Fluke 845AB High Impedance Voltmeter – Null Detector
The Fluke 845AB is a high impedance voltmeter and null detector, ideal for precision voltage measurements and sensitive circuit testing. It combines accurate voltage readings with null detection capabilities.
- Model
- Fluke 845AB
- Calibration
- Available on request
- Price
- $1,100
- Status
- In stock
- RFQ ref
- 845AB
This unit
The Fluke 845AB is a precision high-impedance DC voltmeter and null detector engineered for sensitive voltage measurements in laboratory, research, and critical circuit testing environments. It combines a wide measurement range of 1 µV to 1000 V DC across 19 ranges with exceptional input impedance to minimize circuit loading and deliver accurate readings. The instrument functions as both a precision voltmeter and null detector with 0.1 µV/V sensitivity, making it ideal for applications requiring detection of small voltage changes or null conditions in bridge circuits and similar setups.
Technical Specifications
- Measurement Range: 1 µV to 1000 V DC, 19 ranges
- Null Detector Sensitivity: 0.1 µV/V
- Accuracy: ±(2% of end scale + 1 µV)
- Input Resistance: 100 MΩ (300 mV range and above); 10 MΩ (100 mV range and below)
- Input Isolation: Better than 10¹² Ω
- DC Common Mode Rejection: Better than 160 dB
- AC Normal Mode Rejection (60 Hz and above): 60 dB above end scale produces less than 2% of end scale error
- AC Common Mode Rejection (below 100 kHz): 120 dB or 100 V rms, whichever is less, produces less than 2% of end scale error
- Maximum Meter Noise: 0.20 µV (1 µV and other ranges); 0.25 µV (3 µV range)
- Response Time to 90% Reading: 1.5 to 5 seconds depending on range
- Zero Stability: Better than 0.15 µV/hour; better than 0.3 µV/day
- Temperature Coefficient of Zero: Less than 0.1 µV/°C (15°C to 35°C); less than 0.2 µV/°C (0°C to 50°C)
- Overload Protection: Up to 1100 V DC on any range
Key Features
- Recorder output: 0–1 V DC, 5 kΩ to 7.5 kΩ source impedance, 0.5% linearity
- Configurable as DC amplifier with maximum gain of 120 dB
- Zero control range: ±5 µV minimum
- Dual-power operation: 115/230 VAC ±10%, 50 to 440 Hz, or rechargeable battery
- Battery runtime: Approximately 40 hours per full charge
- Full recharge time: 16 hours
- Power consumption during recharge: Approximately 6 watts
- Trickle-charge capability during line operation
Typical Applications
- Bridge balance and null detection
- Thermoelectric measurements
- Potentiometric circuits
- High-impedance sensor readout
- Standards calibration and verification
- Research applications requiring sub-microvolt sensitivity
Specifications
| Parameter | Value |
|---|---|
| Voltage / Current Range | 1 µV to 1000 V DC |
Fluke 845AB — Repair & Calibration Service
Aumictech offers NIST-traceable calibration and repair for the Fluke 845AB. Calibration covers calibration scope varies by instrument type: vacuum gauges are verified at multiple pressure points against NIST-traceable pressure standards; spectrophotometers at wavelength accuracy and photometric accuracy points; strain gauge indicators at bridge excitation accuracy and full-scale output accuracy; pH meters against certified buffer solutions at pH 4, 7, and 10.. All calibrations ship with a NIST-traceable certificate. Turnaround is typically 1–3 business days after receipt.
Common Fluke 845AB faults: vacuum gauge filament failure (ionization gauges), spectrophotometer D2 lamp end-of-life, wavelength motor failure, strain indicator front-panel binding post corrosion, pH electrode conditioning failure. Most specialty laboratory instruments fail at their electromechanical interfaces first — vacuum gauge connectors and filament assemblies, spectrophotometer lamp housings and motor drives, strain indicator binding post corrosion. Component-level repair is standard; manufacturer support for legacy instruments is often limited, making third-party bench repair the practical path.
Fluke 845AB price
This Fluke 845AB is listed at $1,100. Calibration is available separately from $450. Contact us for volume pricing or if you need multiple units.
Fluke 845AB calibration cost
NIST-traceable calibration for the Fluke 845AB is $450 (standard — pass/fail certificate and calibration sticker) or $650 (full measured data at every test point, reference standards documented, traceability chain included). Calibration for this instrument covers calibration scope varies by instrument type: vacuum gauges are verified at multiple pressure points against NIST-traceable pressure standards; spectrophotometers at wavelength accuracy and photometric accuracy points; strain gauge indicators at bridge excitation accuracy and full-scale output accuracy; pH meters against certified buffer solutions at pH 4, 7, and 10.. Turnaround is 1 to 3 business days after receipt. See full calibration details →
