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Model 425 Specifications

(Specifications do not include probe error, unless otherwise specified)

General measurement

Input type: Single Hall effect sensor

Maximum update rate: 30 rdg/s

Probe features: Linearity compensation, probe zero, and hot swap

Measurement features: Autorange, max hold, relative mode, and filter

Probe connector: 15-pin D-sub socket

DC measurement

Probe type ranges Filter on 4¾-digit resolutionFilter off 3¾-digit resolution
HST probe
350 kG 000.01 kG000.1 kG
35 kG00.001 kG00.01 kG
3.5 kG0.0001 kG0.001 kG
350 G000.02 G000.1 G
HSE probe
35 kG00.001 kG00.01 kG
3.5 kG0.0001 kG0.001 kG
350 G000.01 G000.1 G
35 G00.001 G00.01 G
UHS probe (discontinued)
35 G00.001 G00.01 G
3.5 G0.0001 G0.001 G
350 mG000.02 mG000.1 mG

Measurement resolution (RMS noise floor): Indicated by value in above table for shorted input

Display resolution: Indicated by number of digits in above table

DC accuracy: ±0.20% of reading ±0.05% of range

DC temperature coefficient: -0.01% of reading -0.003% of range/°C

DC filter: 16-point moving average

AC measurement

Probe type ranges 3¾-digit resolution
HST probe
350 kG 000.1 kG
35 kG00.01 kG
3.5 kG0.001 kG
350 G000.1 G
HSE probe
35 kG00.01 kG
3.5 kG0.001 kG
350 G000.1 G
35 G00.01 G
UHS probe (discontinued)
35 G00.01 G
3.5 G0.001 G
350 mG000.1 mG

Measurement resolution (RMS noise floor): Indicated by value in above table, measured at mid-scale range

Display resolution: Indicated by number of digits in above table

 Narrow band modeWide band mode
AC accuracy±2% of reading, ±0.05% of range (20 Hz to 100 Hz); ±2.5% of reading, ±0.05% of range (10 Hz to 400 Hz)±2% of reading, ±0.05% of range (50 Hz to 10 kHz)
AC frequency response10 Hz to 400 Hz50 Hz to 10 kHz
Minimum input signal>1% of range>1% of range, except >2% of range on lowest range

AC specifications based on sine wave inputs or signals with crest factors <4.

AC temperature coefficient: ±0.01% of reading ±0.006% of range/°C

Front panel

Display type: 2-line × 20-character LCD display module with 5.5 mm high characters and LED backlight

Display units: gauss (G), tesla (T), oersted (Oe), and ampere per meter (A/m)

Display update rate: 3 rdg/s

Display resolution: To ±4¾ digits

Units multipliers: µ, m, k, M

Display annunciators : DC, RMS, max, alarm

Keypad: 14-key membrane

Front panel features: Display contrast control and keypad lock-out



Function: Emulates a standard RS-232 serial port

Baud rate: 57,600

Connector: B-type USB connector

Reading rate: To 30 rdg/s

Software support: LabVIEW™ driver


Settings: High setpoint, low setpoint, inside or outside, algebraic or magnitude, audible on/off, and sort

Actuators: Display annunciator, sort message, beeper, and relay


Number: 1

Contacts: Normally open (NO), normally closed (NC), and common (C)

Contact rating: 30 VDC at 2 A

Operation: Follows alarm or operated manually

Connector: Shared 25-pin D-sub socket

Monitor output

Configuration: Real time analog voltage output proportional to measured field

Range: ±3.5 V

Scale: ±3.5 V = ±full scale on selected range

Frequency response: DC to 10 kHz

Accuracy: Offset and single point gain corrected to ±0.5% of reading ±0.1% of range, linearity is probe dependent

Minimum load resistance: 1 kΩ (short circuit protected)

Connector: Shared 25-pin D-sub socket


The Model 425 is the replacement for the Model 421 with a new software command set.

Ambient temperature: 15 to 35 °C at rated accuracy, 5 to 40 °C with reduced accuracy

Ambient field: Up to 100 G DC, measured at the instrument chassis

Power requirement: 100 to 240 VAC, 50 to 60 Hz, 40 VA

Size: 216 mm W × 89 mm H × 318 mm D (8.5 in × 3.5 in × 12.5 in), half rack

Weight: 2.1 kg (4.6 lb)

Approval: CE mark, RoHS

Probes and extensions

Probe compatibility: Full line of standard and custom probes (compatible with Model 425/455/475 probes)

Hall sensor compatibility: Front panel programmable sensitivity and serial number for user supplied Hall sensor using HMCBL cable

Extension cable compatibility: Probe extension cables with an EEPROM are available from 10 ft to 100 ft