry Cases from £39.99 (see below) 

                                            First time buyer?  Please Click HERE

NEWSFLASH! PANCAKE SPECIAL, ALL PRICES REDUCED -- SEE BELOW

SEE BELOW FOR OUR CURRENT STOCK BUT IF YOU WANT TO KEEP YOUR INSTRUMENT SAFE, POP BACK HERE AND CHECK OUT OUR EXCLUSIVE CARRY CASE OPTIONS

Mini Monitor 900s are as tough as old boots but that doesn’t mean you shouldn’t take good care of them. Now you can protect your instrument from the inevitable bumps, knocks and, of course, the weather, with one of our exclusive carry cases.

There are two options: On the right we have a limited number of original (second user) leather-clad rigid boxes, purpose-made specifically for the Mini Monitor 900 series. These cost £39.99.

Alternatively, on the left,  there’s our hugely popular super-tough IP77 rated impact resistant carry case with fitted foam interior, soft grip handle, holes for padlocks and auto pressure release. This case costs £41.99.

Please note the original cases have seen some use but they are complete, in generally good condition and supplied with the original leather shoulder strap.  Shipping is free when purchased with a Mini Monitor 900. Otherwise it is £6.00 to UK addresses and £25.99 elsewhere in the world. OVERSEAS VISITORS: PLEASE CONTACT US TO PURCHASE EITHER OF THESE CASES SO WE CAN ADD SHIPPING COSTS.

To add a case to your order just click chosen case on the drop-down options list.     

Please note that these cases are unsuitable for 900 BPGM EP-15FL & SS300 'frisker' probes due to their size. Larger cases are available on request.

 Important Small(ish) Print. Please Read. It's At The Bottom... 

A SELECTION OF OUR CURRENT STOCK

They're Changing All The Time So Please Ask If The Model That You Require Isn't shown

(actual product shown, more pics available on request)

And by the way, we also buy, repair and calibrate Mini Monitor 900s at very favourable rates. We also have a good selection of spare parts  available, just ask...

900/SL (1152) 
£500.00 inc UK shipping**

Mini Monitor 900/SL 
Tested & Calibrated Prior To Despatch

Typical Applications: General purpose Beta contamination monitor, control
Meter Scale: 0 – 500cps
Probe: Type: CV 49 halogen Beta quenched glass GM tube
Sensitivities: med - hard Beta, Gamma X-Ray
User-Set Threshold Alarm: Yes
Cosmetic Condition: A

900/EL (0192) 
£500.00 inc UK shipping**

Mini Monitor 900/EL 
Tested & Calibrated Prior To Despatch
Typical Applications: Alpha, Beta, general detecting/contamination control
Meter Scale: 0 – 500cps
Probe: Type: DN212, large window  halogen quenched GM tube
Sensitivities: High Sensitivity Alpha, Beta & Gamma
User-Set Threshold Alarm: Yes
Cosmetic Condition: A

900/EP-15 Si-13B8 (1042)*
£480.00 inc UK shipping**

Mini Monitor 900/EP-15 RP
Tested & Calibrated Prior To Despatch
Typical Applications: high sensitivity Beta, Gamma general detecting/contamination control
Meter Scale: 0 – 500cps
Probe: Type: Re-tubed EP15, Si-13B, large window  halogen quenched GM tube
Sensitivities: High Sensitivity Beta & Gamma
User-Set Threshold Alarm: Yes
Cosmetic Condition: A

** NB the probe supplied with this instrument has been fitted with a Si-13b 'pancake' GM tube. It has a 34mm thin mica front window. This is physically more robust than the original LND 7313 tube but with lower alpha sensitivity 

900/EP-15 RP* (9080)

£500.00 inc UK shipping**

Mini Monitor 900/EP-15 RP
Tested & Calibrated Prior To Despatch
Typical Applications: high sensitivity Alpha, Beta, Gamma general detecting/contamination control
Meter Scale: 0 – 500cps
Probe: Type: Re-tubed EP15, Si 8B, large window  halogen quenched GM tube
Sensitivities: High Sensitivity Beta & Gamma
User-Set Threshold Alarm: Yes
Cosmetic Condition: A

* NB the probe supplied with this instrument has been fitted with a Si-8B 'pancake' GM tube. It has a 34mm thin mica front window. This is physically more robust than the original LND 7313 tube but with lower alpha sensitivity 

900/EP-15 SI-13B (1042)
£500.00 inc UK shipping**

Mini Monitor 900/EP-15 RP
Tested & Calibrated Prior To Despatch
Typical Applications: high sensitivity Beta, Gamma general detecting/contamination control
Meter Scale: 0 – 500cps
Probe: Type: Re-tubed EP15, Si-13B, large window  halogen quenched GM tube
Sensitivities: High Sensitivity Beta & Gamma
User-Set Threshold Alarm: Yes
Cosmetic Condition: A

** NB the probe supplied with this instrument has been fitted with a Si-13b 'pancake' GM tube. It has a 55mm thin mica front window. This is physically more robust than the original LND 7313 tube but with lower alpha sensitivity 

900/EP-15 (4131)  NEW LISTING

£550.00 inc. UK Shipping**
Thermo Scientific Mini Monitor 900/EP-15 

Tested & Calibrated Prior To Despatch
Typical Applications: high sensitivity Alpha,Beta, Gamma general detecting/contamination control
Meter Scale: 0 – 500cps
Probe: Type: large window  halogen quenched GM tube
Sensitivities: High Sensitivity Beta & Gamma
User-Set Threshold Alarm: Yes
Cosmetic Condition: A

900/EP-15 (2112)  NEW LISTING

£550.00 inc. UK Shipping**
Mini Monitor 900/EP-15 

Tested & Calibrated Prior To Despatch
Typical Applications: high sensitivity Alpha,Beta, Gamma general detecting/contamination control
Meter Scale: 0 – 500cps
Probe: Type: large window  halogen quenched GM tube
Sensitivities: High Sensitivity Beta & Gamma
User-Set Threshold Alarm: Yes
Cosmetic Condition: A

900/SS300 (1152)

£575.00 inc UK shipping**

Mini Monitor 900/SS300
Tested & Calibrated Prior To Despatch
Typical Applications: monitoring, general detecting
Probe type: Probe: Southern Scientific mica-window 'frisker' Pancake Probe
Sensitivities: Alpha, Beta, Gamma
User-Set Threshold Alarm: Yes
Cosmetic Condition: A

900/E (4032) 
£600.00 inc. UK Shipping**

Mini Monitor 900/E (MFG025)
Tested & Calibrated Prior To Despatch

Typical Applications:  low limit soft beta contamination and monitoring 
Meter Scale 0-1000 cps
Probe: type E thin mica window 6.4cm² area compensated GM tube 

Sensitivities: Alpha, Beta, Gamma, X-Ray
User-Set Threshold Alarm:  Yes
Energy Range: Manuf. specs
Cosmetic Condition: A

900/D 2032 NEW LISTING
£699.00 inc UK shipping**

Thermo Electron Mini Monitor 900/D (MFG025)
Tested & Calibrated Prior To Despatch

Typical Applications:  contamination and monitoring  X-Ray monitoring
Meter Scale 0.5 - 1000 uSv/hr
Probe: type D thin mica end window compensated GM tube 6.0cm² 
Sensitivities: Alpha, Beta, Gamma, X-Ray
User-Set Threshold Alarm:  Yes
Energy Range: Manuf. specs
Cosmetic Condition: A+

900/D 2051 NEW LISTING
£699.00 inc UK shipping**

Thermo Electron Mini Monitor 900/D (MFG025)
Tested & Calibrated Prior To Despatch

Typical Applications:  contamination and monitoring  X-Ray monitoring
Meter Scale 0.5 - 1000 uSv/hr
Probe: type D thin mica end window compensated GM tube 6.0cm² 
Sensitivities: Alpha, Beta, Gamma, X-Ray
User-Set Threshold Alarm:  Yes
Energy Range: Manuf. specs
Cosmetic Condition: A+

SCINTILLATION PROBES

900/CSP (9001)
£580.00 inc UK shipping**

Mini Monitor 900/CSP
Tested & Calibrated Prior To Despatch
Probe type: Custom Nal scintillation probe, TNC connector
Typical Applications: very low level gamma detection,
contamination control
Meter Scale: 0 - 5k cps
Sensitivities: Beta, Gamma & X-Ray
User-Set Threshold Alarm: Yes
Cosmetic Condition: A 

900/2012  5002
£600.00 inc UK shipping**

Mini Monitor 900/CSP
Tested & Calibrated Prior To Despatch
Probe type: Custom Nal scintillation probe, TNC connector
Typical Applications: very low level gamma detection,
contamination control
Meter Scale: 0 - 5k cps
Sensitivities: Beta, Gamma & X-Ray
User-Set Threshold Alarm: Yes
Cosmetic Condition: A 

900/SCI* (8071)
£650.00 inc UK shipping**

Tested & Calibrated Prior To Despatch

Typical Applications: very low gamma detection, contamination control
Meter Scale : 0 – 5k cps
Probe type: Scionix 38 B 57/1.5M-E1, Nal (Ti)  BNC connector  e: 0 – 5k cps
Energy Range: 500keV - 5MeV
Sensitivities: Gamma, X-Ray
User-Set Threshold Alarm: Yes
Cosmetic Condition: A
 

*Note the Scionix 30 B 57 scintillation probe is physically similar to the
Type 44A probe, but with noticeably superior performance, thanks to a
larger Nal (Ti) scintillation crystal and Hammatsu photomultiplier tube. 

900/42B (2060)
£800.00 inc. UK Shipping**

Tested & Calibrated Prior To Despatch
Mini Monitor 900 (MS3088)

Probe type 900/42B Nal (T), PET connector  
Typical Applications: gamma detection, X-Ray contamination control, DVT
Meter Scale: 0 – 5k cps
Energy Range: 5-150keV
Sensitivities: Gamma, X-Ray
User-Set Threshold Alarm: Yes
Cosmetic Condition: A

900/44A (3050) 
£790.00 inc. UK Shipping**

Mini Monitor 900 (MFG 016)
Tested & Calibrated Prior To Despatch

Probe type 900/44A Nal (T), PET connector  
Typical Applications: X-Ray & gamma detection, contamination control
Meter Scale: 0 – 5k cps
Energy Range: 15 - 500keV
Sensitivities: Gamma, X-Ray
User-Set Threshold Alarm: Yes
Cosmetic Condition: A-

900/44A (2090) 
£820.00 inc. UK Shipping**

Mini Monitor 900 (MFG 016)
Tested & Calibrated Prior To Despatch

Probe type 900/44A Nal (T), PET connector  
Typical Applications: X-Ray & gamma detection, contamination control
Meter Scale: 0 – 5k cps
Energy Range: 15 - 500keV
Sensitivities: Gamma, X-Ray
User-Set Threshold Alarm: Yes
Cosmetic Condition: A

900/44A (2080) A+
£880.00 inc. UK Shipping**

Thermo Scientific 900 (MFG 016)
Tested & Calibrated Prior To Despatch

Probe type 900/44A Nal (T), PET connector  
Typical Applications: X-Ray & gamma detection, contamination control
Meter Scale: 0 – 5k cps
Energy Range: 15 - 500keV
Sensitivities: Gamma, X-Ray
User-Set Threshold Alarm: Yes
Cosmetic Condition: A+

900/44A (1072) A++ NOS With Case
£940.00 inc. UK Shipping**

Thermo Scientific 900 (MFG 016)
Tested & Calibrated Prior To Despatch

Probe type 900/44A Nal (T), PET connector  
Typical Applications: X-Ray & gamma detection, contamination control
Meter Scale: 0 – 5k cps
Energy Range: 15 - 500keV
Sensitivities: Gamma, X-Ray
User-Set Threshold Alarm: Yes
Cosmetic Condition: A++ (New Old Stock)

includes fitted waterproof hard carry case

 The All-Important Small Print

The Mini Instruments & Thermo Electron/Scientific/Morgan etc. 900s that we stock were all previously owned but they have generally been very well maintained, regularly calibrated and are in full working order. In addition to any necessary case refurbishments and deep cleaning we carry out a full range of operational checks, including probe supply testing & adjustment, circuit board & cable inspection and pulse-calibration (according to MI protocols and data) of the ratemeter. This is repeated immediately prior to despatch.  Some models have fixed probe/ratemeter cables, others have the factory original PET or TNC type connectors. If you have a specific connector requirement we may be able to help, just ask. All models come with an unconditional  6-months guarantee.

Whenever possible we include a copy of the original user manual; we try to ensure that they are  model-specific but in some cases they may be a generic version, covering operation and maintenance.  We also include a battery holder and in most cases, a vented end-window protective cover. Unless noted otherwise they do not come with any other accessories. Instruments are graded according to cosmetic condition from A+ to C-, with A indicating 'as-new' to very good, and C, full working order but somewhat tatty or with more noticeable scratches, dinks and dents, etc. 

*And finally... Whilst the instruments that we sell are all in full working order, pulse calibrated, and guaranteed, however we do not certify or endorse them for regulatory, health and safety or safety-critical and related applications. See Terms and Condition.

** PLUS, Vital Information For Overseas Buyers:

Hallo, Bonjour, Guten Tag, Ní hao, Namasté, Ahlan bik, Geia!, Shalóm, Hai, Kónnichi wa, Annyeonghaseyo, Szia, Salâm, Witajcie, Privét, Hola, Adaab arz hai, with apologies to anyone we’ve missed…

The prices shown are for UK buyers only, and are inclusive of delivery to mainland UK addresses. Overseas buyers are very welcome but please note that local taxes and customs duties are not included and are the responsibility of the purchaser. Please contact us before ordering for any additional shipping options, which vary according to location. Please also note that this item may be prohibited or restricted in some countries.