Radio Shack 22-168A User manual

: MANUAL DUAL-DISPLAY
OWNER’S MANUAL DIGITAL MULTIMETER
w/PC Interface
Please read before using this equipment.
Cat. No. 22- 168A,
8 zy, =< y)
Sy a £———
(U1) Radio Shaek
"Ste

INTRODUCTION
Your Radio Shack LCD Digital Multimeter is a
portable, 3% digit, compact test instrument ideally
Suited for use in the field, lab, shop, and home.
Here are some of the professional features of
your new digital meter.
Computer Interface and Software — includes
both MS-DOS and Microsoft Windows software
-to let you interface the meter with your PC-com-
patible computer to log and graph measure-
ments.
Memory Recording — stores ten measure-
ments which you can download to a computer.
Frequency Check Function — measures fre-
quencies up to 20 MHz.
Transistor-Check Function — measures the
gain (hFE) of small-signal, bipolar transistors.
Capacitor-Check Function — measures the
capacitance of low-voltage capacitors.
Dual-Measurement Function — shows both
the AC voltage and frequency for AC measure-
ments or the logic level and ripple frequency for
logic measurements.
Analog Bargraph Display — indicates the mag-
nitude of the input compared to the full-scale
value of the measurement range.
MAX/MIN Hold Function — displays the maxi-
mum or minimum measured value on the second-
ary display.
Data Hold Function — freezes the secondary
display so you can keep the measured value
there even after you disconnect the probes.
Relative Offset — stores a value in memory and
displays the difference between the stored value
and subsequent readings.
© 1994 Tandy Corporation.
‘All Rights Reserved.
Radio Shack is a registered trademark used by Tandy Corporation.
2 Windows Is a trademark and MS-DOS Is a registered trademark of Microsoft Corporation.

Continuity Function — makes it easy to check
fuses, alarm wiring, cables, and connections.
Auto-Polarity Operation — protects ‘your meter
and gives valid measurements when you connect
the leads in reverse polarity.
Diode-Check Function — safely checks semi-
conductor junctions for open, short, or normal.
Combined (Function and Range) Selector
Switch — makes the meter easy to use.
Latest IC and Display Technology — ensures
reliability, accuracy, stability, and ease of opera-
tion.
Auto Power Shut-Off — tums off after 10 min-
utes of non-use to help conserve battery power.
Beeper — sounds tones for overload warming,
continuity function, and range selection.
Logic Test Function — checks logic levels
without extra logic probes.
Overload and Transient Protection — helps
protect the meter from accidental overload on
most ranges.
Low-Battery Indicator — appears when you
need to replace the batteries.
UL Listed — passes the stringent tests required
by Underwriters Laboratories for safety.
Cautions:
© Completely read this manual before you use
the meter.
¢ If you are not familiar with meters and testing
procedures, we suggest you read “Using
Your Meter” (Radio Shack Cat. No. 62-2039).

CONTENTS
A Word About Safety oo.
Specifications %
Special Panel Markings .
Preparation ......
Installing/Replacing the Battery
Using the Test Probes
Using the Stand...
Propping Up the Meter
Hanging the Meter
Pre-Operation Check
Making Measurements
Understanding Phantom Readings |
Measuring High-Voltage Circuits
AC/DC Voltage Measurement ..... ¥
Measuring an AC Voltage on a DC Bias 5
Measuring 3-Phase AC Voltages ..
Measuring AC/DC Current
Measuring Capacitance
Measuring Resistance
Checking Diodes
Checking Continuity

Checking Transistors.
Measuring Frequency.
Logic Test.
Using the Advanced Functions
Using the Auto-Hold Feature
Using the Data Hold Feature
Using the Minimum Feature
Using the Maximum Feature
Using the Relative Measurement Feature
Using the Communication Feature.......
Storing Measurements in Memory .
Recalling Stored Measurements
Using the Comparison Measurement Feature
Using the Dual Measurements Feature........
Using the Meter with a Computer-.......
Interfacing the Meter with a Compute:
Using the Supplied Software
Technical Information........
Communication Parameters
Data Format............0.00
Hints for Writing Your Own Software.
Replacing the Fuse............0::0ccse
Care and maintenance
FCC Statement.......

A WORD ABOUT SAFETY
This meter has been manufactured and tested
in accordance with IEC 348 and DINS7411/VDE
0411 Part 1 : Safety Requirements for Electronic
Measuring Apparatus, Safety Class II.
We have taken every precaution in designing and
manufacturing this meter to ensure that it is as
safe as we can make it. But safe operation de-
pends on you, the operator. We recommend that
you follow these simple safety rules:
Never apply voltages to the meter that exceed
the limits given in the specifications. Never
apply more than 1000 V DC or 750 V AC bet-
ween any terminals or between any input jack
and ground.
© Use extreme caution when working with volt-
ages above 30 V AC or 60 V DC. Always dis-
connect power from the circuit you are mea-
suring before you connect the test probes to
high-voltage points.
e Never connect the test probes to a source
of voltage when you select diode, resistance,
continuity, current measurement, capacitance,
or hFE functions.
© Always tum off the meter’s power and
disconnect the test probes before you replace
the battery or fuse.
© Never operate the meter unless the back cov-
er is in place and fully closed.
¢ Because some AC/DC sets have a hot chas-
sis, be sure the top of your work bench and
the floor undemeath it are made of noncon-
ductive materials.
The meter is fully calibrated and tested. Under
normal use, no further adjustment should be ne-
cessary. If the meter should require repair, do
not try to adjust it yourself. Take it to your local
Radio Shack store. Service by unauthorized per-
sonnel voids the warranty.

WARNING: USE EXTREME CAUTION IN THE
USE OF THIS DEVICE. IMPROPER USE OF
THIS DEVICE CAN RESULT IN INJURY OR
DEATH. FOLLOW ALL SAFEGUARDS SUG-
GESTED IN THIS OWNER’S MANUAL IN ADDI-
TION TO NORMAL SAFETY PRECAUTIONS IN
DEALING WITH ELECTRICAL CIRCUITS. DO
NOT USE THIS DEVICE IF YOU ARE UNFA-
MILIAR WITH ELECTRICAL CIRCUITS AND
TESTING PROCEDURES.
NOT FOR COMMERCIAL OR INDUSTRIAL
USE.

SPECIFICATIONS
DC VOLTS (Maximum Measuremen
200 mV - 2 - 20- 200 - 1000V .....
= 1000V)
auaantbdasasiis -- + 0.8% of Reading and
+ 0.3% of Full Scale
+1 in Last Digit
AC VOLTS (Maximum Measurement = 750 V)
200 mV - 2- 20-200V . aejainnisses -- + 1.2% of Reading and
+ 0.8% of Full Scale
+3 in Last Digit
TSO N ittcitesisisinssantivartictns ta aieaebiskacinineniaiiacanitiinsiabicuinsndiinttiienstutcn te TOI65OF ROAGING ANd
+ 1.2% of Full Scale
+3 in Last Digit
DC CURRENT vena Measurement = ae
200
uA-2mA
.
sada
ssrnanssaniennsieunarunannannemennenenanae
1.0%
of
Reading
and
+0.5% of Full Scale
+1 in Last Digit
+1.5% of Reading and
+ 1.2% of Full Scale
+1 in Last Digit
Q0A ores puna gunner setiineinnnnnnes + 2.5% Of Reading and
+ 2.0% of Full Scale
+5 in Last Digit
20 MA ~ 200 MA essssssssssssssssesesnnssennnseeee

RE
AC CURRENT (Maximum Measurement = 20 A)
200 uA-2mA....... + 1.5% of Reading and
+ 1.0% of Full Scale
+3 in Last Digit
20 mA- 200 mA .. + 2.3% of Reading and
+ 1.8% of Full Scale
+5 in Last Digit
20A... .. +3,.5% of Reading and
+3.0% of Full Scale
+7 in Last Digit
CAPACITANCE
200 pF - 200 nF ........ .. + 2.5% of Reading and
+ 2.0% of Full Scale
+3 in Last Digit
20 uF - 200 HF ...... .. £ 4.5% of Reading and
+4.0% of Full Scale
+5 in Last Digit
RESISTANCE
200 Ohm. ....... sue £1% Of Reading and
+ 0.5% of Full Scale
+3 in Last Digit

2 koh - 20k - 200K = 2 MOWM «.-sssressssseesseeseen
1% of Reading and
+0.5% of Full Scale
+1 in Last Digit
QO MOB on ssccssesssssessesessee .. £ 1.5% of Reading. and
+ 1.0% of Full Scale
+2 in Last Digit
2000 MOh .....scsscssssssssessseseeee .. + 5.5% of Reading and
+ 5.0% of Full Scale
+5 in Last Digit
FREQUENCY
QHZ = ZO MZ ansscssssssseesensinennosesessseteon + 2.5% of Reading and
+ 2.0% of Full Scale
+3 in Last Digit
DIODE CHECK FUNCTION ...................... For checking semiconductors for open, short, or normal
CONTINUITY TEST . Continuity buzzer sounds at less than 40 ohms
FE MEASUREMENT ........00.....cccesccssssseessns O-1000 HFE values for either PNP or NPN transistor.
Base DC Current about 10 yA
Vce about 3.0V
10