Keithley 7057A

The Keithley 7057A is a 9-channel thermocouple scanner card designed for integration into Keithley scanner mainframes. This card combines switching functionality with an onboard temperature reference, enabling simultaneous measurement of multiple thermocouple signals and conversion to temperature readings. The card delivers ultra-low contact potential (< 1µV per channel, equivalent to 10⁸Ω, < 10pF nominal) for precision cold-junction compensation and transducer monitoring.

– Technical Specifications

• Channels: 9 plus integrated temperature reference
• Contact Configuration: 2-pole Form A with common guard
• Signal Capability: Up to 35V peak, 100mA peak; maximum 42V, 100mA, 2VA (resistive load)
• Contact Potential: 10⁸ closures (cold switching); > 10⁶ closures at maximum signal levels
• Contact Resistance: < 1.4Ω nominal; < 2Ω at end of life
• Actuation Time: 10⁸Ω, 10⁹Ω)
• Input Isolation: > 10⁷Ω, 10¹⁰Ω)
• Offset Current: < 10⁻¹²A (typical < 10⁻¹³A)
• Common Mode Voltage: 200V peak
• Temperature Reference: Linearized thermistor bridge; −1mV/°C (0mV @ +30°C)
• Reference Accuracy (1 year): ±0.25°C (10°C to 35°C); ±0.5°C (0°C to 50°C extremes)
• Temperature Offset: ±0.05°C max (HI to LO within channel); ±0.1°C max (between isothermal block terminals); ±0.1°C additional after 10°C step (1 hour settling)
• Warm-Up Time: 1 hour to rated accuracy
• Connector Type: Screw terminals in isothermal block (#18 AWG max); #4 rear-panel terminals on mainframe
• Dimensions: 32mm H × 114mm W × 272mm L
• Weight: 0.54kg

– Key Features

• Guarded signal paths connected to heat sink minimize crosstalk and thermal drift
• Isothermal block design ensures temperature uniformity across all channels
• Bridge power derived from non-isolated internal supply with external isolated supply provision
• Cold-switching rated contact life exceeds 100 million closures

– Compatibility & Integration

The 7057A is compatible with Keithley 7001 and 7002 scanner mainframes, delivering integrated thermocouple acquisition and reference compensation without external hardware.