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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

MicroK Precision Thermometry Bridge

Thermometry Bridge for Thermocouples, SPRTs and Thermistors

The MicroK 70 and 125 models are designed for the Primary Temperature Laboratories while the MicroK 250 and 500 models were designed for the Secondary Laboratory as well as a wide range of high accuracy industrial and scientific calibration applications. The instruments use a completely new measurement technique to achieve accuracies better than 0.02 parts per million (ppm).

When used with a 0°C cold junction reference unit, or by measuring the junction temperature with a PRT on another channel the instrument is capable of low uncertainty precision thermocouple measurements, with a voltage uncertainty of just 0.25μV, equivalent to 0.01°C with a Platinum / Gold Thermocouple at 1000°C.

The microK range consists of four instruments offering a choice of measurement accuracy of 0.07 to 0.5ppm over the whole range, equivalent to 0.07mK to 0.5mK over the whole range of an SPRT with an Ro >2.5Ω. Better at unity ratio.

The instruments in the microK range offer performance characteristics and features which are simply not available elsewhere. Comparable instruments available internationally do not achieve the same accuracy or stability (zero drift characteristics with SPRT measurements are not obtainable in any other instrument), other instruments do not support the same variety of sensors, and offer considerably less operational features. The microK family uses solid state construction with no potentiometers or relays which ensures long term reliability and low cost of ownership, a feature of growing international importance.

In April 2017 Isotech won a Queen’s Award for Enterprise in the Innovation category for the co-development of the microK, read more in our news section.

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


MicroK Datasheet 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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