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MicroK Precision Thermometer
Isotech, MicroK Thermometry Bridge
3 Channel Primary Standard Thermometer for SPRTS, Thermocouples, & Thermistors
  • Accuracy: 0.07 ppm (±0.017mK at 0ºC) to 0.5 ppm in 4 different models
  • Resolution: 0.000001ºC. (0.001mK)
  • Zero Drift for resistance ratio measurements and only 3ppm/year on voltage
  • Keep-warm currents for SPRTs
  • 0 to 10mA sense currents
  • Touch Screen, USB mouse, Keyboard and USB drive as standard - Simple Operation
  • <2 second measurement time

Product Code: MICROK

   Product Description

Precision Thermocouple Bridge MicroK

Thermometry Bridge for Thermocouples, SPRTs and Thermistors

The New MicroK Precision Thermometer Offers Unrivalled Accuracy, Stability & Versatility The microK family of precision thermometry bridges use a completely new measurement technique to achieve accuracies to better than 0.02ppm.

With four models to suit all levels of temperature metrology from National Measurement Institutes to those wanting a solution to make low uncertainty temperature measurements in a range of applications.

In addition to making the best resistance measurements the microK makes high accuracy thermocouple measurements with a voltage uncertainty of <0.25ìV. The microK can be used with all standard thermometer types including SPRTs, Standard Thermocouples, Industrial PRTS and thermistors.

First introduced in 2006 the microK has proven use at the world’s leading NMIs and many commercial laboratories. After years of experience and success we now introduce new models with even better performance and new features. All microK models now include IEEE-488 General Purpose Interface Bus as well as RS232 and USB. The microK 70 and microK 125 also feature an Ethernet port and can be monitored and controlled across a LAN.

The MicroK continues to receive international attention as another Isotech development that allowd temperature metrologists world wide to achieve better measurements easier!

Key Features Performance by Design MicrosKanner
What are the advantages
of the microK over

conventional ratio


Can work with thermocouples

as well as resistance thermometers

Simple Touch Screen operation with easy to use interface and data logging options

Can connect USB Memory Stick, Keyboard, Mouse

Built in database for all your thermometers and reference resistors

The microK does not use tapped transformers restricting its measurement range

Wide range of resistance, 0 - 500 kΩ

No Moving Parts

Displays Temperature, Resistance and Ratio

Statistical Mode & Chart Display

Plug and Play Channel Expanders, control up to 92 channels from the touch screen

No PC needed, the display can show temperature and resistance in addition to ratio

“Performance by Design” was the
mantra and passion behind the

development of the microK. On Day

1 a decision was made, “ no tweak

pots” (such as used on AC Bridges

to correct for flux leakage), no

software adjustment, no “self calibration”

but performance by design.

The microK achieves its resistance

ratio accuracy by design, not

adjustment and is uniquely drift free.

To be clear, as a ratio bridge the

microK is drift free. This is a benefit

of the substitution topology used and

provides one of the microK’s most

exciting features, it is inherently drift

The microK realizes its superior
linearity and low noise through a

number of novel approaches,

including a new noise reduction

technique, new solid state switching,

new guarding arrangements and a

sophisticated substitution topology

to achieve zero drift.

So perhaps it will be of no surprise

to learn it also uses a new type of

ADC, the concept for the core ADC

technology was licensed from NPL

(the UK’s national standards

laboratory) and operates under

NPL’s “Technology Applied”


The MicrosKanner replicates the input

system of the microK for all 10 of its

input channels. Measurements made

with a microsKanner are therefore to

the same uncertainty as the microK

itself. A microK system can be

expanded to a maximum of 92

channels without losing

measurement performance.

The use of plug-and-play technology

means that the extra channels appear

automatically on the microK when you

connect it to a microsKanner.

Parameter microK 70 microK 125 microK 250 microK 500
Accuracy Whole Range
(SPRT Ro ≥2.5Ω)[1]
0.07ppm 0.125ppm 0.25ppm 0.5ppm
Accuracy Ratio 0.95 to 1.05 0.017ppm 0.03ppm 0.06ppm 0.125ppm
Equivalent Temperature Accuracy [2] 0.017mK 0.03mK 0.06mK 0.125mK
Resolution 0.001 mK 0.001 mK 0.01 mK 0.01 mK
Resolution Voltage 10nV 10nV 10nV 10nV
Stability 0ppm/yr [3] 0ppm/yr [3] 0ppm/yr [3] 0ppm/yr [3]
TC (resistance ratio) [4] 0ppm/°C [3] 0ppm/°C [3] 0ppm/°C [3] 0ppm/°C [3]
Resistance Range 0 - 100 kΩ 0 - 100 kΩ 0 - 500 kΩ 0 - 500 kΩ
Voltage Range (Thermocouple) ± 125 mV ± 125 mV ± 125 mV ± 125 mV
Internal Resistance Standards 25, 100, 400Ω 25, 100, 400Ω 1, 10, 25, 100, 400Ω 1, 10, 25, 100, 400Ω
Internal Standard TCR <0.05ppm/°C TCR <0.05ppm/°C 1, 10Ω <0.6ppm/°C < 5ppm/year 1, 10Ω <0.6ppm/°C < 5ppm/year
Resistor Stability Annual Stability <2ppm/year Annual Stability <2ppm/year 25, 100, 400 <0.3ppm/°C <5ppm/year 25, 100, 400 <0.3ppm/°C <5ppm/year
Interfaces RS232, GPIB & USB & Ethernet RS232, GPIB & USB & Ethernet RS232, GPIB & USB RS232, GPIB & USB
Power 25W maximum, 1.5A (RMS) maximum 25W maximum, 1.5A (RMS) maximum 20W maximum, 1.5A (RMS) maximum 20W maximum, 1.5A (RMS) maximum
Weight 13.3kg 13.3kg 12.4kg 12.4kg

1. Over whole range of SPRT, -200°C to 962°C. For Ro=2.5Ω increased by a factor of 2.5
2. E.g.: 25Ω SPRT with a 25Ω standard restor at water triple point or with direct comparison of similar SPRTs.
3. The microK uses a "substitution technique" in which the Device-Under-Test and the Reference are successively switched into the same position in the measuring circuit. This means that the stability of resistance ratio measurements is immeasurably small.
4. Using external reference resistors

Two Minute microK Tour

A short video illustrating the main features of the microK precision thermometry bridge.

Thermocouple Measurement

Using the microK to measure a thermocouple

Adding a Standard Resistor

How to add a new Standard Resistor to the microK

Adding an SPRT

How to add a new SPRT to the microK

Ratio Measurement

Using the microK to make a ratio measurement


micro KDatasheet microskanner Datasheet microK Manual microK Manual microK Manual
MicroK Datasheet Microskanner Datasheet MicroK 70/125 Manual MicroK 250/500 Manual Microskanner Manual
microK Manual microK Manual microK Manual microK Manual microK Datasheet
Cal Lab Article MicroK Buyer's Guide MicroK FAQ MicroK-400 NIST Certificate Español

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MilliK Precision Thermometer RBC - Resistance Bridge Calibrator MicrosKanner SPRT (Standard Platinum Resistance Thermometer), Model 670
Base Price: $4,985.00

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