User’s Guide
MultiTecTM Series
Digital MultiMeters with PC Interface
Models: MT310
MT320
MT330
Tech Support
Hotlines
781-890-7440
ext. 200
extech@extech.com
WARRANTY
EXTECH INSTRUMENTS CORPORATION warrants this instrument to be free of defects in parts and workmanship for
three years from date of shipment (a six month limited warranty applies on sensors and cables). If it should become
necessary to return the instrument for service during or beyond the warranty period, contact the Customer Service
Department at (781) 890-7440 ext. 210 for authorization. A Return Authorization (RA) number must be issued before
any product is returned to Extech. The sender is responsible for shipping charges, freight, insurance and proper
packaging to prevent damage in transit. This warranty does not apply to defects resulting from action of the user such as
misuse, improper wiring, operation outside of specification, improper maintenance or repair, or unauthorized modification.
Extech specifically disclaims any implied warranties or merchantability or fitness for a specific purpose and will not be
liable for any direct, indirect, incidental or consequential damages. Extech's total liability is limited to repair or replacement
of the product. The warranty set forth above is inclusive and no other warranty, whether written or oral, is expressed or
implied.
REPAIR AND CALIBRATION SERVICES
Extech offers complete repair and calibration services for all of the products we sell.
For periodic calibration, NIST certification or repair of any Extech product, call customer
service for details on services available. Extech recommends that calibration be performed
on an annual basis to insure calibration integrity.
Copyright © 1999 Extech Instruments Corporation. All rights reserved including the
right of reproduction in whole or in part in any form. Version 1.2 4/00
Introduction
Congratulations on your purchase of Extech model MT310, MT320, or MT330 digital multimeter. Properly used, this meter
will provide many years of reliable service. All models measures AC/DC Voltage/Current, Resistance, Frequency and
Capacitance. All models are Autoranging and include a PC Interface feature.
The MT320 and MT330 also measure
temperature. The Model MT330 is True RMS responding.
Safety
International Safety Symbols
Refer to the manual Hazardous voltages Double insulation
for further information may be present.
UL Listed
The UL mark does not indicate that this product has been evaluated for the accuracy of its readings.
Safety Precautions
1. Improper use of this meter can cause damage, shock, injury or death. Read and understand this user manual
before operating the meter.
2. Make sure any covers or battery doors are properly closed and secured.
3. Always remove the test leads before replacing the battery or fuses.
4. Inspect the condition of the test leads and the meter itself for any damage before operating the meter. Repair any
damage before use.
5. Do not exceed the maximum rated input limits.
6. Use great care when making measurements if the voltages are greater than 25VAC rms or 35VDC. These
voltages are considered a shock hazard.
7. Always discharge capacitors and remove power from the device under test before performing Capacitance, Diode,
Resistance or Continuity tests.
8. Remove the battery from the meter if the meter is to be stored for long periods.
9. To avoid electric shock, do not measure AC current on any circuit whose voltage exceeds 250V AC.
10. Voltage checks on electrical outlets can be difficult and misleading because of the uncertainty of connection to the
electrical contacts. Other means should be used to ensure that the terminals are not "live".
Specifications
Function Ranges Accuracy
400.0mV
±(0.3% reading + 5 digits)
4.000V, 40.00V, 400.0V,
±(0.1% reading + 5 digits)MT330
±(0.3% reading + 5 digits)MT320
±(0.5% reading + 5 digits)MT310
DC Voltage
(V DC)
1000V
±(0.5% reading + 5 digits)
100.0-400.0mV
±(1.5% reading + 5 digits)
4.000V,40.00V, 400.0V
±(1.0% reading + 5 digits) (40Hz to 1kHz)
AC Voltage
(V AC)
(Model MT330
True RMS)
700.0V
±(1.5% reading + 5 digits)
400.0µA, 4000µA, 40.00mA, 400.0mA ±(1.2% reading + 10 digits)
DC Current
(A DC)
20.00A
±(2% reading + 10 digits)
400.0µA, 4000µA, 40.00mA, 400.0mA ±(1.5% reading +10 digits) (40Hz to 1kHz)
AC Current
(A AC)
(Model MT330
True RMS)
20.00A
±(2% reading + 10 digits)
Function Ranges Accuracy
400.0Ω, 4.000kΩ, 40.00kΩ, 400.0kΩ, 4000kΩ ±(0.5% reading + 10 digits)
Resistance
40.00MΩ ±(1% reading + 5 digits)
500.0mHz Not specified Frequency
5.000Hz, 50.00Hz, 500.0Hz, 5.000kHz, 50.00kHz,
500.0kHz, 5.000MHz, 10.00MHz
±(0.1% reading + 2 digits)
(250mVac peak minimum)
Capacitance 40.00nF, 400.0nF, 4.000uF, 40.00uF, 100.0uF
± (2% reading + 10 digits)
0.0-212.0°F ± (3° + 5 digits)
212.0 – 400.0°F
Temp °F
(MT320 and
MT330 only)
400.0 - 2000°F
± (3% reading + 5 digits)
-20.0 – 100.0°C ± (3° + 5 digits)
100.0 – 400.0°C
Temp °C
(MT320 and
MT330 only)
400.0 - 1370°C
± (3% reading + 5 digits)
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