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MULTIMETER (digital)

Manufacturer: Keithley
Model: 179A
Cost: $705 (Nov. 1986)

Description

Versatile high precision meter capable of five different functions, i.e. true rms AC and DC currents, true rms AC and DC voltages, and resistance. Measured values are displayed on a digital readout.

Specifications

DC Voltage
Ranges	200 mV to 1200 V in 5 ranges
Accuracy	±(0.04% of reading) on 200 mV scale
	±(0.04% of reading) on other scales
Input Resistance	10 Mohms, all ranges

DC Current
Ranges	200 uA to 20 A in 6 ranges
Accuracy	2 uA through 2000 mA ± (0.02% of reading)
	20 A ± (0.5% of reading)
Resistance	200 uA scale: 1 kOhm
	2 mA scale: 100 Ohm
	20 mA scale: 10 Ohm
	200 mA scale: 1 Ohm
	2000 mA scale: 100 mOhm
	20 A scale: 10 mOhm

Resistance
Ranges	20 kohm to 20 Mohm in 5 ranges
Accuracy (HI)	± (0.1%) 20 MOhm scale
	± (0.04%) other scales
Accuracy (LO)	± (0.15%)
Applied Voltage (HI)	2V
Applied Voltage (LO)	0.2V

AC Volts
Ranges	200 mV through 1000 V in 5 ranges
Accuracy	± (0.7% of reading) on 300 mV scale
	± (0.6% of reading) on 2V scale
	± (0.5% or reading) on other scales
Freq. range	100 Hz - 10 Hz
Input Impedance	1 Mohms shunted by less than 75 pF.

AC Current
Ranges	200 uA through 20 A in 6 scales
Accuracy	± (1% = 15 digits)
Freq. range	45 Hz - 10 kHz
Resistance	200 uA scale: 1 kOhm
	2 mA scale: 100 Ohm
	20 mA scale: 10 Ohm
	200 mA scale: 1 Ohm
	2000 mA scale: 100 mOhm
20 A scale	10 mOhm

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Operating Instructions

Obvious, except for the "Hi/Lo" switch. When used as an ohmmeter, when the switch is in the "HI" position it applies 2V across the resistance to be measured, when in the "LO" position it applies 0.2V across the resistance. The "HI" position is automatic for the 2 kOhm ranges, the "LO" position is automatic for the 20 MOhm range, and at intermediate ranges is user-selectable. The "HI" position provides greater accuracy, but the voltage is sufficient to cause unwanted effects on some components, such as forward conduction of semiconductor junctions.

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keywords: voltmeter, voltage measurement device, resistance measurement device, ohmeter, electrical measurement device, dmm, current measurement device, ammeter.

Document created October 1988. Original author: Unknown.
Last updated 01/28/05. Revised by Phil Scolieri.