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  • Fluke Calibration 1502A-256 Thermometer Readout

Fluke Calibration 1502A-256 Thermometer Readout


Availability: Normally in Stock / Short Lead Time

The 1502A Tweener features accuracy up to ±0.006 °C (the 1504 is even more accurate, up to ±0.002 °C).

The 1502A Tweener features accuracy up to ±0.006 °C (the 1504 is even more accurate, up to ±0.002 °C). In addition, it reads 100-ohm, 25-ohm, and 10-ohm probes, has a resolution of 0.001 °C across its entire range, and is the smallest unit in its class. It also has an optional battery pack for completely portable operation.

Each Tweener is programmable to match a probe’s constants for maximum linearity and accuracy. All probe constants and coefficients are programmed through simple, front-panel keystrokes. Temperature is displayed in °C, °F, K, or resistance in ohms.

The 1502A accurately measures the resistance of the probe and then converts the resistance to a temperature value using its built-in algorithms.

For convenience, the 1502A reads the common industrial grade IEC-751 or “385” ALPHA RTD without any programming. Enter the actual R0 and ALPHA of the individual probe for increased accuracy. For maximum accuracy, use the ITS-90 formulas. The Tweener accepts the subranges 4 and 6 through 11.

ITS-90 formulas reside in the Tweener’s firmware. If your probe has been calibrated for any of the above subranges of the ITS-90, you simply enter the coefficients directly into your Tweener.

Each thermometer comes complete with an RS-232 interface for automation of temperature data collection, calibrations, or process control functions. An IEEE-488 interface is available as an option.

The 1502A is calibrated digitally using the front-panel buttons. You never have to open the box to calibrate it. This calibration protocol further reduces the cost of the 1502A. It goes where you go and works the way you want it to.

1502A/1504 - Best performance thermometers in their price range

  • Two Tweeners to choose from—reading PRTs or thermistors
  • Battery packs available
  • Best price/performance package

One of Hart’s best-selling products is the Tweener thermometer, and there’s a reason. No other company, not one, has a reference thermometer that comes close to the performance and features of the Tweener for anywhere near its price.


With our 9934 LogWare, both Tweener models may be used for real-time data acquisition. Collect data and analyze it graphically or statistically. Additionally, Tweeners may be used as reference thermometers with our MET/TEMP II software.

Battery pack

Want to take your Tweener on the road? Order Hart’s 9320A Battery Pack. Our battery gives you 36 hours between charges, allowing you to take your work wherever you need.

Calibration choices

Each Tweener and its accompanying probe (sold separately) have their own individual calibration reports. Overall system error can be calculated from the individual errors, rendering the added cost of system data unnecessary. However, for those requiring it, system data is available at two or more temperatures of your choice. (See Calibration Model 1929-X )


1502A 1504
Temperature Range −200 °C to 962 °C (−328 °F to 1764 °F) Any thermistor range
Resistance Range 0W to 400W, auto-ranging 0W to 1 MW, auto-ranging
Probe Nominal RTPW: 10W to 100W
Characterizations ITS-90 subranges 4, 6, 7, 8, 9, 10, and 11
IPTS-68: R0, a, d, a4, and c4
Callendar-Van Dusen: R0, a, d, and b
Steinhart-Hart thermistor polynomial
Callendar-Van Dusen: R0, a, d, and b
Resistance Accuracy
(ppm of reading)
0W to 20W: 0.0005W
20W to 400W: 25 ppm
0W to 5 KW: 0.5W
5 KW to 200 KW: 100 ppm
200 KW to 1 MW: 300 ppm
Temperature Accuracy ±0.004 °C at −100 °C
±0.006 °C at 0 °C
±0.009 °C at 100 °C
±0.012 °C at 200 °C
±0.018 °C at 400 °C
±0.024 °C at 600 °C
±0.002 °C at 0 °C
±0.002 °C at 25 °C
±0.004 °C at 50 °C
±0.010 °C at 75 °C
±0.020 °C at 100 °C
(Using 10 KW thermistor sensor, a=0.04. Does not include probe uncertainty or characterization errors.)
Operating Temperature Range 16 °C to 30 °C 13 °C to 33 °C
Resistance Resolution 0W to 20W: 0.0001W
20W to 400W: 0.001W
0W to 10 KW: 0.01W
10 KW to 100 KW: 0.1W
100 KW to 1 MW: 1W
Temperature Resolution 0.001 °C 0.0001 °C
Excitation Current 0.5 and 1 mA, user selectable, 2 Hz 2 and 10 mA, automatically selected
Measurement Period 1 second
Digital Filter Exponential, 0 to 60 seconds time constant (user selectable)
Probe Connection 4-wire with shield, 5-pin DIN connector
Communications RS-232 serial standard
IEEE-488 (GPIB) optional
Display 8-digit, 7-segment, yellow-green LED; 0.5-inch-high characters
Power 115 VAC (±10 %), 50/60 Hz, 1 A, nominal
230 VAC (±10 %), 50/60 Hz, 1 A, nominal, specify
Size (HxWxD) 61 x 143 x 181mm (2.4 x 5.6 x 7.1 in)
Weight 1.0 kg (2.2 lb.)
Probes from Hart 5615, 5627, 5626, 5628, 5622 5640-44, 5610-65
Calibration ISO 17025-accredited calibration provided
Temperature ranges and accuracy may be limited by the sensor you use.