The Keithley 7057A is a 9-channel thermocouple scanner card engineered for integration into Keithley scanner mainframes. It delivers automated, high-precision temperature measurements by multiplexing signals from multiple thermocouple sources while maintaining sub-microvolt contact potential and integrated cold junction compensation. The card combines thermocouple scanning with an onboard temperature reference function, eliminating the need for external compensation and enabling accurate thermal profiling across distributed measurement points.
## Technical Specifications
**Channels & Switching**
• 9 thermocouple channels plus 1 temperature reference channel
• 2-pole Form A relay configuration with common guard
• Contact potential: less than 1 µV per channel ( 10⁸ closures cold switching; > 10⁶ closures at maximum signal levels
• Relay drive current: 12 mA typical
**Signal Handling**
• Signal level: up to 35 V peak; up to 100 mA peak (resistive load only); 2 VA maximum (non-inductive load only)
• Channel isolation: > 10⁸ Ω, 10 pF
• Input isolation: > 10⁷ Ω, 150 pF
• Common mode voltage: 200 V peak
**Temperature Reference**
• Type: Linearized thermistor bridge
• Output: −1 mV/°C (0 mV at +30°C)
• Accuracy (1 year): ±0.25°C (10°C to 35°C); ±0.5°C (0°C to 10°C and 35°C to 50°C)
• Temperature offset: ±0.05°C maximum within isothermal block; ±0.1°C maximum between any two terminals
• Dynamic offset: ±0.1°C maximum after one hour settling following 10°C environmental step change
• Warm-up time: 1 hour to rated accuracy
**Physical & Connectivity**
• Dimensions: 32 mm H × 114 mm W × 272 mm L
• Weight: 0.54 kg
• Connections: Screw terminals (#4) on isothermal block; accepts #18 AWG wire maximum
• Operating environment: 10°C to 35°C
## Key Features
• Unified thermocouple scanning and temperature reference on a single card
• Sub-microvolt contact potential eliminates measurement drift
• Isothermal block design minimizes inter-channel temperature gradients
• Low relay drive current reduces mainframe power demands
• High channel isolation enables multi-point monitoring in electrically noisy environments
## Typical Applications
• Thermal profiling across semiconductor processes and manufacturing equipment
• Environmental and chamber monitoring with distributed sensor networks
• Process control requiring simultaneous multi-point temperature feedback
• Equipment validation and thermal characterization studies
## Compatibility & Integration
The 7057A installs directly into Keithley scanner mainframes via rear-panel connectivity. Its compact form factor and standardized screw terminal interface facilitate integration into existing multi-channel measurement systems without external reference hardware.
