The Keithley 7158 Low Current Scanner Card is a 10-channel switching module for automating low-current measurements in multi-signal test applications. It installs directly into Keithley Models 705 and 706 mainframes and uses single-pole, single-throw normally open relays to route any one of ten input signals to a common output, or one input signal to any of ten outputs. The card’s exceptional offset current error—specified below 1 pA with typical performance of 30 fA—makes it ideal for measuring leakage currents and insulation resistance where measurement noise must be minimized.
## Technical Specifications
• **Channels:** 10 per card
• **Relay Type:** SPST normally open; one isolation relay per card
• **Offset Current Error:** <1 pA (typical <30 fA)
• **Signal Range:** AC or DC, 0 to 100 mA, 0 to 30 V peak (resistive load)
• **Contact Resistance:** <1 Ω
• **Contact Potential:** 10⁶ closures at maximum signal; >10⁷ closures at low signal
• **Bandwidth (–3 dB):** Typically 1 MHz
• **Actuation Time:** 10¹⁴ Ω
• **Input Isolation (Differential):** >10⁹ Ω, 10⁹ Ω, <150 pF
• **Common Mode Voltage:** Maximum 30 V
• **Relay Drive Current:** 100 mA typical per card
## Key Features
• BNC connectors for input and output with integrated shielding for low-noise operation
• Daisy-chainable design via dual output connectors for expanded channel configurations
• Isolation relay minimizes cross-card interference and disconnects all circuitry when no channel is active
• Signal LO (analog ground) common to all channels and output
## Typical Applications
• Insulation resistance measurements
• Reverse leakage tests on semiconductor junctions
• Gate leakage tests on field-effect transistors
## Compatibility & Integration
Field-installable in Keithley Models 705 and 706 scanner mainframes. Operating temperature range: 0° to 40° C (35° C maximum at 70% RH). Storage range: –25° to 60° C.
