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F250 PRT Bench Dual Channel Thermometer.

F250 PRT High Accuracy Thermometer.
F250 Bench Thermometer provides high accuracy, dual channel temperature measurement with Platinum
Resistance Thermometers - PRT's - and uses AC bridge technology as developed by ASL for Standards
Laboratories throughout the world. Model F250 Digital Bench Thermometer requires no regular recalibration,
the AC circuit techniques eliminating thermal emf's and drift, while providing excellent long term stability.

F250 PRT Bench Thermometer.

Model  Description 
F250  F250 Precision Thermometer. High Accuracy, Dual Channel

The 8 or 16 channel SB250 switchbox, or scanner, complements the F250 Thermometer in appearance and
Adding no extra system errors you can use one or two scanners, one each on Inputs A and B, with manual
switching from the keypad or under interface control. You can choose to connect your probes to front or back
panels on both F250 and the scanners.
Configuration examples are; A single scanner attached to Input A, lets you read up to 8 or 16 thermometers
directly, or measure them differentially to a probe on Input B. Similarly with two scanners, you can read up to
32 probes directly, or 16 differential pairs. SB250 scanners turn the F250 into a powerful logging system,
particularly when used with ASL's LabWindows software

F250 PRT High Accuracy Thermometer Specification
Range  -200°C to +962°C, depending on PRT used. 
Accuracy  F250 only: ±0.005°C (±5mK) at 0°C, otherwise <±0.01°C (±10mK)
F250 + T100-250: ±.25mK (-50°C to +250°C)
F250 + T100-450: -70°C (±45mK), -40°C to +250°C (±25mK),
+250°C to +450°C (±100mK)
F250 + T100-650: -189°C to 420°C (±20mK), +420°C to +550°C (±35mK)

Resolution  Low resolution: 0.01°C , 0.01°F, 0.01K, 0.01ohms (display) or
0.001ohms (via interface).
High resolution: 0.001°C, 0.001°F, 0.001K, 0.001ohms (display) or
0.0001ohms (via interface). 

Repeatability  ±2 least significant digits (±0.002°C), included in accuracy 
Stability  Long term: typically <0.002ohms per year (<0.005°C for Pt100). 
Temperature co-efficient  <±0.0005°C/°C ambient change.
Operating ambient: 15°C to 25°C for best accuracy.
0°C to 50°C maximum, non-condensing. 

Data entry format  ITS90 coefficients, Calendar van Dusan coefficients,
Calendar van Dusan data pairs or EN60751 for un-calibrated probes. 

Probe Current  1 mA constant current source. 
Probe Types  Pt100 to EN60751 with nominal R0=100 and "Alpha"=0.00385,
plus10 and 25ohm high alpha probes up to 0.00392. 

Thermometer input connectors  Front panel:5 pin industrial DIN socket
Rear panel:5 pin screw terminal plug. 

Optional Communications  RS232C: Baud rates 4800, 9600 and 19200. Parity, data and stop bits
user selectable. IEEE-488: Address selectable from 1 to 7.
Analogue output: ±10V DC full scale output, resolution 1mK or 10mK
depending on front panel resolution setting. Linearity ±0.05% full scale.