General GT320 User Manual

WIRELESS DATA LOGGING

MULTIMETER

WITH DOT MATRIX LCD

PLUS NCVD/NCCD

USER’S MANUAL

GT320

Please read this manual carefully and thoroughly before using this product.

(laptop not included)

(includes RD330
Remote Display
with Memory)

TABLE OF CONTENTS

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 –4

Key Features & Specs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

What’s in the Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Safety Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 –8

Product Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 – 11

Setup Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Install Battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Insert Test Leads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Operating Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 – 19

General Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Measuring DC or AC Voltage . . . . . . . . . . . . . . . . . . . . . 12 – 13

Measuring Resistance or Capacitance . . . . . . . . . . . . . . . . . 13

Checking the Integrity of a Diode or the . . . . . . . . . . . . . . . . 14

Continuity of a Circuit

Measuring DC or AC Current . . . . . . . . . . . . . . . . . . . . . 14 – 15

Non-Contact AC Voltage/Current Detection (NCVD/NCCD). . . 15

Going Wireless. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 – 19

Transmitting Data to a PC . . . . . . . . . . . . . . . . . 16 – 18

Receiving and Displaying Data from a

Second GT320 or a GT310. . . . . . . . . . . . . . . . . 18 – 19

Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 – 22

Maintenance Tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Optional Accessories and Replacement Parts . . . . . . . . . . . . . . . 22

Warranty Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Return for Repair Policy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

2

INTRODUCTION

Thank you for purchasing General Tools & Instruments’ GT320
Wireless Data Logging Multimeter with Dot Matrix LCD plus
NCVD/NCCD. Please read this manual carefully and thoroughly before
using the instrument.

The GT320 can measure—with better than 1% accuracy, in most
cases—the six electrical parameters (DC voltage, AC voltage, DC
current, AC current, resistance and capacitance) that most
professional-grade multimeters measure. Like other multimeters, it
can also be used to verify the integrity of a diode and to check for
continuity within a circuit. However, the GT320 has two safety and
convenience features—NCVD/NCCD and wireless device-to-device
communication—that many comparably priced multimeters lack.

NCVD and NCCD—non-contact voltage and current detection—
empower the electrician in several valuable ways. For example, the
meter’s integrated NCVD sensor can quickly determine which wire in
a group is “live” without the user having to “tap” all the lines. It is so
sensitive it can pinpoint the location of a 30VAC line inside PVC conduit
behind a wooden wall. The NCCD sensor in the GT320 is equally
impressive. It can detect as little as 500 mA of current flowing behind
a concrete or plaster wall, under a floor, above a ceiling, in an
overhead line, or in a buried underground cable. The NCCD sensor can
also detect RF signals (such as from a walkie-talkie) and magnetic
fields.

Wireless communication offers an additional level of safety and
convenience. Being able to read the meter’s measurements from up to
33 ft. (10m) away (on a PC, on a second multimeter in the GT Series,
or on the included RD330 Remote Display with Memory) lets the
electrician observe the effect of throwing a switch or changing a
setting on a piece of equipment without having to be near it. If a
system or piece of equipment operates at high voltages, remote
display makes troubleshooting it safer. If multiple changes to another
system or piece of equipment are needed to troubleshoot a problem,
remote display may save an electrician considerable time by allowing
him or her to immediately see the results of each step taken without
having to shuttle between two areas.

3

The GT320 can be part of three different kinds of wireless
communication schemes.

1. The meter includes a small USB receiver—called a dongle—that
enables any PC to display all the information shown on the unit’s
display. The “Going Wireless” section of this user’s manual provides
instructions for downloading the software needed to activate this
connection. The advantage of using a PC’s monitor to display the
meter’s measurements is readability: readings sent to the screen
of a laptop or desktop computer are several inches high—large
enough to be visible across a room.

2. With two GT320s or one GT320 and one GT310 (essentially, a
GT320 with a dual 7-segment display instead of a dot matrix
display), each meter can be configured to display its own
measurements on its upper readout, and receive and display the
other meter’s measurements on its lower readout. Both models
include the wireless transceiver module needed to “share” readings
remotely—improving safety in the process—in this way.

3. For even greater remote display versatility, use the GT320 with the
included RD330 Remote Display with Memory. The standalone
4 in. x 4 in. unit, which uses the same wireless transceiver module
as the GT320 and GT310, can not only display the readings of two
multimeters simultaneously on its own dual LCD with 0.67 in.
(17mm) high digits; it can also memorize up to 99 readings or pairs
of readings. In addition to its memory, the advantages of using the
RD330 as a remote GT320 display are compactness and portability.

Another key feature of the GT320 is its pair of double-insulated fused
test leads. Like NCVD/NCCD and wireless device-to-device
communication, the fuse in the red test lead offers the electrician
safety and convenience. It not only prevents excessive currents from
flowing through the meter, potentially injuring the user and damaging
the meter. In addition, the position of the fuse makes changing it fast
and easy. In many other multimeters, changing a blown fuse requires
the user to open up the instrument.

The red lead has a unique square plug. The meter's use of a square
(+) jack prevents potentially damaging use of industry-standard round,
non-fused leads.

4

KEY FEATURES & SPECS

• 12 functions, 33 ranges

• Measures AC/DC voltage (up to 750VAC/1000VDC), AC/DC current

(up to 400mA), resistance (up to 40m

Ω) and capacitance (up to

100 uF)

• Verifies integrity of diodes and checks circuits for continuity

• Includes double-insulated test leads; red lead has fast-acting

ceramic fuse rated at 500mA/500V and unique square plug.
Corresponding square jack on meter prevents potentially damaging
use of round, non-fused leads.

• Includes non-contact AC voltage and current detection (NCVD and

NCCD) sensors with beeper

• CAT III 1000V, CAT IV 500V ETL certified

• Wirelessly interfaces to PC at 2.4 GHz from up to 33 ft. (10m) away

via included USB dongle

• Includes transceiver module for wirelessly interfacing to second

GT320 or GT310 (functionally identical model with 7-segment
display) or included RD330 Remote Display with Memory

• Choice of 10 channels for each wireless link

• Flexible, 3-3/4 digit (4000 count), dot matrix LCD with 0.67 in.

(17mm) high digits

• Auto ranging or manual ranging

• Data hold and zero adjust buttons

• Fifteen-minute Auto Power Off function

• Low battery indicator

• Ergonomic design with rugged rubber housing

5

WHAT’S IN THE BOX

The GT320 comes in a black soft pouch with a belt loop inside a box.
Also inside the pouch are:

• A pair of fused test leads (General Part No. TL300)

• A USB dongle (General Part No. GTSF05) for wireless viewing of the

meter’s display on a PC. Software for enabling the dongle to display
the GT310's readings on a PC is downloadable from the GT320 page
of General’s website (www.generaltools.com).

• An RD330 Remote Display with Memory with its own user’s manual

• A “9V” battery

• This user’s manual

SAFETY INSTRUCTIONS

!

WARNING

To avoid possible electric shock or personal injury, and to avoid
damaging the meter or the equipment under test:

• Do not use the meter in any way not detailed in this manual or the

meter’s safety features may be compromised.

• Before using the meter, inspect the case. Do not use the meter if it is

damaged. Look for cracks or missing plastic. Pay particular attention
to the insulation around the connectors.

• !

WARNING

Inspect the test leads for damaged insulation or
exposed metal. Check the test leads for continuity. Replace damaged
test leads before using the meter.

• For safety reasons, you cannot switch to using unfused test leads to
make measurements.

YOU MUST USE FUSED TEST LEADS

fitted with
a fast blow fuse rated at 500mA/500V. Using unfused test leads also
voids the limited warranty.

• Verify the meter’s operation by measuring a known voltage. Do not
use the meter if it operates abnormally. Protection may be impaired.
When in doubt, have the meter serviced.

• !

WARNING

Do not apply more than the rated voltage, as marked on

the meter, between the terminals or between any terminal and ground.

6

• !

WARNING

Do not measure voltages above 600V in CAT III

installations.

• !

WARNING

Do not measure voltage with the rotary dial pointing to
the resistance (ohms), current, capacitance or NCVD or NCCD
positions. Never measure current with the dial pointing to the
resistance (ohms), capacitance or NCVD or NCCD positions.

• Use caution when working with voltages above 42V ACrms, or 60V
DC. These voltages pose a shock hazard.

• Use the proper terminals, function, and range for all measurements.

• !

WARNING

Do not operate the meter around explosive gas, vapor,

or dust.

• !

WARNING

When using the probes, keep your fingers behind the
finger guards. Do not touch the metal probes of the test leads when
making a measurement.

• When making connections, connect the black (–) test lead before
connecting the red (+) test lead; when disconnecting, disconnect the
red (+) test lead before disconnecting the black (–) test lead.

• Disconnect circuit power and discharge all high-voltage capacitors
before measuring/testing resistance, continuity, diodes, or
capacitance.

• For all DC functions in both auto ranging and manual ranging modes,
to avoid the risk of shock due to possible improper reading verify the
presence of any AC voltages by first using the AC voltage
measurement function. Then select a DC voltage range equal to or
greater than the AC range.

• Before measuring current, turn off power to the circuit before
connecting the meter.

• Do not operate the meter with the case (or part of the case)
removed.

• Replace the battery as soon as the low battery indicator “ ”
appears. Operated with a weak battery, the meter might produce
false readings that could lead to electric shock and personal injury.

• Remove the test leads from the meter before opening the meter
case or battery compartment.

7

PRODUCT OVERVIEW

Fig. 1 shows the labels and positions of the controls, indicators and
connectors on the front and top of the GT320. Familiarize yourself with
their functions, as explained below, before moving on to the Setup
Instructions and Operating Instructions.

1. Replaceable 2.4GHz transceiver module (on top of unit)

2. NCCD sensor (on top of unit)

3. NCVD sensor (on top of unit)

4. Dot matrix LCD

5. Backlight

8

GT320

Fig. 1. The
GT320’s controls,
indicators and
connectors

6. Two-function Range button:

a) In all measurement modes, press briefly to exit Auto ranging

mode (default) and enter Manual Ranging mode. With two

exceptions (the highest voltage ranges), each subsequent brief
press of the button decreases the measurement sensitivity
(increases the full-scale measurement range) by a factor of
10 (one decimal place)

b) In all measurement modes, press and hold for >3 seconds to

exit Manual Ranging mode and enable Auto ranging

7. Multi-function Power/Tx/Rx/Ax button:

a)

Press briefly to enable transmission mode; Tx

appears on

display

b) Press briefly a second time to enable reception mode;

Rx

appears on display

c) Press briefly a third time to enable transmission and

reception mode:

Tx

and

Rx

both appear on display

d) Press briefly a fourth time to disable transmission and

reception (

Tx

and

Rx

both disappear)

e) With rotary dial in any position but OFF, press and hold for

>3 seconds to power meter on or off.

8. Adj. Zero button (press briefly to reset readout)

9. Two-function Buzzer button:

a) Press briefly to turn backlight on/off

b) Press and hold for 3> seconds to turn beeper on/off

( appears/disappears at right of display)

10. Multi-function Select/0-9 button:

a) In voltage and current measurement modes, press briefly to

switch from DC measurement (default) to AC measurement

b) With rotary dial set to position, press briefly to

switch from resistance measurement mode (the default) to

diode integrity check mode. Press briefly again to switch to
continuity check mode. Press briefly again to switch to
capacitance measurement mode. Press briefly again to return
to resistance measurement mode

9

c) In channel entry mode (with channel number flashing in top

or bottom readout), press briefly to increment channel

number. Pressing the button briefly with the display showing

CH-9

resets readout to

CH-0

11. Two-function Hold/CH button:

a) Press briefly to hold (freeze) reading(s). Press briefly again to

release hold.

b) Press and hold for >3 seconds to enter Hi channel entry

mode. In Hi channel entry mode, press briefly to enter Lo
channel entry mode. In both modes, if no entry is made within
10 seconds, readout(s) revert to showing real-time
measurements.

12. Rotary dial

13. COM jack for black (negative) test lead

14. Jack for red (positive) test lead

15. Battery compartment (on back of unit)

16. Black (negative) test lead

17. Red (positive) test lead. Contains fast-acting ceramic fuse rated

at 500mA/500V

18. Protective caps for test leads

The table below explains the symbols and abbreviations used on the
meter and in this manual.

Electrical Symbols Used On the Meter and In This Manual

10

Adjust reading to zero
Wireless transmit mode
Wireless receive mode
Alternating voltage / current
Direct voltage / current
Negative
Freeze / Hold reading

Tx (where X = 0-9)
Rx (where X = 0-9)

HOLD

SETUP INSTRUCTIONS

INSTALL BATTERY

The battery of your GT320 may or may not already be installed. If the
display remains dark after you turn the rotary dial to any position other
than

OFF

:

• Return the rotary dial to the

OFF

position.

• Flip the meter over and lift the bottom of the yellow foldaway stand
on the back with your fingertip or a flat-blade screwdriver.

• Loosen and remove the two Phillips-head screws securing the
rectangular yellow plastic battery compartment cover. Set the cover
aside.

• Install a fresh “9V” battery in the compartment, with the (+) terminal
(anode) on the right (with the back of the meter facing you)..

• Replace the battery compartment cover and resecure it with the two
screws.

INSERT TEST LEADS

Plug the red (fused) test lead into the right (red) socket on the front of
the meter and plug the black lead into the black socket. Remove the
clear plastic caps from the tips of the leads.

11

Diode
Auto ranging
Low battery
Overvoltage Category 3
Overvoltage Category 4
Ground
Beeper
Non-Contact Voltage (AC) Detection
Non-Contact Current (AC) Detection

OPERATING INSTRUCTIONS

GENERAL INSTRUCTIONS

• To hold (freeze) a reading, briefly press the

Hold/CH

button.

• To turn the beeper on or off, briefly press the

Buzzer

button.

• To turn the backlight on or off, press and hold the

Buzzer

button for

>3 seconds.

• The meter is equipped with an Auto Power Off (APO) function that is
triggered by 15 minutes with no input. It cannot be disabled. To
“wake up” the meter in the same measurement state (but not
transmission/reception state) it was in when the APO function
activated, briefly press the Power/Tx/Rx/Ax button (Callout 7 of
Fig. 1). You need not turn the rotary dial to power the meter on again.

• Each time you finish using the meter, turn the rotary dial to the OFF
position.

• To ensure the accuracy of measurements, make sure that the points
touched by the test probes are free from dirt, oil, lacquer, and similar
substances.

• Until you enable wireless transmission
and/or reception, the meter will function in
“normal” operating mode with a display
that looks like this:

MEASURING DC OR
AC VOLTAGE

F! Do not exceed maximum ratings. Do not contact circuits or

parts of circuits in which voltages with amplitudes greater than 25V
ACrms or 35VDC may be present.

Turn the rotary dial to the V position. The unit mV will appear at the
right of the display. The symbol will appear at the top left of the
display, below the word

AUTO

, indicating that the meter is ready to

measure DC voltage in Auto ranging mode.
To measure AC voltage, briefly press the

Select/0-9

button to change

the symbol to

~.

12

Touch the test leads to two points in a circuit at different electric
potential. A minus sign (–) at the left of the reading indicates a
negative voltage.

To switch to Manual Ranging mode, press the Range button briefly
once to remove the AUTO indication from the top left of the display.
With two exceptions (the highest ranges), each subsequent brief press
of the button decreases the measurement sensitivity (increases the
full-scale measurement range) by a factor of 10 (one decimal place). If
the measured voltage is greater than the full-scale range, the readout
will be OL. To return to Auto ranging mode, press and hold the Range
button.

In AC or DC voltage measurement mode, the meter presents an input
impedance of >10M

Ω to the circuit under test.

MEASURING RESISTANCE OR CAPACITANCE

Before measuring resistance or capacitance, be sure to remove power
from the circuit under test and to discharge any high-voltage
capacitors in it.

Turn the rotary dial to the

Ω position. The unit MΩ will appear at the

right of the display. The word AUTO will appear at the top left,
indicating that the meter is in Autoranging mode.

To measure the resistance between two points of a circuit, touch the
test leads to those two points.

To measure the capacitance between two points of a circuit, press the
Select/0-9 button briefly three times to change the M

Ω symbol to the

letter F. Then touch the test leads to the two points of interest.
To switch to Manual Ranging mode, press the Range button briefly

once to remove the

AUTO

indication from the top left of the display.
Each subsequent brief press of the button decreases the measurement
sensitivity (increases the full-scale measurement range) by a factor of
10 (one decimal place).

13

CHECKING THE INTEGRITY OF A DIODE
OR THE CONTINUITY OF A CIRCUIT

Before checking a diode or checking for continuity, be sure to remove
power from the circuit under test.

Turn the rotary dial to the

Ω position. With the symbol MΩ at the right

of the display, briefly press the

Select/0-9

button once to call up the

diode symbol .
Connect the red test lead to the anode (positive terminal) of the diode

to be tested, and the black test lead to its cathode (negative terminal).
Read the forward bias voltage value on the display. A typical silicon
diode has a forward bias voltage between 0.7 and 0.99V. A typical
germanium diode has a forward bias voltage between 0.3 and 0.36V.

A 0V reading in both directions indicates a shorted diode. An OL
reading indicates an open diode. In either case, the diode is defective
and should be replaced. An OL reading also may indicate that the
polarity of the test leads is reversed. This test can be used to
distinguish the anode and cathode of a diode.

To enter Continuity Check mode, briefly press the

Select/0-9

button
once with the diode symbol showing on the display. This will
change the diode symbol to the

Ω unit. If the icon is not visible at

the right of the display, activate the beeper by pressing the Buzzer
button.

In Continuity Check mode, the initial reading will be

OL

. Touch the test
leads to any two points in the circuit. If the resistance between the
points is <30

Ω, the meter will produce a long beep.

MEASURING DC OR AC CURRENT

F! The circuit to be tested may not carry a voltage in excess of

1000VDC or 750VAC. Applying a current of >500 mA will blow the fuse
in the red test lead. To remove the fuse, unscrew the top of the red
lead. Replace the blown fuse with a fast-acting ceramic fuse with a
rating of 500mA/500V.

Turn the rotary dial to the uA or mA position, depending on the
expected amplitude. The unit uA or mA will appear at the right of the
display. The word AUTO will appear at the top left, indicating that the
meter is in Auto ranging mode.

14

The default mode is DC current measurement (indicated by the
symbol near the top left of the display). To measure AC current, press
the

Select/0-9

button to change the symbol to ~.

Touch the test leads to two points in the circuit and read the displayed
value. A minus sign (-) at the left of the reading indicates a negative
value.

If applying current produces a reading of OL in uA Measurement
mode, switch to mA Measurement mode.

To switch to Manual Ranging mode, briefly press the Range button
once to remove the AUTO indication from the top left of the display.
Each subsequent press of the Range button decreases the
measurement sensitivity (increases the full-scale measurement range)
by a factor of 10 (one decimal place). If the measured current
amplitude is greater than the full-scale range, the display will show
OL. To return to Auto ranging mode, press and hold the Range button.

NON-CONTACT AC VOLTAGE/CURRENT DETECTION
(NCVD/NCCD)

Turn the rotary dial to the NCVD or NCCD position. Move the meter at
least several feet away from all wiring and briefly press the Adj. Zero
button. This maximizes the sensitivity of the NCVD or NCCD sensor.

Holding the meter in your hand, slowly move its top toward the known
or suspected source of voltage or current. As the meter approaches
the potential source of AC voltage or current, the display reading will
increase and the beeper will increase its speed. The display reading is
a relative value with no units. When the reading peaks, briefly press
the Hold button to freeze it.

To use the meter to distinguish a true “live” wire from a “ghost” live
wire, turn the rotary dial to the NCVD position, move the meter away
from all wiring, and press the Adj. Zero button. Plug the red test lead
into the red front-panel socket. Touch the tip of the lead to the
suspected live wire and note the display reading. Also touch other
suspected sources. The true live wire will produce the highest reading.

15

GOING WIRELESS

Transmitting Data to a PC

Use the following procedure to enable your GT320 to display its
readings on a PC monitor using digits that are several inches high—
large enough to be visible across a room.

You will first download and install the software that enables your
GT320 to communicate with the GTSF05 wireless USB receiver
(dongle) supplied with the meter. The final few steps of the procedure
explain how to match the software’s receiving channel to the
transmitting channel of the GT320.

1. Go to www.generaltools.com and enter GT320 in the SEARCH box.

2. On the GT320 page, click the “Download General Tools Product

Software” button.

3. Save <GTSF05_Setup.zip> to your desktop.

4. Click the Open button on the icon.

5. Highlight <GTSF05_Setup.msi>

6. Use a utility like WinRAR to extract <GTSF05_Setup.msi> to your

desktop.

7. Double-click <GTSF05_Setup.msi>; doing so opens a window titled

“Welcome to the DMMD_PCViewSetupWizard”. Click Next.

8. Click Next to install <DMMD_PCView> on your computer in a folder

named <C:\ProgramFiles(x86)\DMMD_PCView\>. To install the
program elsewhere, click Browse and choose an alternate location.

9. The next window confirms the installation. Click Next to continue.

10. The next window is titled <Installing DMMD_PCView>. Installation

typically takes less than 1 minute.

11. Click

Close

to exit.

12. Note that a GTSF05.exe icon has been added to your PC’s desktop

and Start button.

13. Double-click the icon to open the program.

14. A “Tips” window will appear asking you to “Please insert GTSF05

dongle!”

16

15. Plug the dongle into any open USB port on your computer. Doing so

will cause the following screen to appear.

16. On the meter, press the Power/Tx/Rx/Ax button once.

TO

(the
default transmitting channel) will appear at the right of the display.
You will next change the transmitting channel number to 1. To do
so, press and hold the

Hold/CH

button. The display will show

T = 0

(with the “0” flashing) over

R = 0

. Quickly (within 10 seconds)

press the

Select/0-9

button once to advance the channel counter
to “1”. Quickly save the setting by pressing and holding the
Hold/CH button.

17. On the “DMMD_PCView GTSF05” screen, click the Scan CH
button. The program will begin scanning Channels 0 through 9.
Scanning will stop when the GT320’s transmission on Channel 1 is
detected, causing the  button to turn green.

18. Click again on the green  button to produce a display like the
following:

19. The reading on the DMMD_PCView screen will continue to
duplicate the contents of the GT320’s readout.

17

Receiving and Displaying Data from a Second GT320 or a GT310

To configure your GT320 to receive display measurements and
indications from another GT320 or a GT310 wireless multimeter, use
the Power/Tx/Rx/Ax button.

When the meter is powered on, the default setting is no communication.

To enable transmission, briefly
press the Power/Tx/Rx/Ax button
once. The term

T0

will appear and

the display will look like this:

To enable reception, briefly press
the Power/Tx/Rx/Ax button a
second time. The term

T0

will be replaced by the term R0. In “receive
only” mode, your GT320 will not display any of its own measurements;
it will only display measurements from a second wireless multimeter.

Immediately after you enable
receive mode, your GT320 will
operate in “standby receive mode”
until you synchronize its receiving
channel with the transmitting
channel of the other meter. Before
you synchronize the two meters,
the display will look like this:

After you synchronize the two
multimeters, the new display will
duplicate the data shown on the
second meter and look like this:

To match the receiving channel of your GT320 to the transmitting
channel of the second multimeter, press and hold the Hold/CH
button, and then press it briefly to cause the lower readout to show
R = 0. Quickly (within 10 seconds), press the

Select/0-9

button as
many times as needed until the receiving channel number of your
GT320 matches the transmitting channel number of the second
multimeter.

To enable transmission and reception, briefly press the
Power/Tx/Rx/Ax button a third time. This will cause both terms

(Tx and Rx) to appear at the right of the display. The upper reading will

18

represent data from your GT320 and
the lower reading will represent data
from the second multimeter. The
composite display will look like this:

SPECIFICATIONS

GENERAL SPECIFICATIONS

• Maximum Voltage between Terminal and Ground: 1000V/CAT III;

500V/CAT IV

• Test Leads Characteristics: Double sheath, soft PVC wire fitted with

500mA/500V fast-acting ceramic fuse measuring 6mm across
x 32mm long. Red lead also has unique square plug compatible with
(+) jack on meter.

• Display Type: Flexible, 3-3/4 digit (4000 count), dot matrix LCD with

0.67 in. (17mm) high digits

• Sampling Rate: 3 times 1 sec.

• Maximum Voltage Measurement: DC 1kV , AC 750V

• Input Impedance in Voltage Measurement Mode: >10M

Ω

• Maximum AC/DC Current Measurement: 400mA

• Maximum Resistance Measurement: 40M

Ω

• Maximum Capacitance measurement: 100uF

• Diode Integrity Test Voltage: 1.5V

• Continuity Check Threshold: <30

Ω with beeper

• Non-contact AC Voltage Detection Range: 50V to 1 kV or higher;

100 to 250V in “Live or Ghost” mode

• Non-contact AC Current Detection Range: 100mA to 1000A or higher

• Transmission/Reception: Half-duplex; Ten channels centered on

2.4GHz

• Communication Range: >33 ft. (10m)

• Auto Power Off Interval: 15 minutes

• Backlight Fadeout Interval: 90 seconds

• Power Source: (1) “9V” battery

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• Power Consumption: <3mA (standby mode);

<20mA (normal operating mode); <25mA (transmitting mode);
<60mA (receiving mode); <80mA (transmit + receive mode)

• Dimensions (Excluding Test Leads):

7.1 x 3.7 x 2.1 in. (180 x 95 x 54mm)

• Weight (Excluding Battery): 1 lb. (450g)

MEASUREMENT RANGES,
RESOLUTIONS & ACCURACIES

AC Voltage (Manual Range)

Range Resolution Accuracy

0-400mV 0.1mV ±0.6% of reading ±3 digits

0-4V 0.001V ±0.6% of reading ±3 digits

0-40V 0.01V ±0.6% of reading ±3 digits

0-400V 0.1V ±0.6% of reading ±3 digits

0-750V 1V ±1.0% of reading ±5 digits

DC Voltage (Manual Range)

Range Resolution Accuracy

0-400mV 0.1mV ±0.6% of reading ±2 digits

0-4V 0.001V ±0.6% of reading ±2 digits

0-40V 0.01V ±0.6% of reading ±2 digits

0-400V 0.1V ±0.6% of reading ±2 digits

0-1000V 1V ±0.8% of reading ±2 digits

AC Current (uA Setting, Manual Range)

Range Resolution Accuracy

0-400uA 0.1uA ±0.15% of reading ±5 digits

0-4mA 1uA ±0.15% of reading ±5 digits

DC Current (uA Setting, Manual Range)

Range Resolution Accuracy

0-400uA 0.1uA ±0.12% of reading ±3 digits

0-4000uA 1uA ±0.12% of reading ±3 digits

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AC Current (mA Setting, Manual Range

Range Resolution Accuracy

0-40mA 0.01mA ±0.15% of reading ±5 digits

0-400mA 0.1mA ±0.15% of reading ±5 digits

DC Current (mA Setting, Manual Range)

Range Resolution Accuracy

0-40mA 0.01mA ±0.15% of reading ±5 digits

0-400mA 0.1mA ±0.15% of reading ±5 digits

Resistance (Manual Range)

Range Resolution Accuracy

0-400

Ω

0.1

Ω

±0.7% of reading ±5 digits

0-4k

Ω

0.001k

Ω

±0.6% of reading ±2 digits

0-40k

Ω

0.01kΩ ±0.6% of reading ±2 digits

0-400k

Ω

0.1kΩ ±0.7% of reading ±2 digits

0-4M

Ω

0.001MΩ ±1.5% of reading ±5 digits

0-40M

Ω

0.01M

Ω

±2.0% of reading ±6 digits

Capacitance (Manual Range)

Range Resolution Accuracy

0-52nF 0.01nF ±3% of reading ±7 digits

0-520nF 0.1nF ±3% of reading ±5 digits

0-5.2uF 0.001uF ±3% of reading ±5 digits

0-52uF 0.1uF ±10% of reading ±10 digits

0-100uF 0.1uF ±10% of reading ±10 digits

Diode Integrity Check

Range Resolution Accuracy

1.5V Open 0.001V ±10% of reading ±5 digits

Continuity Check

Range Resolution Accuracy

400Ω(Display reading) 0.0

Ω

±0.8% of reading ±6 digits

Beeper sounds when<30

Ω

0.0

Ω

±0.8% of reading ±6 digits

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Non-Contact AC Voltage Detection

Range Resolution

0000 (signal strength) 1 count

Buzzer speeds up and red backlight flashes 1 count
when signal strength >0010

Non-Contact AC Current Detection

Range Resolution

0000 (signal strength) 1 count

Buzzer speeds up and green backlight flashes 1 count
when signal strength >0010

MAINTENANCE TIPS

The GT320 is not waterproof or water-resistant; avoid water, toxic
environments and temperature extremes.

Do not turn on the meter immediately after it has been taken from a
cold to a warm environment. The condensation that may result could
destroy the unit. Leave the meter switched off and wait until it reaches
room temperature.

Remove the battery when you do not expect to use the unit for a long
period of time (several months).

Clean the display by wiping it with a damp soft cloth. Never use
solvents or abrasives.

OPTIONAL ACCESSORIES AND
REPLACEMENT PARTS

• Replacement GTSF05 Wireless USB Receiver (dongle)

• Replacement RD330 Remote Display with Memory

• Replacement TL300 Fused Test Leads

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WARRANTY INFORMATION

General Tools & Instruments’ (General’s) GT320 Wireless Data Logging
Multimeter with Dot Matrix LCD plus NCVD/NCCD is warranted to the
original purchaser to be free from defects in material and
workmanship for a period of one year. Subject to certain restrictions,
General will repair or replace this product if, after examination, the
company determines it to be defective in material or workmanship.

This warranty does not apply to damages that General determines to
be from an attempted repair by non-authorized personnel or misuse,
alterations, normal wear and tear, or accidental damage. The defective
unit must be returned to General Tools & Instruments or to a General­authorized service center, freight prepaid and insured.

Acceptance of the exclusive repair and replacement remedies
described herein is a condition of the contract for purchase of this
product. In no event shall General be liable for any incidental, special,
consequential or punitive damages, or for any cost, attorneys’ fees,
expenses, or losses alleged to be a consequence of any damage due
to failure of, or defect in any product including, but not limited to, any
claims for loss of profits.

RETURN FOR REPAIR POLICY

Every effort has been made to provide you with a reliable product of
superior quality. However, in the event your instrument requires repair,
please contact our Customer Service to obtain an RGA (Return Goods
Authorization) number before forwarding the unit via prepaid freight to
the attention of our Service Center at this address:

General Tools & Instruments
80 White Street
New York, NY 10013
212-431-6100

23

GENERAL TOOLS & INSTRUMENTS

80 White Street

New York, NY 10013-3567

PHONE [phone]

FAX [phone]

TOLL FREE [phone]

e-mail: [e-mail]

www.generaltools.com

GT320 User’s Manual

Specifications subject to change without notice

©2012 GENERAL TOOLS & INSTRUMENTS

NOTICE - WE ARE NOT RESPONSIBLE FOR TYPOGRAPHICAL ERRORS.

MAN#GT320 7/12/12