Keithley 195A
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The Keithley 195A is a 5½-digit LED True-RMS, auto-ranging digital multimeter. It features a standard GPIB interface. Current and True RMS ranges are optional (Opt. 1950).
Key Specifications
| Voltage (DC) | 20 mV to 1000 V full scale in decade ranges; >1 GΩ input resistance (10 MΩ in 20 V and above ranges) |
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| Voltage (AC) | 200 mV to 700 V full scale in decade ranges; 2 MΩ // 75 pF; 250 kHz; True RMS; Crest factor <3:1 |
| Current (DC) | 20 μA to 2 A full scale in decade ranges (Option 1950) |
| Current (AC) | 200 μA to 2 A full scale in decade ranges (Option 1950); True RMS; Crest factor <3:1 |
| Resistance | 20 Ω to 20 MΩ full scale in decade ranges, 2- or 4-terminal |
| Temperature | –200 °C to +630 °C using a PT-100 (DIN 43760) RTD sensor, 4-wire or 3-wire connection |
| Reading rate | 3½ digits: 3.3 ms integration, 76 rdgs/s; 4½ digits: 16.66 ms integration, 36 rdgs/s; 5½ digits: 100 ms integration, 9 rdgs/s |
| Power | 105–125 V or 210–250 V, 50–400 Hz, 24 VA (with low-voltage transformer option, 90–110 V or 180-220 V) |
| Connections | Analog: 5-way binding posts on front and back, switch-selectable; Digital: Trigger Input and Voltmeter Complete output, rear panel, BNC connectors, TTL level; GPIB interface standard |
Links
- Keithley 195A DMM Restore/Calibration/Teardown by Tony Albus @ YouTube
- Keithley 195A @ radiomuseum.org
Internals
If option 1950 is installed, two jumper wires (zero-ohm resistors), W102 and W103, are to be removed from the circuit.
Pictures
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Front panel
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Rear panel
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Internal view, unit with Option 1950 board (bottom left), zero-ohm resistors W102 and W103 are lifted
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Internal view, unit with Option 1950 board (bottom left)
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Internal view, Option 1950 board flipped up
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Internal view of main board under option/shield
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Internal view towards the rear of the unit
