Keithley 191
The Keithley 191 is a reliable 5 1/2 digit digital multimeter, offering accurate measurements of voltage, current, and resistance. Ideal for various electronic testing and measurement applications.
- Model
- Keithley 191
- Calibration
- Available on request
- Price
- $185
- Status
- In stock
- RFQ ref
- 191
This unit
The Keithley 191 is a 5½-digit (200,000 counts) manual-ranging digital multimeter engineered for precise DC voltage and resistance measurements across laboratory and field applications. Built on a microprocessor-based architecture, it combines single-slope and charge-balance analog-to-digital conversion with automatic non-linear digital filtering to minimize noise and stabilize display response. The instrument delivers 1 µV DC resolution with 0.005% ±2 digits basic accuracy, and resistance measurement down to 1 mΩ across six ranges extending to 20 MΩ. A pushbutton null function corrects for lead resistance in 2-wire ohms and bucks thermal EMFs in low millivolt measurements.
Technical Specifications Measurement Ranges & Resolution
DC Voltage: 1 µV to 1200 V across 5 ranges; 1 µV resolution; 0.005% ±2 digits accuracy
Resistance: 1 mΩ to 20 MΩ across 6 ranges; 1 mΩ resolution
AC Voltage (Model 1910 option): 10 µV to 1000 V across 4 ranges Display & Conversion Speed
Six 0.5-inch LED digits with decimal point
DC Volts: 1 reading/second; Ohms: 3 readings/second; AC Volts: 2 readings/second
Settling time: <1.3 seconds to 0.005% of final reading for zero to full-scale step input Electrical Characteristics
DC Voltage input impedance: 2 MΩ shunted by 80 dB DC, 50/60 Hz (1 kΩ in either lead)
NMRR: >60 dB at 50/60 Hz
Input LO to power line ground isolation: >1000 MΩ shunted by ~30 pF
Maximum input between LO and power line ground: 1400 V peak, 50/60 Hz
Power consumption: 25 VA maximum
Line power: 105-125 VAC or 210-250 VAC selectable; 50/60 Hz Physical & Environmental
Dimensions: 95 mm H × 235 mm W × 257 mm D
Weight: 2.3 kg
Connectors: 5-way binding posts
Operating temperature: 0°C to 50°C; humidity 0-80% RH to 35°C
Warm-up time: 1 hour to rated accuracy
Key Features
Microprocessor-controlled measurement with automatic non-linear filtering
Null pushbutton with annunciator for zeroing and thermal EMF rejection
Programmable multimeter functionality
High CMRR and NMRR for noise-immune measurements
Typical Applications Precision DC voltage and resistance characterization; thermal EMF compensation in low-level DC measurements; resistance verification across component and circuit-board testing.
Compatibility & Integration Optional Model 1910 AC Voltage module; Model 1901 Plug-in Current Adapter for DC current measurements.
Specifications
| Parameter | Value |
|---|---|
| Frequency Range | 0.002 Hz to 20 MHz | Voltage / Current Range: 1.5 mVp-p to 30 Vp-p (15 Vp-p into 50Ω) |
Keithley 191 — Repair & Calibration Service
Aumictech offers NIST-traceable calibration and repair for the Keithley 191. Calibration covers DC voltage accuracy at all ranges, AC voltage (True RMS) accuracy at 50 Hz, 1 kHz, and 10 kHz, DC current accuracy, resistance accuracy at all decade ranges, frequency accuracy, and diode test voltage. Fluke 87V and 289 also include capacitance and temperature calibration.. All calibrations ship with a NIST-traceable certificate. Turnaround is typically 1–3 business days after receipt.
Common Keithley 191 faults: blown input fuse, worn input jacks, display segment failure, relay contact wear on bench DMMs. Common faults include worn input jacks (banana socket contact wear on the mA and COM terminals), blown input fuses (especially the 440 mA HRC fuse), and display segment failures. Keithley 2000/2001/2002 bench DMMs commonly develop relay contact wear affecting resistance accuracy after extended service.
Keithley 191 price
This Keithley 191 is listed at $185. Calibration is available separately from $450. Contact us for volume pricing or if you need multiple units.
Keithley 191 calibration cost
NIST-traceable calibration for the Keithley 191 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 DC voltage accuracy at all ranges, AC voltage (True RMS) accuracy at 50 Hz, 1 kHz, and 10 kHz, DC current accuracy, resistance accuracy at all decade ranges, frequency accuracy, and diode test voltage. Fluke 87V and 289 also include capacitance and temperature calibration.. Turnaround is 1 to 3 business days after receipt. See full calibration details →
