10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com
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Section I – Introduction
Purpose and Function
The AVM-2000 is a multi-range analog DC Voltmeter/Nullmeter. It has 21 bipolar ranges from ± 100
nanovolts full scale to ± 1000 volts full scale in a 1-3-10 sequence. The AVM-2000 functions either as an
isolated null detector or as an isolated analog voltmeter.
Key functions of the AVM-2000:
The AVM-2000 is a freestanding bench instrument housed in a protective metal enclosure. A single
unit may be mounted in a standard 19 inch rack using a conventional rack shelf.
Bail front feet allow the user to tilt the instrument for optimal viewing.
Voltage readings are displayed on a taut-band, zero-center, 4½ inch, mirror-backed, dual-scale
analog meter.
A rotary control provides selection of the instrument’s 21 ranges.
Instrument status (range, offset voltage, filter settings, battery condition, input impedance
selection, etc.) are displayed on a front panel LCD.
The AVM-2000 may be operated from the AC power line, an internal rechargeable battery or an
external DC source of 12 – 30 V. The instrument’s internal battery charger operates any time the
AVM-2000 is connected to a power source and the instrument is in a standby mode .
Voltages to be measured are applied to the AVM-2000 via low-thermal EMF front panel input
terminals—HI and LO. A GUARD terminal is provided to connect input wiring shields.
A FILTER selection feature allows the operator to choose signal filtering from 0.1 to 100 seconds to
improve measurements.
An OFFSET feature allows the user to offset a wide range of input voltages.
An OPERATE/ZERO switch allows the user to disconnect the HI input terminal from the amplifier
input and short the amplifier input to input common (LO). The user may select any one of 4
different input impedances for ranges below 3 mV and either 10 or 100 M
Ω
for ranges of 3 mV to
300 V. The 1 kV range input impedance is fixed at 100 M
Ω
.
A multi-mode INPUT OFFSET control allows the user to adjust the instrument’s zero (voltage) for
the current range, to inject an input offset current of up to ± 2.5 nA to offset the effects of input
bias currents on high impedance voltage sources or to select the digit of offset voltage to be
changed.
A two-terminal rear panel output is provided for use with external devices such as chart recorders,
remote data acquisition systems, digital readouts, etc. This output allows the AVM-2000 to function
as a high sensitivity instrumentation amplifier with gains that are the inverse of the input
attenuator settings. These two terminals are an ISOLATED OUTPUT. A third rear panel terminal is
connected to the case. A front panel control allows adjustment of the full scale output level from ±
0.5 volts to ± 1.5 volts.
Capabilities
The AVM-2000 is designed for the calibration laboratory. By utilizing a unipolar, high gain, low drift
amplifier coupled with the ability to attenuate or amplify the input voltage makes the AVM-2000 ideal for
nulling applications/calibrations. This is ideal for comparing an unknown to a known (comparing a 10 V
source to a voltage standard).
