Keithley 177

The Keithley 177 Microvolt DMM is a 4½-digit digital multimeter marketed as a "Microvolt DMM" because it has 1 μV display resolution in the 20 mV range.

Manuals – Specifications – Links – Pictures

It was also available re-branded by Racal-Dana as the model 4003.

Key Specifications

Voltage	20 mV (AC: 200 mV) to 1000 V in decade ranges
Current	20 μA (AC: 200 μA) to 2 A in decade ranges
Resistance	20 Ω to 20 MΩ in decade ranges
Power	105–125 or 210-250 V, 50–60 Hz, 8 W
Features	AC True RMS
Options	Option 1788 – Battery pack (6 h runtime) Option 1793 – BCD output (isolated) Option 1793 – GPIB (isolated)

Links

• Keithley 177 @ radiomuseum.org
• Keithley 177 @ amplifier.cd (German/English text)
• Keithley 177 Microvolt DMM Repair – EEVblog #777 @ YouTube
• Refurbishing a Keithley 177 Microvolt DMM – Craig Hollinger @ YouTube
• Power Supply Replacement for Keithley 177 (to replace failed transformer) / PCB project @ Tindie
• See also Keithley 197

Pictures

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  Re-drawn schematics

please add

Components

Some Parts Used in the Keithley 177

Part	Part Number(s)	Class	Description	Used in
AD536	156-1259-00	Monolithic integrated circuit	RMS/DC converter	DM501A • DM502A • DM5010 • Keithley 177 • Keithley 179 • Keithley 195A
Intersil ICL8052		Monolithic integrated circuit	4½ digit A/D converter	Keithley 177 • Keithley 179 • Keithley 480