Keithley 7158 Low Current Scanner Card

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.