Keithley 175A

The Keithley Model 175A is a bench/portable DMM with 0.03% basic DCV accuracy. It has a 4 1/2 - digit LCD display with a switch selectable electroluminescent backlight.

The 175A offers extended measurement capabilities including a 10A current range, 100kHz bandwidth, and resistance measurements from 10mΩto 200MΩ. Annunciators provide function, range, and feature indication.

With the Model 175A, choose either manual or autoranging. Fast autoranging is available on DC volts, ohms, AC volts, and dB.

The Model 175A’s 100-point data logger is capable of storing data at six selectable rates from three readings per second to one every hour. Data can be recalled from the front panel. This feature enables collection of response curve data and monitoring of drifts or rates of change without the need for a printer.

The Min/Max hold feature holds both lowest and highest readings over a selected period of time.

The dB function makes the Model 175A suitable for audio and communications applications. Direct dB readings are given throughout a dynamic range from –98 to +62dB, with 0.01dB resolution above 10mV.

The 100kHz bandwidth covers well past the audio range. The optional RF probe extends the bandwidth to 250MHz.

The relative reference allows nulling out circuit voltage offsets or lead resistances. By nulling out power supply voltages or circuit outputs, drifts or changes can be displayed. Combined with the dB function, it can be used to make fast gain-stage measurements.

With the Model 175A’s digital calibration, all calibration factors are stored in non-volatile memory, allowing calibration to be done electronically without manual adjustments.

The IEEE-488 interface option offers range programmability on volts and ohms, TALK/LISTEN capability, trigger, SRQ, and other commands. Combined with the digital calibration feature, calibration can be performed on the bus in as little as two minutes.

A REL level can be established for any measurement function (Volts, Ohms, Amps, and dB) and is effective only on that function. Changing functions will not affect a REL level already established. However, if another REL level is set, the previous REL level will be cancelled.

The Model 175A may be operated from either 105-125 V or 210-250 V, 50 or 60 Hz power sources. If the line voltage setting of the instrument needs to be changed, set the line voltages switch, located on the rear panel, in the desired position