The Keithley 197A is a 5½-digit autoranging microvolt DMM delivering precision measurements across voltage, current, resistance, and specialized functions. With ±220,000-count resolution and sensitivities to 1µV, 1nA, and 1mΩ, it addresses demanding benchtop and field applications requiring high accuracy and stability. The backlit LCD display indicates polarity, function, range, and status, while autoranging capability (300ms average per range) and manual mode options provide measurement flexibility across nine distinct functions.
## Technical Specifications
**Display & Resolution**
• ±220,000-count backlit LCD, 0.45 inches high
• Resolution: 1µV to 10mV (voltage); 1nA to 100µA (current); 1mΩ to 10kΩ (resistance)
**Voltage Measurement**
• DC ranges: 200mV to 1000V; AC ranges: 200mV to 750V
• DC accuracy: 0.011% ±2 counts (2V range, 1 year)
• AC accuracy (True RMS, 50Hz–10kHz): 0.35% + 100 counts; 5% + 400 counts (50kHz–100kHz, higher ranges)
• Input resistance: >1 GΩ (200mV, 2V ranges); 11MΩ to 10MΩ (higher ranges)
• Maximum input: 1000V DC or peak AC
• 3dB bandwidth (AC): 300kHz typical
**Current Measurement**
• Ranges: 1nA to 10A
• DC/AC accuracy: 0.2% + 15 counts (200µA–200mA); 0.5% + 15 counts (10A)
• Overload protection: 2A fuse (250V), externally accessible
**Resistance Measurement**
• Ranges: 1mΩ to 220MΩ
• Automatic 2- or 4-terminal configuration
• Accuracy: 0.01% + 2 counts (200Ω range); 2.00% + 1 count (200MΩ range, 1 year, 22°–24°C)
• Test current: 2mA nominal; open circuit voltage: +5V
**Additional Functions**
• True RMS AC measurement to 100kHz
• Diode test (junction voltage to 2.2V; 1.6mA test current)
• dB mode with selectable impedance: 50, 75, 93, 135, 300, 600 ohms
• Data logging: 100-point storage, rates from 3/second to 1/hour
• Min/Max detection and storage
• Relative mode with pushbutton zeroing
**Environmental**
• Operating: 0° to 50°C; <80% RH (≤35°C); linearly derated 3%/°C (35°–50°C)
• Storage: -40° to +70°C
• Warm-up: 1 hour to rated accuracy
## Key Features
• Autoranging (DC volts, AC volts, ohms) or manual mode
• Exceptional low-voltage sensitivity: 1µV resolution
• Nanoampere-level current measurement capability
• Selectable data logging with continuous min/max tracking
• High input impedance minimizes loading errors
• Portable design with optional battery pack for field deployment
## Typical Applications
• Precision DC and AC measurement in R&D and manufacturing
• Sensor and transducer characterization
• Low-level signal detection in electronic circuits
• Temperature coefficient and drift analysis
• Resistance measurement from milliohm to megohm scales
• Diode junction voltage verification
## Compatibility & Integration
Manual and autoranging modes support diverse measurement workflows. Relative mode enables differential testing against reference baselines. The 100-point logger accommodates process monitoring and trend analysis without external data acquisition hardware.
