Agilent Technologies Electronic Accessory U1251A User Manual
Agilent U1251A and  
U1252A  
Handheld Digital  
Multimeter  
User’s and Service Guide  
Agilent Technologies  
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Safety Symbols  
The following symbols on the instrument and in the documentation indicate precautions which must be taken to  
maintain safe operation of the instrument.  
CAT IV  
600 V  
CAT III  
1000 V  
Category III 1000 V overvoltage protection  
Category IV 600 V overvoltage protection  
Earth (ground) terminal  
Equipment protected throughout by  
double insulation or reinforced  
insulation  
Caution, risk of danger (refer to this manual  
for specific Warning or Caution information)  
Caution, risk of electric shock  
Agilent U1251A/U1252A User’s and Service Guide  
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Safety Information  
This meter is safety-certified in compliance with EN/IEC 61010-1:2001, UL 61010-1 Second Edition and CAN/CSA  
22.2 61010-1 Second Edition, CAT III 1000 V/ CAT IV 600 V Overvoltage Protection, Pollution Degree II. Use with  
standard or compatible test probes.  
General Safety Information  
The following general safety precautions must be observed during all phases of operation, service, and repair of  
this instrument. Failure to comply with these precautions or with specific warnings elsewhere in this manual  
violates safety standards of design, manufacture, and intended use of the instrument. Agilent Technologies  
assumes no liability for the customer’s failure to comply with these requirements.  
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• When working above 70 VDC, 33 VAC RMS or 46.7 V peak, exercise caution – such  
range pose a shock hazard.  
WARNING  
• Do not measure more than the rated voltage (as marked on the meter) between  
terminals, or between terminal and earth ground.  
• Double-check the meter’s operation by measuring a known voltage.  
• For current measurement, turn off circuit power before connecting the meter to the  
circuit. Always place the meter in series with the circuit.  
• When connecting probes, always connect the common test probe first. When  
disconnecting probes, always disconnect the live test probe first.  
• Detach test probes from the meter before you open the battery cover.  
• Do not use the meter with the battery cover or part of the cover removed or loose.  
• Replace the battery as soon as the low battery indicator  
flashes on screen. This is  
to avoid false readings, which may lead to possible electric shock or personal injury.  
• Do not operate the product in an explosive atmosphere or in the presence of  
flammable gases or fumes.  
• Inspect the case for cracks or missing plastic. Pay extra attention to the insulation  
surrounding the connectors. Do not use the meter if it is damaged.  
• Inspect the test probes for damaged insulation or exposed metal, and check for  
continuity. Do not use the test probe if it is damaged.  
• Do not use any other AC charger adaptor apart from the one certified by Agilent with  
this product.  
• Do not use repaired fuses or short-circuited fuse-holders. For continued protection  
against fire, replace the line fuses only with fuses of the same voltage and current  
rating and recommended type.  
• Do not service or perform adjustments alone. Under certain condition, hazardous  
voltages may exist, even with the equipment switched off. To avoid dangerous electric  
shock, service personnel must not attempt internal service or adjustment unless  
another person, capable of rendering resuscitation or first aid, is present.  
• Do not substitute parts or modify equipment to avoid the danger of introducing  
additional hazards. Return the product to Agilent Technologies Sales and Service  
Office for service and repair to ensure the safety features are maintained.  
• Do not operate damaged equipment as the safety protection features built into this  
product may have been impaired, either through physical damage, excessive  
moisture, or any other reason. Remove power and do not use the product until safe  
operation can be verified by service-trained personnel. If necessary, return the  
product to Agilent Technologies Sales and Service Office for service and repair to  
ensure the safety features are maintained.  
Agilent U1251A/U1252A User’s and Service Guide  
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• Turn off the circuit power and discharge all high-voltage capacitors in the circuit before  
you perform resistance, continuity, diodes, or capacitance tests.  
• Use the correct terminals, function, and range for your measurements.  
• Never measure voltage when current measurement is selected.  
• Use only recommended rechargeable battery. Ensure proper insertion of battery in the  
meter, and follow the correct polarity.  
CAUTION  
• Disconnect test leads from all the terminals during battery charging.  
VI  
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Regulatory Markings  
The C-tick mark is a registered  
trademark of the Spectrum  
The CE mark is a registered trademark  
of the European Community. This CE  
mark shows that the product complies  
with all the relevant European Legal  
Directives.  
Management Agency of Australia. This  
signifies compliance with  
the Australia EMC Framework  
regulations under the terms of the  
Radio Communication Act of 1992.  
This instrument complies with the  
WEEE Directive (2002/96/EC) marking  
requirement. This affixed product label  
indicates that you must not discard  
this electrical/electronic product in  
domestic household waste.  
ICES/NMB-001 indicates that this ISM  
device complies with the Canadian  
ICES-001.  
Cet appareil ISM est confomre a la  
norme NMB-001 du Canada.  
The CSA mark is a registered  
trademark of the Canadian Standards  
Association.  
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Waste Electrical and Electronic Equipment (WEEE) Directive  
2002/96/EC  
This instrument complies with the WEEE Directive (2002/96/EC) marking  
requirement. This affixed product label indicates that you must not discard  
this electrical/electronic product in domestic household waste.  
Product Category:  
With reference to the equipment types in the WEEE directive Annex 1, this  
instrument is classified as a “Monitoring and Control Instrument” product.  
The affixed product label is as shown below.  
Do not dispose in domestic household waste  
To return this unwanted instrument, contact your nearest Agilent  
Technologies, or visit: www.agilent.com/environment/product for more  
information.  
Agilent Technologies, through Rechargeable Battery Recycling Corporation (RBRC), offers free and convenient  
battery recycling options in the U.S. and Canada. Contact RBRC at 877-2-RECYCLE (877.273.2925) or online at:  
http://www.call2recycle.org/ for the nearest recycling location.  
VIII  
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In This Guide…  
1
Getting Started  
This chapter contains information on the Agilent U1251A and U1252A  
handheld multimeter front panel, rotary switch, keypad, display, terminals  
and rear panel.  
2
3
4
5
Making Measurements  
This chapter contains information on how to make measurements using  
the U1251A and U1252A handheld digital multimeter.  
Functions and Features  
This chapter contains information on the functions and features that are  
available for the U1251A and U1252A digital multimeter.  
Changing The Default Setting  
This chapter shows you how to change the default factory settings of the  
U1251A and U1252A and other available setting options  
Maintenance  
This chapter will go through how to troubleshoot the handheld digital  
multimeter if any problems arise.  
6
7
Performance Tests and Calibration  
This chapter contains the performance test and the adjustment procedure.  
Specifications  
This chapter lists the product characteristics, specification assumptions  
and the specifications of the U1251A and U1252A digital multimeters.  
Agilent U1251A/U1252A User’s and Service Guide  
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Declaration of Conformity (DoC)  
The Declaration of Conformity (DoC) for this instrument is available on the  
Web site. You can search the DoC by its product model or description.  
http://regulations.corporate.agilent.com/DoC/search.htm  
NOTE  
If you are unable to search for the respective DoC, please contact your  
local Agilent representative.  
X
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Contents  
1
Getting Started  
Introducing the U12521A/U1252A Handheld Digital Multimeter  
2
Check the shipment  
3
Adjusting the tilt-stand  
4
The rear panel at a glance  
The keypad at a glance  
7
9
The display at a glance 11  
Selecting display with the Hz button 16  
Selecting display with the Dual button 18  
Selection display with the Shift button 20  
The terminals at a glance 22  
2
Making Measurements  
Understanding The Measurement Instructions 24  
Measuring Voltage 24  
Measuring AC voltage 25  
Measuring DC voltage 26  
Measuring Current 27  
µA & mA measurement 27  
Percentage scale of 4 mA to 20 mA 29  
A (ampere) measurement 31  
Frequency Counter 32  
Measuring Resistance, Conductance and Testing Continuity 34  
Testing Diodes 38  
Measuring Capacitance 41  
Measuring Temperature 43  
Alerts and Warning During Measurement 47  
Abbreviated Book Title Variable (Edit this)  
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Overload alert 47  
Input warning 47  
Charge terminal alert 48  
3
Functions and Features  
Dynamic Recording 50  
Data Hold (Trigger Hold) 52  
Refresh Hold 53  
Null (Relative) 55  
Decibel Display 57  
1 ms Peak Hold 59  
Data Logging 61  
Manual logging 61  
Interval logging 63  
Reviewing logged data 65  
Square Wave Output (for U1252A) 67  
Remote Communication 71  
4
Changing The Default Setting  
Selecting Setup Mode 74  
Setting Data Hold/Refresh Hold Mode 77  
Setting Data Logging Mode 78  
Setting Thermocouple Types (U1252A only) 79  
Setting Reference Impedance for dBm Measurement 80  
Setting Minimum Frequency Measurement 81  
Setting Temperature Unit 82  
Setting Auto Power Saving Mode 84  
Setting Percentage (%) Scale Readout 86  
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Setting Beep Frequency 87  
Setting Backlight Timer 88  
Setting Baud Rate 89  
Setting Parity Check 90  
Setting Data Bit 91  
Setting Echo Mode 92  
Setting Print Mode 93  
Returning to Default Factory Settings 94  
5
Maintenance  
Introduction 96  
General maintenance 96  
Battery replacement 96  
Storage considerations 98  
Charging the battery 98  
Fuse checking procedure 105  
Replacing the fuse 106  
Troubleshooting 108  
Replaceable Parts 109  
To order replaceable parts 109  
6
Performance Tests and Calibration  
Calibration Overview 112  
Closed-case electronic calibration 112  
Agilent Technologies calibration services 112  
Calibration interval 113  
Adjustment is recommended 113  
Recommended Test Equipment 114  
Basic Operating Test 115  
Backlit test 115  
Abbreviated Book Title Variable (Edit this)  
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Testing the display 115  
Current terminal test 116  
Charge terminal alert test 117  
Test Considerations 118  
Calibration Security 119  
Performance Verification Tests 120  
Unsecuring the instrument for calibration 128  
Calibration process 131  
Using the front panel for adjustments 132  
Adjustments Consideration 133  
Valid adjustment input values 134  
Adjustment procedure 135  
Finishing the adjustment 142  
To read the calibration count 142  
Calibration errors 143  
7
Specifications  
Product Characteristics 146  
Measurement Category 149  
Measurement category definition 149  
Specification Assumptions 150  
Electrical Specifications 151  
DC Specifications 151  
AC Specifications 153  
AC+DC Specifications for U1252A 155  
Capacitance Specifications 156  
Temperature Specifications 156  
Frequency Specifications 157  
Duty Cycle and Pulse Width Specifications 157  
Frequency Sensitivity Specifications 158  
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Peak Hold Specifications 159  
Frequency Counter Specifications for U1252A 160  
Square Wave Output for U1252A 161  
Operating Specifications 162  
Display update rate (approximate) 162  
Input impedance 163  
Abbreviated Book Title Variable (Edit this)  
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XVIII  
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List of Figures  
Figure 1-1 Tilt-stand at 60°  
Figure 1-2 Tilt-stand at 30°  
4
4
Figure 1-3 Tilt-stand at hanging position  
Figure 1-4 U1252A front panel  
Figure 1-5 Rear panel  
5
6
7
Figure 1-6 Rotary switch  
Figure 1-7 U1252A keypad  
8
9
Figure 1-8 Display symbols 11  
Figure 1-9 U1252A connector terminals 22  
Figure 2-1 Measuring AC voltage 25  
Figure 2-2 Measuring DC voltage 26  
Figure 2-3 Measuring mA and mA current 28  
Figure 2-4 Measuring scale of 4-20 mA 30  
Figure 2-5 A (ampere) current measurement 31  
Figure 2-6 Measuring frequency 33  
Figure 2-7 Measuring resistance 34  
Figure 2-8 Audible continuity, conductance, and resistance  
test. 35  
Figure 2-9 Conductance measurement 37  
Figure 2-10 Measuring forward bias of diode 39  
Figure 2-11 Measuring reverse bias of diode 40  
Figure 2-12 Capacitance measurements 42  
Figure 2-13 Connecting the thermal probe into the non-compensa-  
tion transfer adapter 44  
Figure 2-14 Connecting the probe with adapter into the  
multimeter 44  
Figure 2-15 Surface temperature measurement 46  
Figure 2-16 Input terminal warning 47  
Figure 2-17 Charge terminal alert 48  
Figure 3-1 Dynamic recording mode operation 51  
Figure 3-2 Data hold mode operation 52  
Figure 3-3 Refresh hold mode operation 54  
Figure 3-4 Null (relative) mode operation 56  
Figure 3-5 dBm/dBV display mode operation 58  
Figure 3-6 1 ms peak hold mode operation 60  
Figure 3-7 Hand (Manual) logging mode operation 62  
Abbreviated Book Title Variable (Edit this)  
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Figure 3-8 Full Log 62  
Figure 3-9 Interval (Automatic) logging mode operation 64  
Figure 3-10 Log review mode operation 66  
Figure 3-11 Frequency adjustment for square wave output 68  
Figure 3-12 Pulse width adjustment for square wave output 69  
Figure 3-13 Duty cycle adjustment for Square Wave 70  
Figure 3-14 Cable connection for remote communication 71  
Figure 4-1 Data hold/Refersh hold setup 77  
Figure 4-2 Data logging setup 78  
Figure 4-3 Thermocouple type setup 79  
Figure 4-4 Reference impedance for dBm measurement setup 80  
Figure 4-5 Minimum frequency setup 81  
Figure 4-6 Temperature unit setup 83  
Figure 4-7 Auto power saving setup 85  
Figure 4-8  
% scale readout setup 86  
Figure 4-9 Beep frequency setup 87  
Figure 4-10 Backlit timer setup 88  
Figure 4-11 Baud rate setup remote control 89  
Figure 4-12 Parity check setup 90  
Figure 4-13 Data bit setup for remote control 91  
Figure 4-14 Echo mode setup for remote control 92  
Figure 4-15 Print mode setup for remote control 93  
Figure 4-16 Reset setup 94  
Figure 5-1 9 V rectangular battery 97  
Figure 5-2 Battery capacity display as trickle 100  
Figure 5-3 Self-test 100  
Figure 5-4 Charging mode 102  
Figure 5-5 Charge end and trickle state 103  
Figure 5-6 Battery charging procedure 104  
Figure 5-7 Fuse replacement 107  
Figure 6-1 LCD display 115  
Figure 6-2 Input warning 116  
Figure 6-3 Charge terminal alert 117  
X
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II  
List of Tables  
Table 1-1 Rotary switch description and functions  
8
Table 1-2 Keypad desciption and functions  
Table 1-3 General display symbols 12  
Table 1-4 Priamry display symbols 13  
Table 1-5 Secondary display symbols 14  
Table 1-6 Analog bar range and counts 15  
9
Table 1-7 Selecting display with the Hz button 16  
Table 1-8 Selecting display with the Dual button 18  
Table 1-9 Selecting display with the Shift button 20  
Table 1-10 Terminal connections for different measuring  
functions 22  
Table 2-1 Numerical steps descriptions 24  
Table 2-2 Percentage scale and measurement range 29  
Table 2-3 Audible continuity measurement range 36  
Table 4-1 Available setting options in Setup mode 75  
Table 5-1 Battery voltage and corresponding percentage of charg-  
es in standby and charging modes 100  
Table 5-2 Error messages 101  
Table 5-3 Measurement readings for fuse checking 106  
Table 5-4 Fuse specifications 107  
Table 5-5 Basic troubleshooting procedures 108  
Table 6-1 Recommended Test Equipment 114  
Table 6-2 Performance verification test steps 121  
Table 6-3 Valid adjustment input values 134  
Table 6-4 Adjustment table 137  
Table 7-1 DC Accuracy (% of reading + Number of Least Signifi-  
cant Digit) 151  
Table 7-2 U1251A accuracy specifications (% of reading + num-  
ber of LSD) for true RMS AC voltage 153  
Table 7-3 U1251A accuracy specifications (% of reading + num-  
ber of LSD) for true RMS AC current 153  
Table 7-4 U1252A accuracy specifications (% of reading + num-  
ber of LSD) for true RMS AC voltage 154  
Table 7-5 U1252A accuracy specifications (% of reading + num-  
ber of LSD) for true RMS AC current 154  
Table 7-6 U1252A true RMS ac+dc voltage specifications 155  
Abbreviated Book Title Variable (Edit this)  
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Table 7-7 U1252A true RMS ac+dc current specifications 155  
Table 7-8 Capacitance specifications 156  
Table 7-9 Temperature specifications 156  
Table 7-10 Frequency specifications 157  
Table 7-11 Duty cycle and pulse width specifications 157  
Table 7-12 Frequency sensitivity and trigger level specifications for  
voltage measurements 158  
Table 7-13 Frequency sensitivity specifications for current  
measurements 159  
Table 7-14 Peak hold specifications for dc voltage and current  
measurements 159  
Table 7-15 Frequency counter (divide by 1) specifications 160  
Table 7-16 Frequency counter (divide by 100 [4])  
specifications 160  
Table 7-17 Square wave output specifications 161  
Table 7-18 Display update rate (approximate) 162  
Table 7-19 Input Impedance 163  
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Agilent U1251A and U1252A Handheld Digital Multimeter  
User’s and Service Guide  
1
Getting Started  
Introducing the U12521A/U1252A Handheld Digital Multimeter  
2
Check the shipment  
3
Adjusting the tilt-stand  
4
The front panel at a glance  
The rear panel at a glance  
6
7
The rotary switch at a glance  
The keypad at a glance  
The display at a glance 11  
8
9
Selecting display with the Hz button 16  
Selecting display with the Dual button 18  
Selection display with the Shift button 20  
The terminals at a glance 22  
This chapter contains information on the Agilent U1251A  
and U1252A handheld multimeter front panel, rotary switch,  
keypad, display, terminals and rear panel.  
Agilent Technologies  
1
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1
Getting Started Tutorial  
Introducing the U12521A/U1252A Handheld Digital Multimeter  
Key features of this digital multimeter:  
• DC, AC, and AC + DC (U1252A only) voltage and current  
measurements.  
• True-RMS measurement for both AC voltage and current  
• Rechargeable Ni-MH battery with built-in charging  
capability (U1252A only)  
• Ambient temperature on second display  
• Battery capacity indicator  
• Blue LED backlight  
• Resistance measurement of up to 50 MΩ (for U1251A)  
and 500 MΩ (for U1252A)  
• Conductance measurement from 0.01 nS (100 GΩ) ~ 50 nS  
• Capacitance measurement of up to 100 mF  
• Frequency counter up of to 20 MHz (U1252A only)  
•
The % scale readout for 4–20 mA or 0–20 mA measurement  
• dBm with selectable reference impedance  
• 1 ms Peak Hold to catch inrush voltage and current easily  
• Temperature test with selectable 0 °C compensation  
(without ambient temperature compensation).  
• K-type (for U1251A) and J/K-types temperature  
measurement (for U1252A)  
• Frequency, duty cycle, and pulse width measurements  
• Dynamic Recording for min, max, and average readings  
• Data Hold with manual or auto trigger and Null mode  
• Diode and audible continuity tests  
• Square wave generator with selectable frequency, pulse  
width and duty cycle (U1252A only)  
• Agilent GUI Application Software (IR-USB cable sold  
separately)  
• Closed case calibration  
2
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Getting Started Tutorial  
1
Check the shipment  
Verify that you have received the following items with your  
multimeter:  
• 9 V alkaline battery (for U1251A only)  
• Soft carrying case  
• 4 mm probes  
• Test leads  
• Alligator clips  
• SMT grabbers  
• Fine tips test probes  
• Mini grabber (black only)  
• Rechargeable 7.2 V battery (for U1252A only)  
• Power cord & AC adapter (for U1252A only)  
• Quick Start Guide  
• CD containing the User’s Guide, application software and  
instrument drivers  
• Certificate of Calibration  
Contact your nearest Agilent Sales Office if any of the above  
are missing.  
Inspect the shipping containing for damage. Signs of damage  
may include a dented or torn shipping container or  
cushioning material that indicates signs of unusual stress or  
compacting. Save the packaging material in case the  
multimeter needs to be returned.  
Please refer to the Agilent Handheld Tools brochure  
(5989-7340EN) for the full and latest list of handheld  
accessories available.  
Agilent U1251A/U1252A User’s and Service Guide  
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1
Getting Started Tutorial  
Adjusting the tilt-stand  
To adjust the meter to a 60° standing position, pull the  
tilt-stand outwards to its maximum reach.  
IR-USB cable  
To PC (host)  
Tilt-stand at 60 °  
Figure 1-1 Tilt-stand at 60°  
To adjust the meter to a 30° standing position, bend the tip  
of the stand so that it is parallel to the ground before  
pulling the stand outwards to its maximum reach.  
IR-USB cable  
To PC (host)  
Tilt-stand at 30 °  
Figure 1-2 Tilt-stand at 30°  
4
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Getting Started Tutorial  
1
To adjust the meter to a hanging position follow the steps  
shown in Figure 1-3 below.  
2. Detach the tilt-stand  
maximum reach  
1. Extend the tilt-stand until its  
4. Re-attach the tilt-stand to an  
upright position  
this side of the  
3. Flip the tilt-stand over until  
facing you.  
stand is facing the device instead of  
Figure 1-3 Tilt-stand at hanging position  
Agilent U1251A/U1252A User’s and Service Guide  
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1
Getting Started Tutorial  
The front panel at a glance  
Display  
Keypad  
Rotary switch  
Terminal  
Connectors  
Figure 1-4 U1252A front panel  
6
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Getting Started Tutorial  
1
The rear panel at a glance  
IR communication port  
Test probe  
holders  
Tilt-stand  
Battery access  
cover  
Figure 1-5 Rear panel  
Agilent U1251A/U1252A User’s and Service Guide  
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1
Getting Started Tutorial  
The rotary switch at a glance  
6
7
8
5
4
3
2
9
10  
1
Figure 1-6 Rotary switch  
Table 1-1 Rotary switch description and functions  
No.  
1
Description/Function  
Charge mode (U1252A only) or OFF  
2
AC voltage  
3
AC voltage, DC voltage or DC+AC voltage (U1252A only)  
DC mV, AC mV, AC+DC mV (U1252A only)  
Resistance (Ω), Continuity, and Conductance ( nS )  
Frequency counter (U1252A only) or Diode  
Capacitance or Temperature  
4
5
6
7
8
DC µA, AC µA, and AC+DC µA  
9
DC mA, DC current, AC mA, AC current, or AC+DC current  
10  
Square-wave output, Duty cycle, or Pulse width output (for  
U1252A) and OFF (for U1251A)  
8
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Getting Started Tutorial  
1
The keypad at a glance  
The operation of each key is shown below. Pressing a key  
illuminates a related symbol on the display and emits a beep  
from the multimeter. Turning the rotary switch to another  
position resets the current operation of the key.  
Figure 1-7 below shows the keypad of the U1252A. The ms%  
(Pulse width/Duty cycle),  
Hz  
, and frequency counter  
functions are only available on the U1252A.  
4
3
5
2
1
6
7
Figure 1-7 U1252A keypad  
Table 1-2 Keypad desciption and functions  
Button Function when pressed for less than 1 second  
Function when pressed for more than 1 second  
1
acts as a toggle switch to turn backlit ON/OFF.  
displays the battery capacity for 3 seconds.  
Backlit automatically turns off after 30s (default) [1]  
.
2
freezes the measured value. In Data Hold  
enters Dynamic Recording mode. Press  
mode, press again to trigger hold of the next measured again to scroll through Max, Min, Avg, and present  
value. In Refresh Hold mode, reading updates  
readings (indicated by MAXMINAVG on display).  
automatically once reading is stable and count setting  
is exceeded [1]  
.
3
saves displayed value as a reference to be  
subtracted from subsequent measurements. Press  
again to see the relative value that has been saved.  
enters 1 ms Peak Hold mode. Press  
to scroll through Max and Min peak readings.  
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Button  
Function when pressed for less than 1 second  
Function when pressed for more than 1 second  
4
scrolls through the measuring function(s) at a  
particular rotary switch position.  
enters Log Review mode. Press  
switch to manual or interval logging data. Press  
to  
or  
to view first or last logged data respectively.  
Press  
or  
to scroll up or down logged data.  
Press  
for more than 1 second to exit mode.  
5
6
scrolls through available measuring ranges  
sets to Auto Range mode.  
(except when rotary switch is set at TEMP or at Hz [for  
U1252A] position) [2]  
.
scrolls through available dual-combination  
exits Hold, Null, Dynamic Recording, 1 ms  
displays (except when rotary switch is set at TEMP, Hz Peak Hold and dual display modes.  
or [for U1252A] position, or when meter is in  
1 ms peak hold or dynamic recording mode) [3]  
.
7
enters Frequency Test mode for current or  
voltage measurements. Press to scrogh press  
enters logging mode. In manual data logging,  
to log data manually into memory. In  
frequency (Hz), duty cycle (%) and pulse width (ms)  
functions. In duty cycle (%) and pulse width (ms)  
automatic data logging, data logs automatically [1]  
.
Press  
for more than 1 second to exit auto data  
tests, press  
pulse.  
to switch to positive or negative logging mode.  
Notes for keypad descriptions and functions:  
1
See Table 4-1 on page 75, “Available setting options in Setup mode,” for details of available options.  
2
3
When rotary switch is at TEMP, press  
switch to division of signal frequency by 1 or 100.  
When rotary switch is at TEMP, ETC is ON by default. You may press  
to switch to ºC or ºF display. When rotary switch is at Hz, press  
to  
to disable ETC (Environment Temperature  
Compensation),  
will appear on display. For pulse and duty cycle measurement, press  
to switch trigger slope  
to positive or negative. When meter is in peak or dynamic-recording mode, press  
dynamic recording mode.  
to restart 1 ms peak hold or  
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The display at a glance  
To view the full display (with all segments illuminated),  
press and hold the  
button while turning the rotary  
switch from OFF to any non-OFF position. After you have  
finished viewing the full display, press any button to resume  
normal functionality based on the rotary switch position.  
This is followed by a wake-up feature.  
The meter will then enter power save mode once auto power  
off (APF) is enabled. To wake the meter up:  
1 Turn the rotary switch to OFF position then ON again.  
2 Press any button for rotary switch position that is not at  
square wave output position. (U1252A only)  
3 To set the rotary switch at square wave out position,  
press only the Dual, Range and Hold buttons or turn the  
rotary switch to another position. (U1252A only)  
The LCD signs are explained in the following tables.  
Figure 1-8 Display symbols  
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Table 1-3 General display symbols  
LCD symbol  
Description  
Remote control  
Thermocouple types:  
Null math function  
(K-type) (J-type)  
NULL  
Diode / Audible continuity  
Audible continuity for resistance  
View mode for checking logged data  
Data logging indication  
Square wave output (U1252A only)  
•
•
•
•
Positive slope for pulse width (ms) and duty cycle (%) measurement  
Charging capacitor as capacitance measurement  
Negative slope for pulse width (ms) and duty cycle (%) measurement  
Discharging capacitor as capacitance measurement  
Low battery indication  
Auto power off enable  
Refresh (auto) Hold  
Trigger (manual) Hold  
TRIG  
MAXMINAVG  
MAX  
Dynamic Recording mode: Present value on primary display  
Dynamic Recording mode: Maximum value on primary display  
Dynamic Recording mode: Minimum value on primary display  
MIN  
AVG  
Dynamic Recording mode: Average value on primary display  
1 ms Peak Hold mode: Positive peak value on primary display  
1 ms Peak Hold mode: Negative peak value on primary display  
MAX  
MIN  
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The primary display signs are explained below.  
Table 1-4 Priamry display symbols  
LCD symbol  
Description  
Auto range  
AC + DC  
DC  
AC  
Polarity, digits, and decimal points for primary display  
dBm  
dBV  
MkHz  
MkΩ  
nS  
Decibel unit relative to 1 mW  
Decibel unit relative to 1 V  
Frequency units: Hz, kHz, MHz  
Resistance units: Ω, kΩ, MΩ  
Conductance unit  
mV  
Voltage units: mV, V  
µmA  
%
Current units: µA, mA, A  
Duty cycle measurement  
Pulse width unit  
ms  
µmnF  
ºC  
Capacitance units: nF, µF, mF  
Celsius temperature unit  
ºF  
Fahrenheit temperature unit  
Percentage scale readout proportional to DC 0–20 mA  
Percentage scale readout proportional to DC 4–20 mA  
%
%
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The secondary display signs are explained below.  
Table 1-5 Secondary display symbols  
LCD symbol  
Description  
AC + DC  
DC  
AC  
Polarity, digits and decimal points for secondary display  
Frequency units: Hz, kHz  
kHz  
No ambient temperature compensation, just thermocouple measurement  
Celsius ambient temperature unit  
ºC  
ºF  
Fahrenheit ambient temperature unit  
mV  
µmA  
s
Voltage units: mV, V  
Current units: µA, mA, A  
Elapsed time unit: s (second) for Dynamic Recording and 1 ms Peak Hold modes  
The analog bar emulates the needle on an analog multimeter,  
without displaying the overshoot. When measuring peak or  
null adjustments and viewing fast-changing inputs, the bar  
graph provides a useful indication because it has quicker  
update rate for fast response applications.  
The bar graph is not used for square wave output, frequency,  
duty cycle, pulse width, 4–20 mA% scale, 0–20 mA% scale  
and temperature measurements. When frequency, duty cycle,  
and pulse width are indicated on the primary display during  
voltage or current measurement, the bar graph represents  
the voltage or current value. When 4–20 mA% scale or  
0–20 mA% scale is indicated on the primary display, the bar  
graph represents the current value and not the percentage.  
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The “+” or “–” sign is indicated when the positive or  
negative value has been measured or calculated. Each  
segment represents 2500 or 500 counts depending on the  
range indicated on the peak bar graph. See the Table 1-6  
below.  
Table 1-6 Analog bar range and counts  
Range  
Counts/segments  
2500  
Used for the function  
V, Ω, Diode  
2500  
2500  
500  
V, A, Ω  
V, A, Ω, nS  
V,  
500  
500  
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Selecting display with the Hz button  
The frequency measurement feature helps to detect the  
presence of harmonic currents in neutral conductors and  
determines whether these neutral currents are the result of  
unbalanced phases or non-linear loads. Press  
to access  
the frequency measurement mode for current or voltage  
measurements — voltage or current on the secondary display  
and frequency on the primary display. Alternatively, pulse  
width (ms) or duty cycle (%) can appear on the primary  
display by pressing  
again. This enables the  
simultaneous monitoring of real-time voltage and current  
with frequency, duty cycle, or pulse width. Voltage or  
current resumes on primary display after you press and hold  
for more than 1 second.  
Table 1-7 Selecting display with the Hz button  
Rotary switch position (Function)  
Primary display  
Frequency (Hz)  
Pulse width (ms)  
Secondary display  
AC V  
for U1252A  
(AC voltage)  
Duty cycle (%)  
Frequency (Hz)  
Pulse width (ms)  
Duty cycle (%)  
DC V  
V for U1251A  
for U1252A  
(DC voltage)  
for U1252A  
Frequency (Hz)  
Pulse width (ms)  
Duty cycle (%)  
Frequency (Hz)  
Pulse width (ms)  
Duty cycle (%)  
Frequency (Hz)  
Pulse width (ms)  
Duty cycle (%)  
AC + DC V  
AC mV  
(AC + DC voltage)  
(AC voltage)  
(DC voltage)  
DC mV  
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Table 1-7 Selecting display with the Hz button (continued)  
Frequency (Hz)  
AC + DC mV  
Pulse width (ms)  
(AC + DC voltage)  
Duty cycle (%)  
[for U1252A]  
Frequency (Hz)  
Pulse width (ms)  
Duty cycle (%)  
Frequency (Hz)  
Pulse width (ms)  
Duty cycle (%)  
Frequency (Hz)  
Pulse width (ms)  
Duty cycle (%)  
AC µA  
DC µA  
(AC Current)  
(DC current)  
AC + DC µA  
(AC + DC current)  
[for U1252A]  
Frequency (Hz)  
Pulse width (ms)  
Duty cycle (%)  
Frequency (Hz)  
Pulse width (ms)  
Duty cycle (%)  
Frequency (Hz)  
Pulse width (ms)  
Duty cycle (%)  
AC mA or A  
DC mA or A  
(AC current)  
(DC current)  
AC + DC mA or A  
[for U1252A]  
(AC + DC current)  
Frequency (Hz)  
Pulse width (ms)  
Duty cycle (%)  
- 1 -  
Hz (Frequency counter) - press  
to select frequency division by 1 [for  
U1252A]  
Frequency (Hz)  
- 100 -  
Hz (Frequency counter) - press  
to select frequency division by 100 [for  
U1252A]  
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Selecting display with the Dual button  
Press  
to select different combinations of dual display.  
Normal single display resumes after you press and hold  
for more than 1 second. See Table 1-8 below.  
Table 1-8 Selecting display with the Dual button  
Rotary switch position (Function)  
Primary display  
Secondary display  
Hz (AC coupling)  
AC V  
AC V  
dBm or dBV (select  
(AC voltage)  
by pressing  
)
AC V  
AC V  
dBm or dBV [1]  
Ambient temperature °C or °F  
Hz (AC coupling)  
AC V  
for U1252A  
(AC voltage)  
AC V  
DC V  
AC V  
Ambient temperature °C or °F  
Hz (DC coupling)  
DC V  
DC V  
dBm or dBV [1]  
V for U1251A/  
for U1252A  
DC V  
AC V [for U1252A]  
Ambient temperature °C or °F  
Hz (AC coupling)  
AC + DC V  
(DC voltage)  
DC V  
AC + DC V  
dBm or dBV [1]  
AC + DC V  
AC + DC V  
AC + DC V  
AC mV  
for U1252A  
(AC + DC voltage)  
AC V  
DC V  
Ambient temperature °C or °F  
Hz (AC coupling)  
AC mV  
dBm or dBV [1]  
(AC voltage)  
(DC voltage)  
AC mV  
DC mV  
AC mV  
Ambient temperature °C or °F  
Hz (DC coupling)  
DC mV  
DC mV  
dBm or dBV [1]  
DC mV  
AC mV  
DC mV  
Ambient temperature °C or °F  
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Table 1-8 Selecting display with the Dual button  
AC + DC mV  
dBm or dBV  
AC + DC mV  
AC + DC mV  
AC + DC mV  
Hz (AC coupling)  
AC + DC mV  
(AC + DC voltage)  
AC mV  
DC mV  
Ambient temperature °C or °F  
Hz (DC coupling)  
DC μA  
DC μA  
DC μA  
AC μA  
AC μA  
AC μA  
(DC current)  
(AC current)  
Ambient temperature °C or °F  
Hz (AC coupling)  
DC μA  
AC μA  
Ambient temperature °C or °F  
Hz (AC coupling)  
AC + DC μA  
AC + DC μA  
AC + DC μA  
AC + DC μA  
DC mA  
AC μA  
DC μA  
(AC + DC current)  
[for U1252A]  
Ambient temperature °C or °F  
Hz (DC coupling)  
AC mA  
DC mA  
(DC current)  
% (0–20 or 4–20)  
DC mA  
DC mA  
Ambient temperature °C or °F  
Hz (AC coupling)  
DC mA  
AC mA  
AC mA  
(AC current)  
AC mA  
Ambient temperature °C or °F  
Hz (AC coupling)  
AC mA  
AC + DC mA  
AC + DC mA  
AC + DC mA  
AC + DC mA  
DC A  
(AC + DC current)  
[for U1252A]  
DC mA  
Ambient temperature °C or °F  
Hz (DC coupling)  
(DC current)  
(AC current)  
DC A  
DC A  
AC A  
AC A  
AC A  
AC A  
Ambient temperature °C or °F  
Hz (AC coupling)  
DC A  
Ambient temperature °C or °F  
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Table 1-8 Selecting display with the Dual button  
AC + DC A  
AC + DC A  
Hz (AC coupling)  
AC A  
(AC + DC current)  
[for U1252A]  
AC + DC A  
DC A  
AC + DC A  
Ambient temperature °C or °F  
Ambient temperature °C or °F  
nF / V / Ω / nS  
(Capacitance)  
(Diode)/  
Ω (Resistance)/  
nS (Conductance)  
TEMP (Temperature)  
°C (°F)  
°C (°F)  
Ambient temperature °C or °F  
Ambient temperature °C or °F /  
0 °C compensation (select by  
pressing  
)
Notes for selecting display with the Dual button:  
1 Reading of dBm or dBV depends on the last review on AC V. If the last review is in dBV, the following display  
will also remain in dBV.  
Selection display with the Shift button  
The table below shows selection of primary display, with  
respect to measuring function (rotary switch position), using  
the SHIFT button.  
Table 1-9 Selecting display with the Shift button  
Rotary switch position (Function)  
Primary display  
AC V  
dBm (in dual display mode) [1]  
dBV (in dual display mode) [1]  
DC V  
(AC Voltage)  
V for U1251A  
DC V  
AC V  
for U1252A  
(AC + DC Voltage)  
AC + DC V  
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Table 1-9 Selecting display with the Shift button  
DC mV  
AC mV  
for U1252A  
(AC + DC Voltage)  
AC + DC mV  
Ω
Ω
nS  
Ω
(Resistance)  
Diode  
Hz  
(Diode Test and Frequency)  
/ TEMP  
Capacitance  
Temperature  
(Capacitance and Temperature)  
DC μA  
AC μA  
AC + DC μA [for U1252A]  
(AC Current)  
DC mA  
AC mA  
AC + DC mA  
%(0–20 or 4–20)  
DC A  
(DC Current)  
AC A  
AC + DC A [for U1252A]  
(AC + DC Current)  
Duty cycle (%)  
Pulse width (ms)  
(Square wave output for U1252A)  
Notes for selecting display with the Shift button:  
1 Press  
to switch between dBm and dBV measurement.  
Press  
for more than 1 second to return to AC V measurement only.  
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The terminals at a glance  
To avoid damaging the multimeter, do not exceed the input limit.  
WARNING  
Figure 1-9 U1252A connector terminals  
Table 1-10 Terminal connections for different measuring functions  
Rotary switch position  
Input terminals  
V . mV . Ω .  
Overload protection  
COM  
1000 V R.M.S.  
for U1252A  
V for U1251A  
.TEMP  
1000 V R.M.S. for short circuit <0.3 A  
Ω
μA . mA  
COM  
COM  
440 mA / 1000 V 30 kA fast-acting  
fuse  
A
11 A / 1000 V 30 kA fast-acting fuse  
440 mA / 1000 V fast-acting fuse  
for U1252A  
COM  
COM  
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Agilent U1251A and U1252A Handheld Digital Multimeter  
User’s and Service Guide  
2
Making Measurements  
Understanding The Measurement Instructions 24  
Measuring Voltage 24  
Measuring AC voltage 25  
Measuring DC voltage 26  
Measuring Current 27  
µA & mA measurement 27  
Percentage scale of 4 mA to 20 mA 29  
A (ampere) measurement 31  
Frequency Counter 32  
Measuring Resistance, Conductance and Testing Continuity 34  
Testing Diodes 38  
Measuring Capacitance 41  
Measuring Temperature 43  
Alerts and Warning During Measurement 47  
Overload alert 47  
Input warning 47  
Charge terminal alert 48  
This chapter contains information on how to make  
measurements using the U1251A and U1252A handheld  
digital multimeter.  
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Making Measurements  
Understanding The Measurement Instructions  
When making measurements, follow the numerical steps  
labelled in the diagrams. Refer to Table 2-1 below for a  
description of the steps.  
Table 2-1 Numerical steps descriptions  
No.  
Instructions  
Turn the rotary switch to the measurement option shown in the diagram  
Connect the test leads into the input terminals shown in the diagram  
Probe the test points  
Read the results on the display  
Measuring Voltage  
The U1251A and U1252A offer true-RMS readings for AC  
measurements that are accurate for sine waves, square  
waves, triangle waves, staircase waves, and other waveforms  
without any DC offset.  
For AC with DC offset, use AC + DC measurement on  
or  
rotary switch location. This applies only to  
U1252A.  
Ensure that the terminal connections are correct for that particular  
measurement before proceeding with the measurement. To avoid  
damaging the device, do not exceed the input limit.  
WARNING  
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Measuring AC voltage  
Set up the multimeter to measure AC voltage as shown in  
Figure 2-1. Probe the test points and read the display.  
Red Lead  
Black Lead  
Figure 2-1 Measuring AC voltage  
Press  
to display frequency on secondary display. See Table 1-8 of  
NOTE  
“Selecting display with the Dual button” on page 18 for a list of the  
different combinations available on the secondary display.  
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Making Measurements  
Measuring DC voltage  
Set up the multimeter to measure DC voltage as shown in  
Figure 2-2. Probe the test points and read the display.  
MAX  
Red Lead  
Black Lead  
Figure 2-2 Measuring DC voltage  
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Measuring Current  
µA & mA measurement  
Set up the multimeter to measure μA & mA as shown in  
Figure 2-3. Probe the test points and read the display.  
•
•
Press  
if necessary to ensure  
is shown on the display.  
NOTE  
For μA measurement, set the rotary switch to  
the positive test lead to μA.mA.  
and connect  
•
•
•
For mA measurement, set the rotary switch to  
connect the positive test lead to μA.mA.  
and  
For A (ampere) measurement, set the rotary switch to  
connect the positive test lead to A.  
and  
Press  
to display dual measurements. See Table 1-8 of “Selecting  
display with the Dual button” on page 18 for a list of dual  
measurements available. Press and hold  
to exit dual display mode.  
for more than 1 second  
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Making Measurements  
Black Lead  
Red Lead  
Figure 2-3 Measuring μA and mA current  
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Percentage scale of 4 mA to 20 mA  
Set up the multimeter to measure percentage scale as shown  
in Figure 2-4. Probe the test points and read the display.  
•
•
Press  
to select percentage scale display. Ensure that  
or  
NOTE  
is shown on the display.  
The percentage scale for 4 mA to 20 mA or 0 mA to 20 mA is calculated  
using its corresponding DC mA measurement. The U1251A/U1252A  
will automatically optimize the best resolution according to Table 2-2  
below.  
•
Press  
to change the measurement range.  
The percentage scale for 4 mA to 20 mA or 0 mA to 20 mA  
is set to two ranges as follows:  
Table 2-2 Percentage scale and measurement range  
Percentage scale (4 mA to 20 or 0 mA to 20 mA)  
Always auto range  
DC mA auto or manual  
range  
999.99%  
9999.9%  
50 mA, 500 mA  
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Making Measurements  
Black Lead  
Red Lead  
Figure 2-4 Measuring scale of 4-20 mA  
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A (ampere) measurement  
Set up the multimeter to measure A (ampere) as shown in  
Figure 2-5. Probe the test points and read the display.  
Connect the red and black test leads to the 10 A input terminal A and COM  
respectively. The meter is set to A measurement automatically when the  
red test lead is plugged into the A terminal.  
NOTE  
Black Lead  
Red Lead  
Figure 2-5 A (ampere) current measurement  
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Making Measurements  
Frequency Counter  
•
•
Use the frequency counter for low voltage applications only. Never use  
the frequency counter for line power system.  
WARNING  
For inputs more than 30 Vpp, you are required to use frequency  
measurement mode available under the current or voltage  
measurement instead of frequency counter.  
Set up the multimeter to measure frequency as shown in  
Figure 2-6. Probe the test points and read the display.  
•
Press  
to select the Frequency counter (Hz) function. “-1-“ on  
NOTE  
the secondary display means the input signal frequency is divided by 1.  
This allows signals of up to a maximum frequency of 985 kHz to be  
measured.  
•
If the reading is unstable or is zero, press  
to select the division  
of the input signal frequency by 100. This allows for a higher frequency  
range of up to 20 MHz to be measured.  
•
•
The signal is out of range if the reading is still unstable after the above  
step.  
While the secondary display shows “-1-“, you may scroll through the  
pulse width (ms), duty cycle (%), and frequency (Hz) measurements by  
pressing  
.
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Making Measurements  
2
Hz  
Black Lead  
Red Lead  
Figure 2-6 Measuring frequency  
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Making Measurements  
Measuring Resistance, Conductance and Testing Continuity  
Disconnect the circuit power and discharge all high-voltage capacitors  
CAUTION  
before measuring the resistance to prevent any possible damage to the  
multimeter or the device under test.  
Set up the multimeter to measure resistance as shown in  
Figure 2-7. Then probe the test points (by shunting the  
resistor) and read the display.  
nS  
Ω
Black Lead  
Red Lead  
Figure 2-7 Measuring resistance  
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Making Measurements  
2
Press  
to scroll through audible continuity, conductance  
and resistance tests as shown in Table 2-8.  
Press  
Audible  
continuity  
Press  
Press  
Figure 2-8 Audible continuity, conductance, and resistance test.  
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2
Making Measurements  
Audible continuity  
In the range of 0–500 Ω, the beeper will sound if the  
resistance value falls below 10 Ω. For other ranges, the  
beeper will sound if the resistance falls below the typical  
values indicated in Table 2-3 below.  
Table 2-3 Audible continuity measurement range  
Measurement range  
500.00 Ω  
Beeper sound threshold  
< 10 Ω  
5.0000 kΩ  
< 100 Ω  
50.000 kΩ  
< 1 kΩ  
500.00 kΩ  
< 10 kΩ  
5.0000 MΩ  
50.000 MΩ  
500.00 MΩ  
< 100 kΩ  
< 1 MΩ  
< 10 MΩ  
Conductance  
Set up the multimeter to measure conductance as shown in  
Figure 2-9. Probe the test points and read the display.  
The conductance measurement enables the measurement of  
very high resistance of up to 100 GΩ.  
As the high-resistance readings are susceptible to noise, you  
can capture the average readings by using the Dynamic  
Recording mode. Refer to the section “Dynamic  
Recording” on page 50 for more information.  
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Making Measurements  
2
nS  
Ω
MAX  
Black Lead  
Red Lead  
Figure 2-9 Conductance measurement  
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2
Making Measurements  
Testing Diodes  
Disconnect the circuit power and discharge all the high-voltage capacitors  
before testing the diodes to prevent any possible damage to the meter.  
CAUTION  
To test a diode, turn the power off to the circuit and remove  
the diode from the circuit. Set up the multimeter as shown  
in Figure 2-10, then use the red probe lead on the positive  
terminal (anode) and use the black probe lead on the  
negative terminal (cathode) and read the display.  
•
•
The cathode is the side with band(s).  
NOTE  
The meter can display the diode’s forward bias of up to approximately  
2.1 V. A typical diode’s forward bias is between the range of 0.3 V to  
0.8 V.  
Next, reverse the probes and measure the voltage across the  
diodes again as shown in Figure 2-11 on page 40. The  
diode’s test result is based on the following:  
• The diode is considered good if the meter displays “OL”  
in reverse bias mode.  
• The diode is considered shorted if the meter displays  
approximately 0 V in both forward and reverse bias  
modes, and the meter beeps continuously.  
• The diode is considered open if the meter displays “OL”  
in both forward and reverse bias modes.  
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Making Measurements  
2
Hz  
Black Lead  
Red Lead  
Figure 2-10 Measuring forward bias of diode  
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2
Making Measurements  
Hz  
Black Lead  
Red Lead  
Figure 2-11 Measuring reverse bias of diode  
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Making Measurements  
2
Measuring Capacitance  
Disconnect the circuit power and discharge all the high-voltage capacitors  
before measuring the capacitance to prevent any possible damage to the  
meter or the device under test. To confirm that the capacitors have  
discharged, use the DC voltage function.  
CAUTION  
The meter measures capacitance by charging the capacitor  
with a known current for a period of time, measuring the  
voltage and then calculating the capacitance. The larger the  
capacitor, the longer the charge time. Below are some tips  
for measuring capacitance:  
• For measuring capacitance greater than 10,000 µF,  
discharge the capacitor first, then select a suitable  
range for the measurement. This will speed up  
measuring time in order to obtain the correct  
capacitance value.  
• For measuring smaller capacitance ranges, press  
with the test leads open to subtract any residual  
capacitance from the meter or the leads.  
means the capacitor is charging.  
discharging.  
means the capacitor is  
NOTE  
Set up the multimeter as shown in Figure 2-12. Use the red  
probe lead on the positive terminal of the capacitor and the  
black probe lead on the negative terminal and read the  
display.  
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2
Making Measurements  
TEMP  
Red Lead  
Black Lead  
Figure 2-12 Capacitance measurements  
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Making Measurements  
2
Measuring Temperature  
Do not bend the thermocouple leads at sharp angles. Repeated bending  
over a period of time may break the leads.  
CAUTION  
The bead type thermocouple probe is suitable for making  
temperature measurements between –20 °C to 200 °C in  
PTFE compatible environments.  
Do not use the bead-type thermocouple probe beyond the  
recommended operating temperature range. Do not immerse  
this thermocouple probe in liquids. For best results, use a  
thermocouple probe designed for each application — an  
immersion probe for liquid or gel and an air probe for air  
measurements.  
Set up the multimeter to measure temperature as shown in  
Figure 2-15 or observe the following steps:  
1 Press  
to select the temperature measurement.  
2 Connect the miniture thermal probe into the  
non-compensation transfer adaptor as shown in  
Figure 2-13.  
3 Connect the thermal probe with the adapter into the  
meter input terminals as shown in Figure 2-14.  
4 For best performance, place the meter in the operating  
environment for at least one hour to stabilize the unit to  
environment temperatures.  
5 Clean the measurement surface and make sure the probe  
is securely touching the surface. Remember to disable the  
applied power.  
6 When measuring above the ambient temperature, move the  
thermocouple along the surface until you get the highest  
temperature reading.  
7 When measuring below ambient temperature, move the  
thermocouple along the surface until you get the lowest  
temperature reading.  
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Making Measurements  
8 For a quick measurement, use the 0 °C compensation  
adapter to see the temperature variation of the  
thermocouple sensor. The 0 °C compensation adapter  
assists in measuring the relative temperature immediately.  
Figure 2-13 Connecting the thermal probe into the non-compensation  
transfer adapter  
Figure 2-14 Connecting the probe with adapter into the multimeter  
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Making Measurements  
2
If you are working in a constantly varying environment,  
where ambient temperatures are not constant, do the  
following:  
1 Press  
to select 0 °C compensation. This gives a  
quick measurement of the relative temperature.  
2 Avoid contact between the thermocouple probe and the  
measurement surface.  
3 After a constant reading is obtained, press  
to set  
the reading as the relative reference temperature.  
4 Touch the measurement surface with the thermocouple  
probe.  
5 Read the display for the relative temperature.  
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Making Measurements  
TEMP  
Figure 2-15 Surface temperature measurement  
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Making Measurements  
2
Alerts and Warning During Measurement  
Overload alert  
For your safety, look out for this alert. When you are alerted,  
immediately remove the test leads from the measuring source.  
WARNING  
The meter provides an overload alert for voltage  
measurements in both auto and manual range modes. The  
meter beeps periodically once the measuring voltage exceeds  
1010 V. For your safety, please be aware of this alert.  
Input warning  
The meter sounds an alert beep when the test lead is  
inserted into the A input terminal but the rotary switch is  
not set to the corresponding mA.A location. The primary  
display indicates a flashing “A- Err” until the test lead is  
removed from the A input terminal. Refer to Figure 2-16.  
Figure 2-16 Input terminal warning  
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2
Making Measurements  
Charge terminal alert  
The meter sounds an alert beep when the  
terminal  
detects a voltage level of more than 5 V and the rotary  
switch is not set to the corresponding  
location. The  
primary display indicates a flashing “Ch.Err” until the lead  
is removed from the  
input terminal.  
Refer to Figure 2-17 below.  
Figure 2-17 Charge terminal alert  
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Agilent U1251A and U1252A Handheld Digital Multimeter  
User’s and Service Guide  
3
Functions and Features  
Dynamic Recording 50  
Data Hold (Trigger Hold) 52  
Refresh Hold 53  
Null (Relative) 55  
Decibel Display 57  
1 ms Peak Hold 59  
Data Logging 61  
Manual logging 61  
Interval logging 63  
Reviewing logged data 65  
Square Wave Output (for U1252A) 67  
Remote Communication 71  
This chapter contains information on the functions and  
features that are available for the U1251A and U1252A  
digital multimeter.  
Agilent Technologies  
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3
Features and Functions  
Dynamic Recording  
The Dynamic Recording mode can be used to detect  
intermittent turn-on or turn-off voltage, current surges or to  
verify measurement performance without you being present  
during the process. While the readings are being recorded,  
you are free to perform other tasks.  
The average reading is useful for smoothing out unstable  
inputs, estimating the percentage of time a circuit is  
operating and verifying circuit performance. The elapsed  
time is shown on the secondary display. The maximum time  
is 99999 seconds. When this maximum time is exceeded, “OL”  
is shown on the display.  
1 Press  
for more than 1 second to enter Dynamic  
Recording mode. The meter is now in continuous mode or  
non-data hold (non-trigger) mode. “MAXMINAVG” and  
the present value of measurement are displayed. The  
multimeter will beep when a new maximum or minimum  
value is recorded.  
2 Press  
to cycle through maximum, minimum,  
average, and present readings. The MAX, MIN, AVG, and  
MAXMINAVG indicators will appear, corresponding to the  
displayed readings.  
3 Press  
or  
for more than 1 second to exit  
Dynamic Recording mode.  
•
•
Press  
to restart the dynamic recording.  
NOTE  
The average value is the true average of all the measured values taken  
in the Dynamic Recording mode. If an overload is recorded, the  
averaging function will stop and the average value becomes  
"OL"(overload).  
is disabled in Dynamic Recording mode.  
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Features and Functions  
3
Press Max Min  
for > 1 sec  
Press Max Min  
Press Max Min for > 1 sec  
or press  
for > 1 sec  
Press Max Min  
Press Max Min for > 1 sec  
or press for > 1 sec  
Press Max Min  
Press Max Min for > 1 sec  
or press  
for > 1 sec  
Figure 3-1 Dynamic recording mode operation  
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3
Features and Functions  
Data Hold (Trigger Hold)  
The data hold function allows the user to freeze the  
displayed digital value.  
1 Press to freeze the displayed value and to enter the  
manual trigger mode. TRIG  
is displayed.  
2 Press  
again to freeze the next value being  
measured. TRIG flashes before the new value is updated  
on the display.  
3 Press and hold  
or  
for more than 1 second to  
quit the data hold function.  
Press  
Press  
Press  
Figure 3-2 Data hold mode operation  
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Features and Functions  
3
Refresh Hold  
The Refresh Hold function allows you to freeze the displayed  
value. The bar-graph is not held and will continue to reflect  
the instantaneous measured value. You can use the Setup  
mode to enable Refresh Hold mode when you are working  
with fluctuating values. This function will auto trigger or  
update the held value with a new measured value and emit  
a tone as a reminder.  
1 Press  
to enter Refresh Hold mode. The present  
symbol will appear.  
value will be held and the  
2 It will be ready to hold a new measured value once the  
variation of measured values exceeds the variation count  
setting. While the multimeter is waiting for a new stable  
value, the  
symbol will flash.  
3 The  
symbol will stop flashing once the new  
measured value is stable and the new value will be  
updated to the display. The symbol will remain on and  
the multimeter will emit a tone to remind you of this.  
4 Press  
again to quit the Refresh Hold function.  
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3
Features and Functions  
Press  
Variation counts  
> setting  
The HOLD sign flashes  
until the measured  
value is stable and  
updated  
Measurement  
is updated  
Press  
to return  
Figure 3-3 Refresh hold mode operation  
•
•
•
For voltage and current measurements, the holding value will not be  
updated if the reading is below 500 counts.  
NOTE  
For resistance and diode measurements, the holding value will not be  
updated if the reading is in “OL” (open state).  
The holding value may not be updated when the reading does not reach  
a stable state for all measurements.  
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Features and Functions  
3
Null (Relative)  
The Null function subtracts a stored value from the present  
measurement and displays the difference between the two.  
1 Press  
to store the displayed reading as the  
reference value to be subtracted from subsequent  
measurements and to set the display to zero. NULL is  
displayed.  
2 Press  
to see the stored reference value. NULL  
flashes for 3 seconds before the display returns to zero.  
3 To exit this mode, press  
while NULL is flashing on  
the display.  
•
•
Null can be set for both auto and manual range settings, but not in the  
event of an overload.  
NOTE  
When taking a resistance measurement and the meter reads a  
non-zero value due to the presence of test leads, use the Null function  
to adjust the display to zero.  
•
When taking a DC voltage measurement, the thermal effect will  
influence the accuracy. Short the test leads and press Null once the  
displayed value is stable in order to zero out the display.  
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3
Features and Functions  
Press  
Press  
Press  
Figure 3-4 Null (relative) mode operation  
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Features and Functions  
3
Decibel Display  
The dBm operation calculates the power delivered to a  
reference resistance relative to 1 mW and can be applied to  
DC V, AC V, and AC + DC V measurements for decibel  
conversion. The voltage measurement is converted to dBm by  
using the following formula:  
The reference resistance may be selected from 1~9999 Ω in  
Setup mode. The default value is 50 Ω.  
The decibel of voltage is calculated with respect to 1 V. The  
equation for the voltage measurement is as follows:  
dBV = 20 log Vin  
10  
1 At the  
,
, or  
rotary switch position,  
press  
to scroll to the dBm measurement on the  
primary display. The secondary display indicates the AC  
voltage measurement.  
If the rotary switch is at the “~ V” position, press  
to switch  
NOTE  
between the dBV and the dBm measurements. The dBm or the dBV  
measurements can be selected at the ACV position. The selection will be  
the reference for other voltage measurements.  
2 Press  
for more than 1 second to exit this mode.  
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Features and Functions  
Press  
Press  
Press  
Press  
Press  
Press  
Press  
Press  
Press  
Press  
Figure 3-5 dBm/dBV display mode operation  
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Features and Functions  
3
1 ms Peak Hold  
The Peak Hold function allows the measurement of peak  
voltage for analysis of components such as power  
distribution transformers and power factor correction  
capacitors. The peak voltage obtained can be used to deter-  
mine the crest factor:  
Crest factor = Peak value/True RMS value  
1 Press  
for more than 1 second to toggle 1 ms Peak  
Hold mode ON / OFF.  
2 Press  
to scroll through maximum and minimum  
MAX indicates the maximum peak,  
MIN indicates the minimum peak.  
peak readings.  
while  
•
•
If the reading is "OL", press  
to re-start the peak-recording measurement.  
to change the measuring range and  
NOTE  
If you need to re-start the peak recording, press  
.
3 Press and hold  
or  
for more than 1 second  
to exit this mode.  
4 According to the measurements shown in Figure 3-6 on  
page 60, the crest Factor will be 2.5048/1.768 =1.416.  
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Features and Functions  
Press  
Press  
Press  
Press  
Press  
Press  
Figure 3-6 1 ms peak hold mode operation  
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Features and Functions  
3
Data Logging  
The data logging function provides the convenience of  
recording test data for future review or analysis. Since data  
is stored in nonvolatile memory, the data remains saved  
even if the multimeter is turned OFF or the battery is  
changed.  
The two options offered are manual (hand) logging and  
interval (time) logging functions, which is determined in the  
Setup mode.  
Data logging records the values on the primary display only.  
To use the data logging function, you will need to connect the multimeter  
to a PC using the U1173A IR-to-USB cable (purchased separately) and  
download the data logging software from Agilent’s website. Please go to:  
http://www.agilent.com/find/hhTechLib to download the software.  
NOTE  
Manual logging  
Firstly, ensure that manual (hand) logging is specified in  
Setup mode.  
1 Press  
for more than 1 second to store the present  
value and function on the primary display to the  
non-volatile memory. The  
and the logging index  
will be indicated. The logging index flashes on the  
secondary display for 3 seconds before returning to  
normal display.  
2 Press and hold  
again for the next value that you  
would like to save into the memory.  
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Features and Functions  
Press  
Press  
Figure 3-7 Hand (Manual) logging mode operation  
The maximum data that can be stored is 100 entries. When the 100 entries  
are filled, the secondary display indicates “FULL”, as shown in Figure 3-8.  
NOTE  
Press  
Figure 3-8 Full Log  
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Features and Functions  
3
Interval logging  
Firstly, ensure that interval (time) logging is specified in  
Setup mode.  
1 Press  
value and function on the primary display into the  
non-volatile memory. The and the logging index will  
for more than 1 second to store the present  
be indicated. The readings are automatically saved into  
the permanent memory at intervals set using the Setup  
mode.  
The maximum data that can be stored is 200 entries. When the 200 entries  
are filled, “FULL” is indicated on the secondary display.  
NOTE  
NOTE  
2 Press  
for more than 1 second to exit this mode.  
When interval (automatic) logging is enabled, all keypad operations are  
disabled, except for the Log function.  
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3
Features and Functions  
Press  
Press  
Press  
Figure 3-9 Interval (Automatic) logging mode operation  
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Features and Functions  
3
Reviewing logged data  
1 Press  
for more than 1 second to enter the Log  
Review mode. The last recorded entry and the last logging  
index are displayed.  
2 Press  
(automatic) logging review mode.  
3 Press to ascend or to descend through the logged  
data. Press to select the first record and press to  
select the last record for quick navigation.  
to switch between hand (manual) and interval  
4 Press  
for more than 1 second at the respective Log  
for more than 1 second to exit mode.  
Review mode to clear logged data.  
5 Press  
6 During the data review in either manual or interval  
logging mode, press  
for more than one second to  
clear all the logged values.  
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3
Features and Functions  
Press  
Press  
Press  
Press  
Press  
Press  
Press  
Press  
Press  
Press  
Press  
Press  
Press  
Press  
Press  
Press  
Press  
Press  
Press  
Figure 3-10 Log review mode operation  
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Features and Functions  
3
Square Wave Output (for U1252A)  
The square wave output function can be used to generate a  
PWM (pulse width modulation) output or provide a synchro-  
nous clock source (baud rate generator). You can also use  
this function to check and calibrate flow-meter displays,  
counters, tachometers, oscilloscopes, frequency converters,  
frequency transmitters, and other frequency input devices.  
1 Turn the rotary switch to  
position. The default  
display setting is 600 Hz on the secondary display and  
50% duty cycle on the primary display.  
2 Press  
or  
to scroll through the available frequencies  
(choose from the available 28 frequencies):  
Frequency (Hz)  
0.5, 1, 2, 5, 10, 15, 20, 25, 30, 40, 50, 60, 75, 80, 100, 120, 150, 200, 240, 300, 400, 480, 600, 800, 1200, 1600,  
2400, 4800  
Pressing  
is the same as pressing  
.
NOTE  
3 Press  
to select the duty cycle (%) on the primary  
to adjust the duty cycle. Duty cycle can  
display.  
4 Press  
or  
be set for 256 steps and each step is 0.390625%. The  
display only indicates the best resolution with 0.001%.  
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Features and Functions  
Figure 3-11 Frequency adjustment for square wave output  
5 Press  
display.  
6 Press  
to select the pulse width (ms) on the primary  
or to adjust the pulse width. The pulse  
width can be set for 256 steps and each step is 1/ (256 x  
Frequency). The display range automatically adjusts in the  
range of 9.9999~9999.9 ms.  
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Features and Functions  
3
Press  
Press  
Press  
Press  
Figure 3-12 Pulse width adjustment for square wave output  
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Features and Functions  
Figure 3-13 Duty cycle adjustment for Square Wave  
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Features and Functions  
3
Remote Communication  
The meter has a bi-directional (full duplex) communication  
capability that speeds data storing from the meter to the PC.  
To use this feature, you are required to use the optional  
IR-USB cable with the application software included in the  
CD or downloadable from the Agilent Web site.  
For details on performing PC to meter remote  
communication click on Help after launching the Agilent GUI  
Data Logger Software or refer to the GUI Data Logger Quick  
Start Guide (U1251-90023) for more information.  
Connect  
to PC  
Figure 3-14 Cable connection for remote communication  
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3
Features and Functions  
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Agilent U1251A and U1252A Handheld Digital Multimeter  
User’s and Service Guide  
4
Changing The Default Setting  
Selecting Setup Mode 74  
Setting Data Logging Mode 78  
Setting Thermocouple Types (U1252A only) 79  
Setting Reference Impedance for dBm Measurement 80  
Setting Minimum Frequency Measurement 81  
Setting Temperature Unit 82  
Setting Auto Power Saving Mode 84  
Setting Percentage (%) Scale Readout 86  
Setting Beep Frequency 87  
Setting Backlight Timer 88  
Setting Baud Rate 89  
Setting Parity Check 90  
Setting Data Bit 91  
Setting Echo Mode 92  
Setting Print Mode 93  
Returning to Default Factory Settings 94  
This chapter shows you how to change the default factory  
settings of the U1251A and U1252A and other available  
setting options  
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4
Changing The Default Setting  
Selecting Setup Mode  
To enter the Setup mode, perform the following steps:  
1 Turn the meter OFF.  
2 From the OFF position, press and hold  
while  
turning the rotary switch to any non-OFF position.  
When you hear a beep, the meter is in Setup mode and you can release  
NOTE  
To change a menu item setting in Setup mode, perform the  
following steps:  
1 Press  
2 Press  
or  
or  
to scroll through the menu items.  
to scroll through the available settings.  
See Table 4-1, “Available setting options in Setup mode,”  
for details of available options.  
3 Press  
to save changes. These parameters will remain  
in the non-volatile memory.  
4 Press  
for more than 1 second to exit Setup mode.  
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Changing The Default Setting  
4
Table 4-1 Available setting options in Setup mode  
Menu Item  
Available setting options  
Description  
Default factory  
setting  
Display  
Description  
Display  
OFF  
Enables Data Hold (manual trigger)  
rHoLd [1]  
500  
Refresh Hold  
Sets the variation count that determines Refresh  
Hold (auto trigger)  
100–1000  
Enables the reset of factory settings by pressing  
rESEt  
dEFAU  
dEFAU  
Reset  
and holding  
for more than 1 second  
Enables auto send of data to the PC continuously  
when set to ON  
Print  
ECHO  
dAtAb  
PArtY  
ON, OFF  
ON, OFF  
OFF  
OFF  
Print  
Echo  
Enables the return of characters to the PC when  
set to ON  
Sets the data bit length for the remote  
communication (remote control with PC)  
7-bit, 8-bit  
En, Odd, nOnE  
8-bit  
nOnE  
Data bits  
Parity check  
Sets the even, odd or no parity check for the  
remote communication (remote control with PC)  
2400 Hz, 4800  
Hz, 9600 Hz,  
19200 Hz  
Sets the baud rate for the remote communication  
(remote control with PC)  
bAUd  
b-Lit  
9600 Hz  
30 s  
Baud rate  
Sets the timer for the auto turn-off for the backlit  
display  
[2]  
1–99 s  
Backlit display  
OFF  
Disables the auto turn-off for the backlit display  
2400 Hz, 1200  
Hz, 600 Hz,  
300 Hz  
Sets the frequency of the meter’s beep sound  
Frequency of beep  
sound of meter  
bEEP  
2400 Hz  
OFF  
Disables the meter’s beep sound  
Sets the % scale readout  
0–20mA, 4–20  
mA  
PErnt  
APF  
4–20 mA  
10 m  
Percentage scale  
Auto power off  
[2]  
Sets the timer for auto power off  
Disables auto power off  
1–99 m  
OFF  
0.5 Hz, 1 Hz, 2  
Hz, 5 Hz  
Minimum frequency  
that can be measured  
Sets the minimum frequency that can be  
measured  
FrEq  
rEF  
0.5 Hz  
50 Ω  
Reference impedance  
for dBm measurement  
Sets the reference impedance for dBm  
measurement  
[2]  
1–9999 Ω  
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4
Changing The Default Setting  
Table 4-1 Available setting options in Setup mode (continued)  
tYPE K  
tYPE J  
Hand  
Sets the thermocouple type to K-type  
[3]  
tYPE K  
Hand  
t.CoUP  
Thermocouple  
Data logging  
Sets the thermocouple type to J-type  
Enables manual data logging  
d-LoG  
[2]  
Sets the interval for automatic data logging  
Sets the temperature measurement to °C but  
1–9999 s  
d-CF  
pressing  
swaps the display to °F  
d-F  
Sets the temperature measurement to °F  
[4]  
d-CF  
tEMP  
Temperature  
Sets the temperature measurement to °F but  
pressing  
d-FC  
d-C  
swaps display to °C  
Sets the temperature measurement to °C  
Notes for setting options in Setup mode:  
1
2
3
4
This is the first option displayed once the user enters Setup mode.  
For b-Lit, APF, rEF and d-LoG menu items, the user can select the digit to be adjusted by pressing  
This menu option is only available for the U1252A.  
To view the tEMP menu item, press  
for more than 1 second.  
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Changing The Default Setting  
4
Setting Data Hold/Refresh Hold Mode  
1. Set OFF to enable the Data Hold mode (manual trigger by  
key or bus via the remote control).  
2. Set the variation count within the 100 to 1000 range to  
enable the Refresh Hold mode (auto trigger). When the  
variation of the measuring value exceeds the setting of the  
variation count the Refresh Hold will be ready to trigger.  
Press  
Press  
Press  
Press  
Press  
Figure 4-1 Data hold/Refersh hold setup  
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4
Changing The Default Setting  
Setting Data Logging Mode  
1 Set to “Hand” to enable the manual data logging mode.  
2 Set the interval within 0001 to 9999 seconds to enable  
interval (automatic) data logging mode.  
3 Press and hold  
or  
for more than 1 second to switch  
between manual and interval data logging setup.  
Press  
Press  
Press  
Press  
Press  
Press  
Figure 4-2 Data logging setup  
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Changing The Default Setting  
4
Setting Thermocouple Types (U1252A only)  
The thermocouple sensor types that can be selected are  
type-K (default) or type-J. Press  
between the J and the K type.  
or  
to switch  
Press  
Figure 4-3 Thermocouple type setup  
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4
Changing The Default Setting  
Setting Reference Impedance for dBm Measurement  
The reference impedance can be set from 1 to 9999 W. The  
default value is 50 W.  
Press  
Press  
Press  
Press  
Figure 4-4 Reference impedance for dBm measurement setup  
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Changing The Default Setting  
4
Setting Minimum Frequency Measurement  
The minimum frequency setup influences the measuring  
rates for frequency, duty cycle, and pulse width. The typical  
measuring rate defined at the general specification is based  
on the minimum frequency of 1 Hz.  
Press  
Press  
Press  
Press  
Press  
Figure 4-5 Minimum frequency setup  
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4
Changing The Default Setting  
Setting Temperature Unit  
Four combination displays are available:  
• Celsius only (°C on primary display) single display setting  
• Celsius-Fahrenheit (d-CF) and Fahrenheit-Celsius (d-FC)  
dual display setting.  
Primary-Secondary Display can be swapped by pressing  
.
NOTE  
• Fahrenheit only (°F on primary display) single display  
setting.  
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Changing The Default Setting  
4
Press  
Press  
Press  
Press  
Press  
Figure 4-6 Temperature unit setup  
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4
Changing The Default Setting  
Setting Auto Power Saving Mode  
• The timer for APF (Auto Power OFF) can be set for the  
range of 1 to 99 minutes.  
• To activate the meter after it has “auto powered-off”, turn  
the rotary switch to the OFF position. Then turn it back  
on again.  
•
will be shown on the display during subsequent  
measurements.  
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Changing The Default Setting  
4
Press  
Press  
Press  
Press  
Press  
Figure 4-7 Auto power saving setup  
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4
Changing The Default Setting  
Setting Percentage (%) Scale Readout  
This setting converts the DC current measuring display to  
percentage (%) scale readout — 4—20 mA or 0—20 mA as  
proportional to 0~100%. The 25% scale readout represents  
DC 8 mA at 4—20 mA and DC 5 mA at 0—20 mA.  
Press  
Figure 4-8  
% scale readout setup  
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Changing The Default Setting  
4
Setting Beep Frequency  
The driving frequency can be set to 2400, 1200, 600,  
or 300Hz. “OFF” disables the beep.  
Press  
Press  
Press  
Press  
Press  
Press  
Figure 4-9 Beep frequency setup  
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4
Changing The Default Setting  
Setting Backlight Timer  
• The timer can be set to 1 to 99 seconds. The backlight  
will turn off automatically after the set period.  
• “0FF” disables turning off backlit automatically.  
Press  
Press  
Press  
Press  
Press  
Figure 4-10 Backlit timer setup  
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Changing The Default Setting  
4
Setting Baud Rate  
Select the baud rate for remote control. The available  
settings are 2400, 4800, 9600, and 19200 Hz.  
Press  
Press  
Press  
Press  
Press  
Figure 4-11 Baud rate setup remote control  
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4
Changing The Default Setting  
Setting Parity Check  
Select the parity check for remote control. It can be set to  
none, even, or odd bit.  
Press  
Press  
Press  
Press  
Figure 4-12 Parity check setup  
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Changing The Default Setting  
4
Setting Data Bit  
Select the data bit for remote control. It can be set to either  
8 or 7 bits.  
Press  
Figure 4-13 Data bit setup for remote control  
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4
Changing The Default Setting  
Setting Echo Mode  
• Echo ON enables the return of characters to the PC in  
remote communication.  
• Echo OFF disables the return of characters to the PC.  
Press  
Figure 4-14 Echo mode setup for remote control  
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Changing The Default Setting  
4
Setting Print Mode  
Print ON enables the printing of measured data to the PC  
when the measuring cycle is completed. In this mode, the  
meter automatically sends the newest data to the host  
continuously but does not accept any commands from the  
host.  
flashes during the Print operation.  
Press  
Figure 4-15 Print mode setup for remote control  
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4
Changing The Default Setting  
Returning to Default Factory Settings  
• Press  
for more than 1 second to reset to the  
default factory settings all menu options except the  
Temperature setting.  
• The Reset menu item automatically reverts to Refresh  
Hold menu item after reset has taken place.  
Press  
for > 1 sec  
Figure 4-16 Reset setup  
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Agilent U1251A and U1252A Handheld Digital Multimeter  
User’s and Service Guide  
5
Maintenance  
Introduction 96  
General maintenance 96  
Battery replacement 96  
Storage considerations 98  
Charging the battery 98  
Fuse checking procedure 105  
Replacing the fuse 106  
Troubleshooting 108  
Replaceable Parts 109  
To order replaceable parts 109  
This chapter will go through how to troubleshoot the  
handheld digital multimeter if any problems arise.  
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5
Maintenance  
Introduction  
Any repair or service which is not covered in this manual should only  
be performed by qualified personnel.  
CAUTION  
General maintenance  
Ensure that the terminal connections are correct for that particular  
measurement before proceeding. To avoid damaging the device, do not  
exceed the input limit.  
WARNING  
Besides the above hazard, dirt, or moisture in the terminals  
can distort readings. The steps for cleaning are as follows:  
1 Turn the meter off and remove the test leads.  
2 Turn the meter over and shake out any dirt that may  
have accumulated in the terminals.  
3 Wipe the case with a damp cloth and a mild detergent —  
do not use abrasives or solvents. Wipe the contacts in  
each terminal with a clean swab dipped in alcohol.  
Battery replacement  
The meter is powered by a 9 V Ni-MH rechargeable battery,  
7.2 V nominal voltage. Use only the specified type (refer to  
Figure 5-1 below).  
To ensure that the correct battery type is used, replace the  
battery immediately when the low battery sign flashes. If  
your meter has the rechargeable battery type, refer to the  
section “Charging the battery” on page 98. The steps for  
battery replacement are listed below:  
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Maintenance  
5
Figure 5-1 9 V rectangular battery  
1 At the rear panel, turn the screw on the battery cover  
from the LOCK to the OPEN position (counterclockwise).  
2 Slide down the battery cover.  
3 Lift the battery cover up.  
4 Replace the specified battery.  
5 Reverse the above steps to close the cover.  
List of compatible batteries for the Agilent U1251A :  
NOTE  
• 9 V Alkaline non-chargeable battery (ANSI/NEDA 1604A or IEC 6LR61)  
• 9 V Carbon-zinc non-chargeable battery (ANSI/NEDA 1604D or IEC6F22)  
List of of compatible batteries for the Agilent U1252A:  
• 9 V size 300 mAH Ni-MH rechargeable battery, 7.2 V nominal voltage, or  
8.4 V nominal voltage  
• 9 V Alkaline non-chargeable battery (ANSI/NEDA 1604A or IEC 6LR61)  
• 9 V Carbon-zinc non-chargeable battery (ANSI/NEDA 1604D or IEC6F22)  
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5
Maintenance  
Storage considerations  
To avoid instrument damage from battery leakage:  
CAUTION  
•
•
Always remove dead batteries immediately.  
It is recommended that the battery is removed and stored separately if  
the multimeter is to be unused for long periods of time.  
After the first charge, it is recommended that you fully  
charge the battery periodically, even when it is not in use.  
This is because the Ni-MH rechargeable battery pack may  
drain with time.  
The performance of the rechargeable battery may degrade with time.  
NOTE  
Charging the battery  
Never discharge the battery by shorting it or by reverse polarity in any  
WARNING  
subjects. Make sure the battery is the rechargeable type before  
charging it. Never rotate the rotary switch when the battery is being  
charged as DC at 24 V is being applied to the charging terminals.  
For the battery charger, the mains supply voltage should not fluctuate by  
plus or minus 10%.  
NOTE  
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Maintenance  
5
CAUTION  
•
•
Do not rotate the rotary switch from  
charging the battery.  
position when  
Perform battery charging only with a 9 V Ni-MH rechargeable  
battery (7.2 V nominal voltage) or 9 V size Ni-MH rechargeable  
battery (8.4 V nominal voltage).  
•
•
Disconnect test leads from all the terminals when charging.  
Ensure proper insertion of battery in the multimeter and follow the  
correct polarity.  
Use the specified 24 V DC adaptor to charge the battery.  
Remember never to turn the rotary switch of the meter  
when the battery is being charged. Use the following steps to  
charge the battery:  
1 Disconnect the test leads from the meter.  
2 Turn the rotary switch to the  
position. Connect  
the power cord to the DC adapter.  
3 Plug the Red (+)/ Black (–) banana terminals of the DC  
adapter to the and the “COM” terminals  
respectively. The DC adaptor can be replaced with a DC  
power supply in order to set the 24 V DC output and the  
over current limitation to a value more than 0.5 A.  
Ensure that the polarity of the connection is correct.  
4 The primary display will show “bAt” and the ‘SbY” will be  
shown on the secondary display and a short beep will  
sound to remind you whether you need to charge the  
battery. Press SHIFT to start charging the battery, or the  
meter will automatically start the self-test after the 24 V  
supply is applied. It is recommended that you do not  
charge if the battery’s capacity is over 90%.  
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5
Maintenance  
Table 5-1 Battery voltage and corresponding percentage of charges in standby and charging modes  
Condition  
Trickle (SBY)  
Charging  
Battery voltage  
6.0 V to 8.2 V  
7.2 V to 10.0 V  
Proportional percentage  
0% to 100%  
0% to 100%  
Figure 5-2 Battery capacity display as trickle  
5 After pressing Shift or when the self-test starts, the meter  
performs a self-test to check if the battery in the meter is  
the rechargeable type. The self-test takes about 2 to 3  
minutes. Avoid pressing any button during the self-test. A  
message is diplayed as shown below.  
Figure 5-3 Self-test  
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Maintenance  
5
Table 5-2 Error messages  
Error  
Error message  
OL  
1
2
3
No battery inside  
Faulty battery  
Battery is fully charged  
C-Err  
1
2
If charging battery more than 12 V or  
less than 5 V  
In 3 minutes, if the battery voltage  
does not go upwards then charge  
error  
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5
Maintenance  
•
•
If the OL message appears while the battery is inside, do not charge the battery.  
If the C-Err message appears, check if the battery is the specified type. Use the  
battery as specified in this manual. Ensure that the battery is the correct  
rechargeable type before charging it again. After replacing with the correct  
rechargeable battery, press Shift to perform the self-test again. If the C-Err  
message reappears, replace with a new battery.  
NOTE  
6 The smart charging mode will start if the meter passes  
the self-test. The charging time is limited to not more  
than 220 minutes. The secondary display will count down  
the charging time. During charging, no buttons can be  
pressed. The error message may appear during charging to  
alert the user of any overcharging of the battery.  
Figure 5-4 Charging mode  
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Maintenance  
5
7 The charge end message (C–End) appears on the  
secondary display once charging is completed. The trickle  
charging current is provided to maintain the battery  
capacity. The flashing signs of  
show the trickle state.  
and  
appear to  
8 Remove the DC adapter when the C–End message appears  
on the secondary display. Do not turn the rotary switch  
before removing the adapter from the terminals.  
Figure 5-5 Charge end and trickle state  
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5
Maintenance  
Press  
Figure 5-6 Battery charging procedure  
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Maintenance  
5
Fuse checking procedure  
It is recommended that you check the fuses of the  
multimeter before using it. Follow the instructions below to  
test the fuses inside the multimeter. Refer to Figure 5-8 for  
the respective positions of Fuse 1 and Fuse 2.  
1 Set the rotary switch to  
.
2 Connect the red test lead to the input terminal  
.
3 To test Fuse 1, place the tip of the test probe on the right  
half of input terminal  
. Ensure that the probe tip  
touches the metal inside the input terminal, as shown in the  
figure above.  
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5
Maintenance  
4 To test Fuse 2, place and touch the tip of the test probe  
on the right half of input terminal . Ensure that the  
probe tip touches the metal inside the input terminal.  
5 Observe the reading on the instrument's display. Refer to  
Table 5-3 for the possible readings that could appear).  
6 Replace the fuse when OL is displayed.  
Table 5-3 Measurement readings for fuse checking  
Fuse OK (approximately)  
Replace fuse  
Current input terminal  
Fuse  
Fuse rating  
Displayed readings  
1
2
440 mA/1000 V  
11 A/1000 V  
6.2 MΩ  
0.06 Ω  
OL  
OL  
Replacing the fuse  
This manual provides only the fuse replacement procedures, but not the  
fuse replacement markings.  
NOTE  
Follow the procedures below to replace the fuse.  
1 Turn the meter off and disconnect the test leads from the  
external equipment. Make sure to remove the adaptor.  
2 Wear clean/dry gloves and do not touch any other  
component except the fuse and plastic parts. The current  
calibration is considered shunt only, so do not recalibrate  
the meter after replacing the fuse.  
3 Remove the battery cover compartment to replace the  
fuse.  
4 Loosen the three screws on the bottom case and remove  
the cover.  
5 Loosen the two screws on the top corners to lift the  
circuit board.  
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Maintenance  
5
6 Gently remove the defective fuse by prying one end of the  
fuse loose and removing it out of the fuse bracket.  
7 Replace with a new fuse of the same size and rating.  
Make sure the new fuse is centered in the fuse holder.  
8 Ensure that the rotary switch on the top case and the  
circuit board switch stay on the OFF position.  
9 Then re-fasten the circuit board and the bottom cover.  
10 Refer to the table below for the part number, rate, and  
size of the fuses.  
Table 5-4 Fuse specifications  
Fuse  
Agilent part number  
Rating  
Size  
Type  
1
2
2110-1400  
2110-1402  
440 mA/1000 V  
11 A/1000 V  
10 mm × 35 mm  
10 mm × 38 mm  
Fast blow fuse  
Fuse 1  
Fuse 2  
Figure 5-7 Fuse replacement  
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5
Maintenance  
Troubleshooting  
To avoid electrical shock, do not perform any service unless you are  
qualified to do so.  
WARNING  
If the instrument fails to operate, check the battery and the  
test leads. Replace them if necessary. And if the instrument  
still does not function, check the operating procedures in  
this manual. When servicing, use only specified replacement  
parts. Table 5-5 below will assist you to identify some basic  
problems and their solutions.  
Table 5-5 Basic troubleshooting procedures  
Malfunction  
Troubleshooting procedure  
Check the battery. Charge or replace it.  
•
•
No LCD display after power ON  
No beeper tone  
Check the setup mode to verify if the beeper is set to OFF. Then select the  
desired driving frequency.  
•
Check the fuse.  
Fail on current measurement  
•
•
Check 440 mA fuse.  
[1]  
No charging indication  
Check the external adaptor to verify if the output is DC 24 V and the adaptor is  
plugged into the charging terminals completely.  
Line power voltage (100V~240 VAC 50 Hz/ 60 Hz).  
•
•
•
Check if the correct rechargeable battery is used.  
Try to charge and discharge for 2 or 3 cycles in order to maintain the battery’s  
highest capacity.  
Battery life very short after full  
charge/Battery not able to charge  
after pro-long storage period  
• NOTE: The performance of the rechargeable battery may degrade with time.  
•
Check that the optical side of the cable is connected to the meter and the text  
side of the cover is up.  
Fail on Remote control  
•
•
Check the baud rate, parity, Data bit, Stop bit (default is 9600, n, 8, 1)  
Driver install for IR-USB.  
Notes for basic troubleshooting procedures table:  
Never turn the rotary switch of the multimeter from the OFF position when it is charging.  
1
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Maintenance  
5
Replaceable Parts  
This section contains information for ordering replacement  
parts for your instrument. you can find the instrument  
support part list at Agilent’s Test & Measurement Parts  
Catalog at: http://www.agilent.com/find/parts  
The parts lists include a brief description of each part with  
applicable Agilent part number.  
To order replaceable parts  
You can order replaceable parts from Agilent using the  
Agilent part number. Note that not all parts listed are  
available as field-replaceable parts.  
To order replaceable parts from Agilent, do the following:  
1 Contact your nearest Agilent Sales Office or Service  
Center.  
2 Identify the parts by the Agilent part number shown in  
the support parts list.  
3 Provide the instrument model number and serial number.  
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Maintenance  
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User’s and Service Guide  
6
Performance Tests and Calibration  
Calibration Overview 112  
Closed-case electronic calibration 112  
Agilent Technologies calibration services 112  
Calibration interval 113  
Adjustment is recommended 113  
Recommended Test Equipment 114  
Basic Operating Test 115  
Backlit test 115  
Testing the display 115  
Current terminal test 116  
Charge terminal alert test 117  
Test Considerations 118  
Calibration Security 119  
Performance Verification Tests 120  
Unsecuring the instrument for calibration 128  
Calibration process 131  
Using the front panel for adjustments 132  
Adjustments Consideration 133  
Valid adjustment input values 134  
Adjustment procedure 135  
Finishing the adjustment 142  
Calibration errors 143  
This chapter contains the performance test and the  
adjustment procedure.  
Agilent Technologies  
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Performance Tests and Calibration  
Calibration Overview  
This manual contains procedures to verify the instrument’s  
performance and adjustment (calibration).  
The performance test procedures allow you to verify that the  
handheld digital multimeter is operating within its published  
specifications. The adjustment procedures ensure that the  
multimeter remains within its specifications until the next  
calibration.  
Make sure you have read the “Test Considerations” on page 118 before  
calibrating the instrument.  
NOTE  
Closed-case electronic calibration  
This instrument features closed-case electronic calibration.  
No internal mechanical adjustments are required. The  
instrument calculates correction factors based upon the  
input reference value you set. The new correction factors are  
stored in the nonvolatile memory until the next calibration  
adjustment is performed. The nonvolatile EEPROM  
calibration memory is retained even when the power is  
switched off.  
Agilent Technologies calibration services  
When your instrument is due for calibration, contact your  
local Agilent Service Center to enquire about recalibration  
services.  
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Calibration interval  
A 1-year interval is adequate for most applications. Accuracy  
specifications are warranted only if adjustment is made at  
regular calibration intervals. Accuracy specifications are not  
warranted beyond the 1-year calibration interval. Agilent  
does not recommend extending calibration intervals beyond  
2 years for any application.  
Adjustment is recommended  
Specifications are only guaranteed within the period stated  
from the last adjustment. Agilent recommends that  
readjustment should be performed during the calibration  
process for best performance. This will ensure that the  
U1251A/U1252A will remain within the specifications for the  
next calibration interval. This criterion for the re-adjustment  
provides the best long–term stability.  
Performance data are measured during the Performance  
Verification Tests but this does not guarantee that the  
instrument will remain within these limits unless the  
adjustments are performed.  
Refer to the section “To read the calibration count” on  
page 142 and verify that all the adjustments have been  
performed.  
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Performance Tests and Calibration  
Recommended Test Equipment  
The test equipment recommended for the performance  
verification and adjustment procedures is listed below. If the  
exact instrument is not available, substitute calibration  
standards of equivalent accuracy.  
A suggested alternative method would be to use the Agilent  
3458A 8½ – Digit Digital Multimeter to measure less  
accurate yet stable sources. The output value measured from  
the source can be entered into the instrument as the target  
calibration value.  
Table 6-1 Recommended Test Equipment  
Application  
DC Voltage  
DC Current  
Resistance  
AC Voltage  
AC Current  
Frequency  
Capacitance  
Duty Cycle  
Nanosiemens  
Diode  
Recommended equipment  
Fluke 5520A  
Recommended accuracy requirements  
<1/5 instrument 1 year spec  
<1/5 instrument 1 year spec  
<1/5 instrument 1 year spec  
<1/5 instrument 1 year spec  
<1/5 instrument 1 year spec  
<1/5 instrument 1 year spec  
<1/5 instrument 1 year spec  
<1/5 instrument 1 year spec  
<1/5 instrument 1 year spec  
<1/5 instrument 1 year spec  
Fluke 5520A  
Fluke 5520A  
Fluke 5520A  
Fluke 5520A  
Agilent 33250A  
Fluke 5520A  
Fluke 5520A  
Fluke 5520A  
Fluke 5520A  
Frequency  
Counter  
Agilent 33250A  
<1/5 instrument 1 year spec  
Temperature  
Square Wave  
Fluke 5520A  
<1/5 instrument 1 year spec  
<1/5 instrument 1 year spec  
Agilent 53131A and Agilent 34401A  
Shorting Plug - Dual banana plug with copper wire  
short between 2 terminal  
Short  
–
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Basic Operating Test  
The Basic Operating Test is to test the basic operability of  
the instrument. Repair is required if the instrument fails the  
Basic Operating Test.  
Backlit test  
Press the Bat button to test the backlight. It will  
momentarily toggle backlit ON and OFF.  
Testing the display  
Press the Hold button and turn on the meter to view all  
segments of the display. Compare the display with the  
example in Figure 6-1.  
Figure 6-1 LCD display  
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Performance Tests and Calibration  
Current terminal test  
This test determines if the input warning of the current  
terminal test is functioning properly.  
The meter sounds an alert beep when the test lead is  
inserted into the A terminal but the rotary switch is not set  
to mA.A function. The primary display will indicate “A-Err”  
as shown in Figure 6-2. The primary display will keep flash-  
ing unless the test lead is removed from “A” terminal.  
Before conducting this test, make sure the beep function is not disabled in  
setup.  
NOTE  
Figure 6-2 Input warning  
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Charge terminal alert test  
This test determines if the charge terminal alert is operating  
properly.  
The meter sounds an alert when the  
terminal  
detects a voltage level of more than 5 V and the rotary  
switch is not set to the  
position. The meter sounds  
an alert beep and the primary display flashes the “Ch.Err”  
until the lead is removed from the  
terminal.  
Figure 6-3 Charge terminal alert  
Before conducting this test, make sure the beep function is not disabled at  
setup.  
NOTE  
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Performance Tests and Calibration  
Test Considerations  
Long test leads can also act as antennas which may pick up  
AC signals.  
For optimum performance, all procedures should comply  
with the following recommendations:  
• Ensure that the calibration ambient temperature is stable  
and is between 18 °C and 28 °C. Ideally the calibration  
should be performed at 23 °C 1 °C.  
• Ensure that the ambient relative humidity is less than  
80%.  
• Allow a warm-up period of five minutes.  
• Use shielded twisted pair PTFE-insulated cables to reduce  
settling and noise errors. Keep the input cables as short  
as possible.  
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7
Calibration Security  
The calibration security code prevents accidental or  
unauthorized adjustments to the instrument. When you first  
receive your instrument, it is secured. Before you can adjust  
the instrument, you must unsecure it by entering the correct  
security code (see “Unsecuring the instrument for  
calibration” on page 128).  
The security code is set to 1234 when the instrument is  
shipped from the factory. This code is stored in nonvolatile  
memory, and does not change when power is turned off.  
The security code may contain up to 4 numeric characters.  
You can unsecure the instrument from the front panel. The security code  
can only be changed from the front panel after the instrument has been  
unsecured.  
NOTE  
See “To unsecure the instrument without the security code” on page 130 if  
you forget your security code.  
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Performance Tests and Calibration  
Performance Verification Tests  
Use the Performance Verification Tests to verify the  
measurement performance of the instrument. The  
performance verification tests use the instrument’s  
specifications listed in the U1251A/U1252A Data Sheet.  
The performance verification tests are recommended as  
acceptance tests when you first receive the instrument. The  
acceptance test results should be compared against the one  
year test limits. After acceptance, you should repeat the  
performance verification tests at every calibration interval.  
Make sure you have read the “Test Considerations” on page 118 before  
doing the performance verification tests.  
NOTE  
Perform the verification test steps in the following Table 6-2  
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7
Table 6-2 Performance verification test steps  
Error from nominal 1 year  
Step  
Test Function  
Range  
5520A Output  
U1251A  
32.5 mV  
U1252A  
22.5 mV  
1
Turn the rotary switch to the  
5 V  
5 V, 1 kHz  
[1]  
V position  
5 V, 10 kHz  
5 V, 20 kHz  
5 V, 30 kHz  
52.5 mV  
N/A  
84 mV  
22.5 mV  
41.5 mV  
N/A  
4.5 V, 100 kHz N/A  
169.5 mV  
225 mV  
225 mV  
415 mV  
50 V  
50 V,1 kHz  
325 mV  
525 mV  
N/A  
840 mV  
N/A  
50 V,10 kHz  
50 V, 20 kHz  
50 V, 30 kHz  
45 V, 100 kHz  
500 V, 1 kHz  
500 V, 10 kHz  
1000 V, 1 kHz  
0.48 V, 1 kHz  
N/A  
1.695 V  
2.25 V  
2.25V  
500 V  
3.25 V  
5.25 V  
10 V  
1000 V  
8.0 V  
2
3
Press  
frequency mode  
button to go to  
9.9999 kHz  
500 mHz  
500 mHz  
Press  
button to go to  
0.01% – 99.99%  
5.0 Vpp @  
0.315%  
0.315%  
Duty Cycle mode  
50%, Square  
Wave, 50 Hz  
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Performance Tests and Calibration  
Error from nominal 1 year  
Step  
Test Function  
Range  
5520A Output  
U1251A  
2 mV  
U1252A  
1.75 mV  
4
Turn the rotary switch to  
5 V  
5 V  
V position (for model U1252A), to  
V position (for model  
U1251A)  
50 V  
50 V  
20 mV  
17.5 mV  
200 mV  
800 mV  
22.5 mV  
500 V  
1000 V  
5 V  
500 V  
200 mV  
800 mV  
1000 V  
5 V,1 kHz  
5
Press  
button to go to the  
V mode  
N/A  
[1]  
5 V, 10 kHz  
5 V, 20 kHz  
N/A  
N/A  
22.5 mV  
41.5 mV  
4.5 V, 100 kHz N/A  
169.5 mV  
225 mV  
225 mV  
415 mV  
1.695 V  
2.25 V  
50 V  
50 V, 1 kHz  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
50 V, 10 kHz  
50 V, 20 kHz  
45 V, 100 kHz  
500 V, 1 kHz  
500 V, 10 kHz  
1000 V, 1 kHz  
500 V  
2.25 V  
1000 V  
8.0 V  
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Error from nominal 1 year  
7
Step  
Test Function  
Range  
5520A Output  
U1251A  
U1252A  
[2]  
[2]  
6
Turn the rotary switch to the  
mV position  
50 mV  
50 mV  
75 μV  
75 μV  
500 mV  
1000 mV  
50 mV  
500 mV  
0.2 mV  
0.2 mV  
0.8 mV  
0.8 mV  
0.34 mV  
0.175 mV  
0.175 mV  
0.75 mV  
0.75 mV  
0.24 mV  
– 500 mV  
1000 mV  
– 1000 mV  
50 mV, 1 kHz  
7
Press  
the  
button to go to  
mV mode  
[1]  
50 mV, 10 kHz  
50 mV, 20 kHz  
50 mV, 30 kHz  
45 mV, 100 kHz  
500 mV, 45 Hz  
500 mV, 1 kHz  
500 mV, 10 kHz  
500 mV, 20 kHz  
500 mV, 30 kHz  
450 mV, 100 kHz  
1000 mV, 1 kHz  
1000 mV, 10 kHz  
1000 mV, 20 kHz  
1000 mV, 30 kHz  
1000 mV, 100 kHz  
0.54 mV  
0.39 mV  
N/A  
0.86 mV  
N/A  
0.415 mV  
N/A  
1.695 mV  
2.25 mV  
2.25 mV  
2.25 mV  
4.15 mV  
500 mV  
3.25 mV  
3.25 mV  
5.4 mV  
N/A  
8.6 mV  
N/A  
N/A  
16.95 mV  
6.5 mV  
1000 mV  
8.5 mV  
12.5 mV  
6.5 mV  
N/A  
20.0 mV  
N/A  
11.5 mV  
N/A  
47 mV  
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Performance Tests and Calibration  
Error from nominal 1 year  
Step  
Test Function  
Range  
5520A Output  
U1251A  
U1252A  
[3]  
[3]  
8
Turn the rotary switch to the W  
500 W  
500 W  
500 mW  
350 mW  
position  
[3]  
[3]  
5 kW  
5 kW  
4.5 W  
45 W  
3 W  
50 kW  
500 kW  
5 MW  
50 MW  
50 kW  
500 kW  
5 MW  
30 W  
450 W  
300 W  
10.5 kW  
8 kW  
[4]  
50 MW  
450 MW  
50 nS  
0.510 MW  
0.505 MW  
36.1 MW  
0.6 nS  
500 MW  
N/A  
[5]  
9
Press  
mode  
button to go to ns  
500 nS  
0.7 nS  
10  
Turn the rotary switch to the Hz/  
position (for model  
Diode  
1 V  
1 mV  
1 mV  
U1252A), to  
position (for  
model U1251A)  
33250A Output  
11  
12  
Press  
button to go to  
999.99 kHz  
99.999 MHz  
200 mVrms,  
100 kHz  
N/A  
52 Hz  
[6]  
frequency counter mode  
Press  
button to go to  
600 mVrms,  
10 MHz  
N/A  
5.2 kHz  
frequency counter mode divide  
by 100  
5520A Output  
13  
Turn the rotary switch to the  
10.000 nF  
10.000 nF  
0.108 nF  
0.108 nF  
[7]  
TEMP/  
position  
100.00 nF  
1000.0 nF  
10.000 μF  
100.00 nF  
1000.0 nF  
10.000 μF  
1.05 nF  
10.5 nF  
0.105 μF  
1.05 nF  
10.5 nF  
0.105 μF  
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Error from nominal 1 year  
7
Step  
Test Function  
Range  
5520A Output  
U1251A  
1.05 μF  
U1252A  
1.05 μF  
100.00 μF  
1000.0 μF  
10.00 mF  
100.00 mF  
100.00 μF  
1000.0 μF  
10.00 mF  
10.00 mF  
0 ºC  
10.5 μF  
0.105 mF  
0.4 mF  
3 ºC  
10.5 μF  
0.105 mF  
0.4 mF  
3 ºC  
14  
15  
16  
Press  
TEMP mode  
button to go to  
–200 ºC until  
1372 ºC  
[8][13]  
100 ºC  
3.3 ºC  
3.3 ºC  
[9]  
[9]  
Turn the rotary swich to the  
uA position  
500 μA  
500 μA  
0.55 μA  
0.3 μA  
[9]  
[9]  
5000 μA  
500 μA  
5000 μA  
5.5 μA  
4.2 μA  
3 μA  
Press  
button to go to  
500 μA, 1 kHz  
3.7 μA  
[1]  
uA mode  
500 μA, 20 kHz  
5000 μA, 1 kHz  
5000 μA, 20 kHz  
50 mA  
15.8 μA  
42 μA  
3.95 μA  
37.0 μA  
39.5 μA  
5000 μA  
0.156 mA  
0.105 mA  
[9]  
[9]  
17  
18  
Turn the rotary switch to the  
mA.A position  
50 mA  
80 μA  
[9]  
[9]  
440 mA  
50 mA  
400 mA  
0.93 mA  
0.42 mA  
0.71 mA  
0.37 mA  
Press  
button to go to  
50 mA, 1 kHz  
[1]  
mA mode  
50 mA, 20 kHz  
400 mA, 45 Hz  
400 mA, 1 kHz  
1.56 mA  
3.4 mA  
3.4 mA  
0.395 mA  
3.0 mA  
440 mA  
3.0 mA  
Caution: Connect calibrator to hanheld multimeter's A and COM terminal before applying 5A and 10A  
5 A  
5 A  
16 mA  
40 mA  
16 mA  
35 mA  
[10]  
10 A  
10 A  
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Performance Tests and Calibration  
Error from nominal 1 year  
Step  
Test Function  
Range  
5520A Output  
U1251A  
42 mA  
U1252A  
37 mA  
19  
Press  
button to go to  
A mode  
5 A  
5 A, 1 kHz  
3A  
3 A, 5 kHz  
96 mA  
96 mA  
90 mA  
[11]  
10 A  
10 A, 1 kHz  
Use 53131A  
100 mA  
Square Wave  
Output  
20  
Turn the rotary switch to the  
position  
120 Hz @ 50%  
N/A  
26 mHz  
4800 Hz @ 50%  
100 Hz @ 50%  
100 Hz @ 25%  
100 Hz @ 75%  
N/A  
N/A  
N/A  
N/A  
260 mHz  
[12]  
Duty Cycle  
0.398%  
0.398%  
0.398%  
[12]  
[12]  
Use 34410A  
Amplitude  
4800 Hz @  
99.609%  
N/A  
0.2V  
Notes for verification test:  
1
2
The additional error to be added as frequency > 20 kHz and signal input < 10% of range: 300 counts of LSD per kHz.  
The accuracy could be 0.05% + 10, always use relative function to zero thermal effect (short test leads) before measuring  
the signal.  
3
4
5
6
The accuracy of 500 W and 5 kW is specified after the Null function.  
For range of 50 MW, the RH is specified for < 60%.  
The accuracy is specified for < 50 nS and after Null function as open test lead.  
All frequency counters are susceptible to error when measuring low voltage, low-frequency signals. Shielding inputs from  
external noise pickup is critical for minimizing measurement errors.  
7
8
Use the Null mode to zero residual.  
The accuracy does not include the tolerance of the thermocouple probe. The thermal sensor plugged into the meter should  
be placed in the operating enviroment for at least an hour. Use the Null function to reduce the thermal effect.  
Always use relative function to zero the thermal effect with open test lead before measuring the signal. If you do not use  
Relation function, add 20 digits for accuracy purposes.  
9
10 10 A continuous and additional 0.5% to specified accuracy when measuring a signal greater than 10 A~20 A for 30 seconds  
maximum. After measuring current for > 10 A, to cool down the meter for twice the measuring time you applied before low  
current measurement.  
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11 The current can be measuring from 2.5 A to 10 A continuous, and the additional of 0.5% to specified accuracy as measure  
the signal greater than 10 A~20 A for 30 seconds maximum. After measured current for > 10 A, to cool down the meter for  
2 times of measuring time you applied before low current measurement.  
12 For signal frequency greater than 1 kHz, additional 0.1% per kHz to be added to accuracy.  
13 Ensure that the ambient temperature is stable within 1ºC. Make sure that the multimeter is placed in a controlled  
environment for at least 1 hour. Keep the multimeter away from any ventilation exit. Do not touch the thermocouple test  
lead after connecting it to the calibrator. Allow the connection to stabilize for at least another 15 minutes before performing  
the measurement.  
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Performance Tests and Calibration  
Unsecuring the instrument for calibration  
Before you can adjust the instrument, you must unsecure it  
by entering the correct security code. The security code is  
set to 1234 when the instrument is shipped from the  
factory. The security code is stored in non-volatile memory,  
and does not change when power is off.  
To Unsecure the Instrument from the Front Panel  
4 Turn the rotary switch to  
.
5 Press  
and  
button simultaneously to enter  
the Calibration Security Code entry mode.  
6 The primary display shows 5555 and the secondary  
display show SECUr.  
7 Use the editing keys  
and  
to step each  
character in the code.  
Use the  
and  
to select each character.  
8 Press  
(Save) when done.  
9 If the correct security code is entered, the secondary  
display will show PASS.  
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7
To change the instrument calibration security code from the front  
panel  
1 When the multimeter is in the unsecured mode, press  
for more than 1 second to enter the Calibration  
Security Code setting mode.  
2 The factory default calibration security code 1234 will be  
displayed on the primary display.  
3 Use the editing keys  
and  
to step each  
character in the code.  
4 Use the  
and  
to change each character in  
the code.  
5 Press  
(Save) to store the new calibration security  
code.  
6 If the new calibration security code has been successfully  
stored, the secondary display will show PASS.  
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Performance Tests and Calibration  
To unsecure the instrument without the security code  
To unsecure the instrument without the correct security  
code, follow the steps below.  
If you do not have a record of the security code, you can try 1234 (the fac-  
tory default code) using the front panel.  
NOTE  
1 Record the last 4 digits of the multimeter’s serial number.  
2 Turn the rotary switch to  
.
3 Press and  
simultaneously to enter the  
Calibration Security Code entry mode.  
4 The primary display shows 5555 and the secondary  
display shows SECUr.  
5 Press  
for more than 1 second to enter the Set  
Default Security Code mode. The secondary display shows  
SEr.no and the primary display shows 5555.  
6 Use the editing keys  
and  
to step each  
character in the code.  
Use  
and  
to select each character.  
7 Set the code, same as the last 4 digits of the instrument’s  
serial number.  
8 Press  
(Save) to confirm the entry.  
9 If the 4 digits entered are correct, the secondary display  
will show PASS.  
130  
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Performance Tests and Calibration  
7
Now you can use 1234 as the security code. If you want to  
enter a new security code, see “To change the instrument  
calibration security code from the front panel” on page 129.  
Make sure you record the new security code.  
Calibration process  
To complete a full instrument calibration use following  
general procedures:  
1 Read “Test Considerations” on page 118.  
2 Perform the verification tests to characterize the  
instrument (incoming data).  
3 Unsecure the instrument for calibration (see “Calibration  
Security” on page 119).  
4 Perform the adjustment procedures (see “Adjustments  
Consideration” on page 133).  
5 Secure the instrument against calibration.  
6 Note the new security code and calibration count in the  
instrument's maintenance records.  
Make sure to quit the Adjustment Mode before turning off the instrument.  
NOTE  
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Performance Tests and Calibration  
Using the front panel for adjustments  
This section describes the procedures to perform  
adjustments from the front panel.  
Selecting the Adjustment Mode  
To unsecure the instrument, see “Unsecuring the instrument  
for calibration” on page 128 or “To unsecure the instrument  
without the security code” on page 130. Once unsecured, the  
reference value will be indicated on the primary display.  
Entering Adjustment Values  
Use the following adjustment procedure to enter an input  
calibration value from the front panel:  
1 Use the edit keys  
and  
to select each digit in  
the primary display.  
2 Use the  
through the digits 0 through 9.  
3 Press when done to start calibration.  
and the  
arrow keys to advance  
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7
Adjustments Consideration  
You will need a test input cable, a connectors set, and a  
Shorting Plug to adjust the instrument.  
After each adjustment, the secondary display briefly shows PASS. If the  
calibration fails, the handheld multimeter sounds a beep, and an error  
NOTE  
number is shown in the secondary display. Calibration error messages are  
described on page 143. In the event of a calibration failure, correct the  
problem and repeat the procedure.  
Adjustments for each function should be performed only in  
the order shown below.  
1 Allow the instrument to warm up and stabilize for 5  
minutes before performing the adjustments.  
2 Ensure that during the adjustments, the low battery  
indicator does not appear. Replace the batteries as soon  
as possible to avoid false reading.  
3 Consider the thermal effects as you are connecting test  
leads to the calibrator and handheld multimeter. It is  
recommended to wait for one minute before you begin the  
calibration after connecting the test leads.  
4 During ambient temperature adjustment, be sure to turn  
on the instrument for at least 1 hour with the K-type  
thermocouple connected between the instrument and the  
calibration source.  
Never turn off the instrument during an adjustment. This may delete the  
calibration memory for the present function.  
CAUTION  
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Performance Tests and Calibration  
Valid adjustment input values  
Adjustment can be accomplished using the following input  
values below.  
Table 6-3 Valid adjustment input values  
Function  
Range  
Valid Amplitude Input Values  
0.9 to 1.1 x Full Scale  
5 V, 50 V, 500 V, 1000 V  
0.9 to 1.1 x Full Scale  
5 V, 50 V, 500 V, 1000 V  
V
(for U1251A)  
0.9 to 1.1 x Full Scale  
0.9 to 1.1 x Full Scale  
0.9 to 1.1 x Full Scale  
0.9 to 1.1 x Full Scale  
0.9 to 1.1 x Full Scale  
5 V, 50 V ,500 V, 1000 V  
50 mV, 500 mV, 1000 mV  
500 µA, 5000 µA  
(for U1252A)  
50 mA, 440 mA, 5 A, 10 A  
Ω
500 Ω, 5 kΩ, 50 kΩ,500 kΩ, 5 MΩ,  
50 MΩ  
/ TEMP  
10 nF, 100 nF, 1000 nF, 10 µF, 100 µF,  
Make sure to provide 0 °C with ambient  
1000 µF, 10 mF / 0 °C  
compensation  
134  
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Performance Tests and Calibration  
7
Adjustment procedure  
Review the sections “Test Considerations” on page 118 and  
“Adjustments Consideration” on page 133 before proceeding  
with this procedure.  
1 Turn the rotary switch to “Test Function” position as  
shown in the adjustment table.  
2 After unsecuring the instrument, the instrument goes into  
the adjustment mode. (See “Unsecuring the instrument for  
calibration” on page 128)  
The instrument will be in the adjustment mode, unless you Press SHIFT  
NOTE  
and  
simultaneously to exit the adjustment mode.  
3 The primary display will show the reference value of the  
Cal Item.  
4 Configure each Cal Item.  
5 Use the  
Cal Range.  
and the  
arrow keys to select the  
6 Apply the input signal shown in the Input column of the  
table. The bar graph will display the Input reading. There  
is no bar graph display for temperature adjustment.  
Always complete the tests in the same order as shown in the appropriate  
table.  
NOTE  
7 Enter the actual applied input (see “Entering Adjustment  
Values” on page 132).  
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Performance Tests and Calibration  
8 Press  
to start the adjustment. The CAL flashes in  
the secondary display to indicate that the calibration is in  
progress.  
For an adjustment that is successful, the secondary  
display will briefly show PASS. An adjustment failure is  
indicated by a long beep and a calibration error number  
appears in the secondary display. The primary display  
remains at the current Cal Item. Check the input value,  
range, function, and entered adjustment value to fix the  
problem. Repeat the adjustment procedure.  
9 Repeat steps 1 through 8 for each adjustment point.  
10 Verify the adjustments using the “Performance Verification  
Tests” on page 120 and Table 6-2.  
136  
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7
Table 6-4 Adjustment table  
Cal Item  
Step  
Test Function  
Cal Range  
Input  
U1251A  
U1252A  
1
Turn the rotary switch to the  
V position  
5 V  
0.3 V,1 kHz  
0.3000 V  
0.3000 V  
3 V, 1 kHz  
3.0000 V  
N/A  
3.0000 V  
3.0000 V  
03.000 V  
30.000 V  
30.000 V  
030.00 V  
300.00 V  
300.00 V  
0030.0 V  
0300.0 V  
0300.0 V  
SHort  
3 V, 50 kHz  
3 V, 1 kHz  
50 V  
03.000 V  
30.000 V  
N/A  
30 V, 1 kHz  
30 V, 50 kHz  
30 V,1 kHz  
300 V,1 kHz  
300 V, 50 kHz  
30 V, 1 kHz  
300 V, 1 kHz  
300 V, 50 kHz  
500 V  
1000 V  
Short  
030.00 V  
300.00 V  
N/A  
0030.0 V  
0300.0 V  
N/A  
2
Turn the rotary switch to  
Dual Banana Plug  
with copper wire  
short between 2  
terminals  
SHort  
V position (for model U1252A),  
to  
V position (for model  
U1251A)  
5 V  
3 V  
3.0000 V  
30.000 V  
300.00 V  
1000.0 V  
3.0000 V  
30.000 V  
300.00 V  
1000.0 V  
50 V  
30 V  
500 V  
1000 V  
300 V  
1000 V  
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Performance Tests and Calibration  
Cal Item  
U1252A  
Step  
Test Function  
Cal Range  
Input  
U1251A  
3
Press  
button to go to the  
V mode  
5 V  
0.3 V, 1 kHz  
N/A  
0.3000 V  
3 V, 1 kHz  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
SHort  
3.0000 V  
3.0000 V  
03.000 V  
30.000 V  
30.000 V  
030.00 V  
300.00 V  
300.00 V  
0030.0 V  
0300.0 V  
0300.0 V  
SHort  
3 V, 50 kHz  
3 V, 1 kHz  
50 V  
30 V, 1 kHz  
30 V, 50 kHz  
30 V, 1 kHz  
300 V, 1 kHz  
300 V, 50 kHz  
30 V, 1 kHz  
300 V, 1 kHz  
300 V, 50 kHz  
500 V  
1000 V  
Short  
4
Turn the rotary switch to the  
mV position  
Dual banana plug  
with copper wire  
short between 2  
terminals  
50 mV  
30 mV  
30.000 mV  
300.00 mV  
1000.0 mV  
30.000 mV  
300.00 mV  
1000.0 mV  
500 mV  
1000 mV  
300 mV  
1000 mV  
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7
Cal Item  
Step  
Test Function  
Cal Range  
Input  
U1251A  
U1252A  
5
Press  
button to go to the  
mV mode  
50 mV  
3 mV, 1 kHz  
03.000 mV  
03.000 mV  
30 mV, 1 kHz  
30.000 mV  
N/A  
30.000 mV  
30.000 mV  
030.00 mV  
300.00 mV  
300.00 mV  
0030.0 mV  
1000.0 mV  
1000.0 mV  
SHort  
30 mV, 50 kHz  
30 mV, 1 kHz  
500 mV  
1000 mV  
Short  
030.00 mV  
300.00 mV  
N/A  
300 mV, 1 kHz  
300 mV, 50 kHz  
30 mV, 1 kHz  
0030.0 mV  
1000.0 mV  
N/A  
1000 mV, 1 kHz  
1000 mV, 50 kHz  
6
Turn the rotary switch to the W  
Dual Banana  
Plug with copper  
wire short  
SHort  
position  
between 2  
terminals  
50 MW  
Input terminal  
open (Remove  
any test leads  
and Short Plugs  
from the input  
terminal)  
oPEn  
oPEn  
10 MW  
3 MW  
300 kW  
30 kW  
3k W  
10.000 MW  
3.0000 MW  
300.00 kW  
30.000 kW  
3.0000 kW  
300.00 W  
10.000 MW  
3.0000 MW  
300.00 kW  
30.000 kW  
3.0000 kW  
300.00 W  
5 MW  
500 kW  
50 kW  
5 kW  
500 W  
300 W  
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Performance Tests and Calibration  
Cal Item  
U1252A  
Step  
Test Function  
Cal Range  
Input  
U1251A  
7
Turn the rotary switch to the  
Open  
Input terminal  
oPEn  
oPEn  
TEMP/  
position  
open (Remove any  
test leads and  
Short Plugs from  
the input terminal)  
10 nF  
3 nF  
03.000 nF  
10.000 nF  
010.00 nF  
100.00 nF  
0100.0 nF  
1000.0 nF  
10.000 μF  
100.00 μF  
1000.0 μF  
10.000 mF  
0000.0 ºC  
03.000 nF  
10.000 nF  
010.00 nF  
100.00 nF  
0100.0 nF  
1000.0 nF  
10.000 μF  
100.00 μF  
1000.0 μF  
10.000 mF  
0000.0 ºC  
10 nF  
100 nF  
1000 nF  
10 nF  
100 nF  
100 nF  
1000 nF  
10 μF  
100 μF  
1000 μF  
10 mF  
0 ºC  
10 μF  
100 μF  
1000 μF  
10 mF  
N/A  
8
9
Press  
TEMP mode  
button to go to  
Note: Ensure the multimeter is turned on and stabilized for at least 60 minutes, with the K-type thermocouple  
connected between the multimeter and the calibrator output terminal  
Turn the rotary swich to the  
OPEN  
Input terminal  
oPEn  
oPEn  
mA position  
open (Remove any  
test leads and  
Short Plugs from  
the input terminal)  
500 μA  
300 μA  
300.00 μA  
3000.0 μA  
300.00 μA  
3000.0 μA  
5000 μA  
3000 μA  
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10  
11  
Press  
button to go to  
mA mode  
500 μA  
5000 μA  
Open  
30 μA,1 kHz  
030.00 μA  
300.00 μA  
0300.0 μA  
3000.0 μA  
oPEn  
030.00 μA  
300.00 μA  
0300.0 μA  
3000.0 μA  
oPEn  
300 μA,1 kHz  
300 μA,1 kHz  
3000 μA, 1 kHz  
Turn the Rotary Switch to the  
mA.A position  
Input terminal  
open (Remove any  
test leads and  
Short Plugs from  
the input terminal)  
50 mA  
30 mA  
30.000 mA  
300.00 mA  
30.000 mA  
300.00 mA  
440 mA  
300 mA  
Move the test lead from uA.mA and COM terminal to A and COM terminal  
Caution: Connect calibrator to hanheld multimeter's A and COM terminal before applying 3A and 10A  
5 A  
3 A  
3.0000 A  
10.000 A  
3.0000 A  
10.000 A  
10 A  
10 A  
Move the test lead from A and COM terminal to uA.mA and COM terminal  
12  
Press  
button to go to  
mA mode  
50 mA  
3 mA, 1 kHz  
03.000 mA  
03.000 mA  
30 mA, 1 kHz  
30 mA, 1 kHz  
300 mA, 1 kHz  
30.000 mA  
030.00 mA  
300.00 mA  
30.000 mA  
030.00 mA  
300.00 mA  
440 mA  
Move the test lead from uA.mA and COM terminal to A and COM terminal  
Caution: Connect calibrator to hanheld multimeter's A and COM terminal before applying 3A and 10A  
13  
Press  
button to go to  
A mode  
5 A  
0.3 A, 1 kHz  
0.3000 A  
0.3000 A  
3 A, 1 kHz  
3 A, 1 kHz  
10 A, 1 kHz  
3.0000 A  
3.0000 A  
10.000 A  
3.0000 A  
3.0000 A  
10.000 A  
10 A  
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Performance Tests and Calibration  
Finishing the adjustment  
1 Remove all the shorting plugs and connectors from the  
instrument.  
2 Record the new Calibration Count.  
3 Press  
and  
simultaneously to exit the  
Adjustment Mode. Power off and on again. The instrument  
will then be secured.  
To read the calibration count  
You can query the instrument to determine how many  
calibrations have been performed.  
Your instrument was calibrated before it left the factory.  
NOTE  
When you receive your instrument, read the count to  
determine its initial value.  
The count value increases by one for each calibration point,  
and a complete calibration will increase the value by many  
counts. The calibration count increments up to a maximum  
of 65535 after which it is set at 0. The calibration count can  
be read from the front panel after the instrument has been  
unsecured. Use the following procedure to read the  
calibration count from the front panel.  
1 Press  
shows the calibration count.  
2 Take note of the count.  
Adjustment Mode. The primary display  
3 Press  
again to exit the calibration count mode.  
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7
Calibration errors  
The following errors indicate failures that may occur during  
a calibration.  
Number  
200  
Recommended Accuracy Requirements  
Calibration error: calibration mode is secured  
Calibration error: secure code invalid  
Calibration error: serial number code invalid  
Calibration error: calibration aborted  
Calibration error: value out of range  
002  
003  
004  
005  
006  
Calibration error: signal measurement out of range  
Calibration error: frequency out of range  
EEPROM write failure  
007  
008  
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Performance Tests and Calibration  
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User’s and Service Guide  
7
Specifications  
Product Characteristics 146  
Measurement Category 149  
Measurement category definition 149  
Specification Assumptions 150  
Electrical Specifications 151  
DC Specifications 151  
AC Specifications 153  
AC+DC Specifications for U1252A 155  
Capacitance Specifications 156  
Temperature Specifications 156  
Frequency Specifications 157  
Duty Cycle and Pulse Width Specifications 157  
Frequency Sensitivity Specifications 158  
Peak Hold Specifications 159  
Frequency Counter Specifications for U1252A 160  
Square Wave Output for U1252A 161  
Operating Specifications 162  
Display update rate (approximate) 162  
Input impedance 163  
This chapter lists the product characteristics, specification  
assumptions and the specifications of the U1251A and  
U1252A digital multimeters.  
Agilent Technologies  
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8
Specifications  
Product Characteristics  
POWER SUPPLY  
Battery type:  
•
•
•
•
9 V size Ni-MH rechargeable battery, 7.2 V nominal voltage  
9 V size Ni-MH rechargeable battery, 8.4 V nominal voltage  
9 V Alkaline battery (ANSI/NEDA 1604A or IEC 6LR61)  
9 V Carbon-zinc battery (ANSI/NEDA 1604D or IEC6F22)  
Battery life:  
•
8 hours typical (based on a fully charged Ni-MH 300 mAH battery for DC  
voltage measurement)  
•
14 hours typical (based on a new 9 V Alkaline battery for DC voltage  
measurement)  
Charge time (U1252A only):  
•
Less than 220 minutes in an environment of 10 °C to 30 °C. if the battery has  
been deep-discharged, a prolonged charging time is required in order for the  
battery to return to full capacity  
POWER CONSUMPTION  
•
•
105 mVA / 420 mVA (with backlight usage) maximum (U1251A)  
165 mVA / 480 mVA (with backlight usage) maximum (U1252A)  
DISPLAY  
•
Both primary and secondary displays are 5-digit liquit crystal display (LCD)  
with maximum reading of 50,000 counts  
Automatic polarity indication  
•
OPERATING ENVIRONMENT  
•
•
Temperature: Full accuracy from –20 °C to 55 °C.  
Humidity: Full accuracy up to 80% RH (relative humidity) for temperatures up  
to 35°C, decreasing linearly to 50% RH at 55 °C.  
Altitude:  
•
•
•
0 to 2000 meters complying with IEC 61010-1 2nd Edition CAT III, 1000 V/  
CAT IV, 600 V.  
Pollution degree II  
STORAGE COMPLIANCE  
–40 °C to 70 °C with battery removed  
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Specifications  
8
SAFETY COMPLIANCE  
•
•
•
EN/IEC 61010-1:2001  
ANSI/UL 61010-1:2004  
CAN/CSA-C22.2 No. 61010-1-04  
MEASUREMENT CATEGORY  
CAT III 1000 V/CAT IV 600 V Overvoltage Protection  
EMC COMPLIANCE  
•
•
•
•
Certified to IEC61326-1:2005 / EN61326-1:2006  
CISPR 11:2003 / EN 55011:2007 Group 1 Class A  
Canada: ICES-001:2004  
Austrailia/New Zealand; AS/NZS CISPR11:2004  
SHOCK AND VIBRATION  
Tested to IEC/EN 60068-2  
TEMPERATURE COEFFICIENT  
0.15 × (specified accuracy) / °C (from –20 °C to 18 °C, or 28 °C to 55 °C)  
COMMON MODE REJECTION RATIO (CMRR)  
> 90 dB at DC, 50/60 Hz 0.1% (1 kΩ unbalanced)  
NORMAL MODE REJECTION RATION (NMRR)  
> 60 dB at 50/60 Hz 0.1%  
DIMENSIONS (W × H × D)  
94.4 × 203.5 × 59 mm  
WEIGHT  
•
•
504 5 grams with battery (U1251A)  
527 5 grams with battery (U1252A)  
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Specifications  
WARRANTY  
Please refer to http://www.agilent.com/go/warranty_terms  
•
•
Three years for the product  
Three months for the product's standard accessories, unless otherwise  
specified  
Please take note that for the product, the warranty does not cover:  
•
•
•
Damage from contamination  
Normal wear and tear of mechanical components  
Manuals, fuses, and standard disposable batteries  
CALIBRATION CYCLE  
One year  
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Specifications  
8
Measurement Category  
The Agilent U1251A and U1252A Handheld Digital  
Multimeter has a safety rating of CAT III 1000 V/ CAT IV,  
600 V.  
Measurement category definition  
Measurement CAT I are measurements performed on circuits  
which are not directly connected to the AC mains. For  
example, measurements on circuits not derived from the AC  
mains or specially protected (internal) mains-derived  
circuits.  
Measurement CAT II are measurements performed on circuits  
that are directly connected to a low voltage installation. For  
example, measurements on household appliances, portable  
tools and other similar equipment.  
Measurement CAT III are measurements performed on  
building installations. For example, measurements on  
distribution boards, circuit-breakers, wiring (including  
cables), bus-bars, junction boxes, switches, socket outlets  
within the fixed installation, equipment for industrial use  
and equipment that is permanently connected to the fixed  
installation such as stationary motors.  
Measurement CAT IV are measurements performed at the  
source of the low-voltage installation. For example,  
measurements on electricity meters, primary over-current  
protection devices and ripple control units.  
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Specifications  
Specification Assumptions  
• The DC specifications are defined for measurements  
which are taken after at least 1 minute of warm-up time.  
• The AC and AC+DC specifications are defined for  
measurements of sine wave and are taken after at least 1  
minute of warm-up time.  
• The accuracy of the multimeter may be affected when  
making measurements in an environment where  
electromagnetic interferences or significant electrostatic  
charges are present.  
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Electrical Specifications  
DC Specifications  
Table 7-1 DC Accuracy (% of reading + Number of Least Significant Digit)  
Accuracy  
Test Current/  
Function  
Range  
Resolution  
0.001 mV  
0.01 mV  
0.1 mV  
0.0001 V  
0.001 V  
0.01 V  
Burden Voltage  
U1251A  
0.05 + 50  
U1252A  
0.05 + 50  
[2]  
[2]  
50.000 mV  
500.00 mV  
1000.0 mV  
5.0000 V  
50.000 V  
500.00 V  
1000.0 V  
-
-
-
-
-
-
-
[1]  
Voltage  
0.025 + 5  
0.03 + 5  
0.03 + 5  
0.1 V  
Notes for DC voltage specifications:  
1
2
Input impedance: >1GΩ for 50 mV to 1000 mV ranges. For U1251A, input impedance is 10 MΩ (nominal) for 5 V to 1000 V  
ranges. For U1252A, input impedance is 10 MΩ (nominal) in parallel with 1.1 MΩ at dual display.  
The accuracy could be 0.05 % +10 for U1251A and 0.05 % + 5 for U1252A. Always use the Null function to zero out the  
thermal effect before measuring the signal.  
Accuracy  
Test Current/  
Function  
Range  
500.00 Ω  
5.0000 kΩ  
50.000 kΩ  
500.00 kΩ  
5.0000 MΩ  
Resolution  
0.01 Ω  
0.0001 kΩ  
0.001 kΩ  
0.01 kΩ  
Burden Voltage  
U1251A  
0.08 + 10  
U1252A  
0.05 + 10  
[3]  
[3]  
1.04 mA  
416 µA  
41.2 µA  
4.12 µA  
375 nA  
187 nA  
0.08 + 5  
0.05 + 5  
0.0001 MΩ  
0.001 MΩ  
0.2 + 5  
1 + 10  
0.15 + 5  
1 + 5  
Resistance  
[4]  
50.000 MΩ  
3 + 10 < 200MΩ/  
[4]  
500.00 MΩ  
0.01 MΩ  
187 nA  
187 nA  
-
8 + 10 > 200MΩ  
[5]  
500.00 nS  
Notes for resistance specifications:  
0.01 nS  
1 + 20  
1 + 10  
3
The accuracy of 500 Ω and 5 kΩ is specified after Null function, which is used to subtract the test lead resistance and the  
thermal effect.  
4
5
For the range of 50/500 MΩ, the R.H. is specified for < 60 %.  
The accuracy is specified for < 50 nS and after Null function with open test lead.  
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Specifications  
Table 7-1 DC Accuracy (% of reading + Number of Least Significant Digit) (continued)  
Accuracy  
Test Current/  
Function  
Range  
Resolution  
0.01 µA  
Burden Voltage  
U1251A  
U1252A  
0.05 + 5  
0.05 + 5  
0.15 + 5  
0.15 + 5  
[6]  
[6]  
[6]  
[6]  
[6]  
500.00 µA  
5000.0 µA  
50.000 mA  
440.00 mA  
5.0000 A  
0.06 V  
0.6 V  
0.09 V  
0.9 V  
0.2 V  
0.4 V  
0.1 + 5  
0.1 + 5  
0.2 + 5  
0.2 + 5  
[6]  
[6]  
[6]  
0.1 µA  
0.001 mA  
0.01 mA  
0.0001 A  
0.001 A  
Current  
0.3 + 10  
0.3 + 10  
0.3 + 10  
0.3 + 5  
[7]  
10.000 A  
Notes for current specifications:  
6
Always use the Null function to zero out thermal effect with open test lead before measuring the signal. If the Null  
function is not used, add 20 counts to the specified accuracy. Thermal effect could occur due to the following:  
•
Wrong operation – where the resistance, diode or mV measurement function is used to measure high voltage signals  
within the range of 50 V to 1000V  
•
•
After battery-charging is complete.  
After measuring a current greater than 440 mA. Thus we recommend that the meter be left to cool down for twice the  
length of measurement time used.  
7
Current can be measured up to 10 A continuously. An additional 0.5 % needs to be added to the specified accuracy if the  
signal measured is in the range of 10 A to 20 A 30 seconds maximum. After measuring current > 10 A, leave the meter to  
cool down (in switched OFF state) for twice the length of measuring time used before application of low current  
measurement.  
Accuracy  
Test Current/  
Function  
Range  
Resolution  
Burden Voltage  
U1251A  
U1252A  
[8]  
Diode  
-
0.1 mV  
1.04 mA  
0.05 + 5  
Notes for diode specifications:  
8
Maximum open voltage: < + 4.2 V.  
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AC Specifications  
AC specifications for U1251A  
Table 7-2 U1251A accuracy specifications (% of reading + number of LSD) for true RMS AC voltage  
Frequency  
Function  
Range  
Resolution  
0.001 mV  
0.01 mV  
0.1 mV  
0.0001 V  
0.001 V  
0.01 V  
30 Hz to 45 Hz  
1 + 60  
45 Hz to 1 kHz  
0.6 + 40  
0.6 + 25  
0.6 + 25  
0.6 + 25  
0.6 + 25  
0.6 + 25  
0.6 + 40  
1 kHz to 10 kHz  
1.0 + 40  
10 kHz to 30 kHz  
1.6 + 60  
50.000 mV  
500.00 mV  
1000.0 mV  
5.0000 V  
50.000 V  
500.00 V  
1000.0 V  
1 + 60  
1 + 60  
1 + 60  
1 + 60  
1 + 60  
1 + 60  
1.0 + 40  
1.0 + 25  
1.0 + 25  
1.0 + 25  
1.0 + 25  
1.0 + 40  
1.6 + 60  
1.6 + 40  
1.6 + 40  
[1]  
Voltage  
1.6 + 40  
[2]  
1.6 + 40  
0.1 V  
-
Notes for U1251A AC voltage specifications:  
1
2
Input impedance: > 1GHz for 50 mV to 1000 mV. Input impedance is 1.1 MΩ (nominal) with <100 pF for 5 V to 1000 V  
ranges.  
The input signal is lower than the product of 20,000,000 V-Hz (product of voltage and frequency).  
Table 7-3 U1251A accuracy specifications (% of reading + number of LSD) for true RMS AC current  
Frequency  
Function  
Range  
Resolution  
0.01 µA  
30 Hz to 45 Hz  
1.5 + 50  
45 Hz to 2 kHz  
0.8 + 20  
2 kHz to 20 kHz  
3 + 80  
[1]  
500.00 µA  
5000.0 µA  
50.000 mA  
440.00 mA  
5.0000 A  
0.1 µA  
1.5 + 40  
1.5 + 40  
1.5 + 40  
0.8 + 20  
0.8 + 20  
0.8 + 20  
0.8 + 20  
3 + 60  
3 + 60  
3 + 60  
3 + 60  
Current  
0.001 mA  
0.01 mA  
0.0001 A  
0.001 A  
[3]  
2 + 40  
[2]  
[3]  
10.000 A  
2 + 40  
0.8 + 20  
< 3 A/5 kHz  
Notes for U1251A AC current specifications:  
1
2
Input current > 35 µArms.  
Current can be measured from 2.5 A up to 10 A continuously. Add 0.5% to the specified accuracy if the signal measured is  
in the range of 10 A to 20 A and for a period of up to 30 seconds. After measuring current > 10 A, leave the meter to cool  
down for a period that is twice the measuring time used before application of low current measurement.  
Input current < 3 Arms.  
3
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Specifications  
AC specifications for U1252A  
Table 7-4 U1252A accuracy specifications (% of reading + number of LSD) for true RMS AC voltage  
Frequency  
20 Hz –  
45 Hz  
45 Hz –  
1 kHz  
1 kHz –  
10 kHz  
10 kHz –  
20 kHz  
20 kHz –  
100 kHz  
[1]  
Function  
Range  
Resolution  
0.001 mV  
0.01 mV  
0.1 mV  
0.0001 V  
0.001 V  
0.01 V  
50.000 mV  
500.00 mV  
1000.0 mV  
5.0000 V  
50.000 V  
500.00 V  
1000.0 V  
1.5 + 60  
1.5 + 60  
1.5 + 60  
1.5 + 60  
1.5 + 60  
1.5 + 60  
1.5 + 60  
0.4 + 40  
0.4 + 25  
0.4 + 25  
0.4 + 25  
0.4 + 25  
0.4 + 25  
0.4 + 40  
0.7 + 40  
0.4 + 25  
0.4 + 25  
0.4 + 25  
0.4 + 25  
0.4 + 25  
0.4 + 40  
0.75 + 40  
0.75 + 40  
0.75 + 40  
0.75 + 40  
0.75 + 40  
1.5 + 40  
3.5 + 120  
3.5 +120  
3.5 + 120  
3.5 + 120  
3.5 + 120  
[2]  
Voltage  
[3]  
3.5 + 120  
-
[3]  
0.1 V  
1.5 + 40  
Notes for U1252A AC voltage specifications:  
1
2
The additional error to be added as frequency > 20 kHz and signal input <10 %of range: 3 counts of LSD per kHz.  
Input impedance: > 1GHz for 50 mV to 1000 mV. Input impedance is 1.1 MΩ (nominal) with <100 pF for 5 V to 1000 V  
ranges.  
3
The input signal is lower than the product of 20,000,000 V-Hz (product of voltage and frequency).  
Table 7-5 U1252A accuracy specifications (% of reading + number of LSD) for true RMS AC current  
Frequency  
20 kHz –  
100 kHz  
20 Hz – 45 Hz 45 Hz – 1 kHz 1 kHz – 20 kHz  
[1]  
Function  
Range  
Resolution  
0.01 µA  
[2]  
500.00 µA  
1.0 + 20  
1.0 + 20  
1.0 + 20  
1.0 + 20  
0.7 + 20  
0.7 + 20  
0.7 + 20  
0.7 + 20  
0.7 + 20  
0.7 + 20  
0.75 + 20  
0.75 + 20  
0.75 + 20  
1.5 + 20  
3 + 60  
5 + 80  
5 + 80  
5 + 80  
5 + 80  
5000.0 µA  
50.000 mA  
440.00 mA  
5.0000 A  
0.1 µA  
Current  
0.001 mA  
0.01 mA  
0.0001 A  
0.001 A  
[4]  
1.5 + 20  
1.5 + 20  
-
[3]  
[4]  
10.000 A  
< 3 A/5 kHz  
Notes for U1252B AC current specifications:  
1
2
3
The additional error to be added as frequency > 20 kHz and signal input< 10 % of range: 3 counts of LSD per kHz.  
Input current > 35 µArms.  
Current can be measured from 2.5 A up to 10 A continuously. Add 0.5% to the specified accuracy if the signal measured is  
in the range of 10 A to 20 A and for a period of up to 30 seconds. After measuring current > 10 A, leave the meter to cool  
down for a period that is twice the measuring time used before application of low current measurement.  
Input current < 3 Arms.  
4
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AC+DC Specifications for U1252A  
Table 7-6 U1252A true RMS ac+dc voltage specifications  
Frequency  
1 kHz –  
10 kHz  
0.7 + 60  
0.4 + 30  
0.4 + 30  
0.4 + 30  
0.4 + 30  
0.4 + 30  
0.4 + 45  
30 Hz –  
45 Hz  
45 Hz –  
1 kHz  
10 kHz –  
20 kHz  
20kHz –  
100kHz  
[1]  
Function  
Range  
Resolution  
0.001 mV  
0.01 mV  
0.1 mV  
0.0001 V  
0.001 V  
0.01 V  
50.000 mV  
500.00 mV  
1000.0 mV  
5.0000 V  
50.000 V  
500.00 V  
1000.0 V  
1.5 + 80  
1.5 + 65  
1.5 + 65  
1.5 + 65  
1.5 + 65  
1.5 + 65  
1.5 + 65  
0.4 + 60  
0.4 + 30  
0.4 + 30  
0.4 + 30  
0.4 + 30  
0.4 + 30  
0.4 + 45  
0.8 + 60  
0.8 + 45  
0.8 + 45  
0.8 + 45  
0.8 + 45  
1.5 + 45  
3.5 + 220  
3.5 + 125  
3.5 + 125  
3.5 + 125  
3.5 + 125  
[2]  
Voltage  
[3]  
3.5 + 125  
-
[3]  
0.1 V  
1.5 + 45  
Notes for U1252A AC +DC voltage specifications:  
1
2
The additional error to be added as frequency > 20 kHz and signal input <10 %of range: 3 counts of LSD per kHz.  
Input impedance: > 1 GW for 50 mV to 1000 mV. Input impedance is 1.1 MΩ (nominal) with <100 pF for 5 V to 1000 V  
ranges.  
3
The input signal is lower than the product of 20,000,000 V-Hz (product of voltage and frequency).  
Table 7-7 U1252A true RMS ac+dc current specifications  
Frequency  
45 Hz – 1 kHz  
0.8 + 25  
Function  
Range  
Resolution  
0.01 µA  
30 Hz – 45 Hz  
1.1 + 25  
1 kHz – 20 kHz  
0.8 + 25  
[1]  
500.00 µA  
5000.0 µA  
50.000 mA  
440.00 mA  
5.0000 A  
0.1 µA  
1.1 + 25  
1.2 + 25  
1.2 + 25  
0.8 + 25  
0.9 + 25  
0.9 + 25  
0.9 + 30  
0.8 + 25  
0.9 + 25  
0.9 + 25  
3.3 + 70  
0.001 mA  
0.01 mA  
0.0001 A  
0.001 A  
Current  
[3]  
1.8 + 30  
[2]  
[3]  
10.000 A  
1.8 + 30  
0.9 + 25  
< 3 A/5 kHz  
Notes for U1252A AC +DC current specifications:  
1
2
Input current > 35 µArms.  
Current can be measured from 2.5 A up to 10 A continuously. Add 0.5% to the specified accuracy if the signal measured is  
in the range of 10 A to 20 A and for a period of up to 30 seconds. After measuring current > 10 A, leave the meter to cool  
down for a period that is twice the measuring time used before application of low current measurement.  
Input current < 3 Arms.  
3
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Specifications  
Capacitance Specifications  
Table 7-8 Capacitance specifications  
Accuracy  
(% of reading +  
Offset Error)  
1 % + 8  
Display update rate  
(approx)  
Function  
Range  
Resolution  
10.000 nF  
100.00 nF  
1000.0 nF  
10.000 µF  
100.00 µF  
1000.0 µF  
10.000 mF  
100.00 mF  
0.001 nF  
0.01 nF  
0.1 nF  
0.001 µF  
0.01 µF  
0.1 µF  
4 times/sec.  
Capacitance  
1 % + 5  
1 time/sec.  
0.1 times/sec.  
0.01 times/sec.  
0.001 mF  
0.01 mF  
3 % + 10  
Temperature Specifications  
Table 7-9 Temperature specifications  
Accuracy  
Thermocouple  
Range  
Resolution  
(% of reading + No. of  
Least Significant Digit)  
0.3 % + 3 °C/  
Type  
–200 – 1372 °C/  
0.1 °C/  
K
–328 – 2502 °F  
0.1 °F  
0.3 % + 6 °F  
–210 – 1200 °C/  
0.1 °C/  
0.3 % + 3 °C/  
[2]  
J
–346 – 2192 °F  
0.1 °F  
0.3 % + 6 °F  
Notes for temperature specifications:  
1
Accuracy of specifications is subject to the following conditions:  
•
The accuracy does not include the tolerance of the thermocouple probe. The thermal sensor plugged into the meter  
should be placed in the operating environment for at least an hour.  
•
Use the Null function to reduce the thermal effect. Before using the NULL function, set the meter to no ambient  
compensation (  
) mode and keep the thermocouple probe as close to the meter as possible, avoiding contact with  
any surface that has a different temperature from the ambient temperature.  
•
When measuring temperature with respect to any temperature calibrator, try to set both the calibrator and the meter  
with an external reference (without internal ambient compensation). If both the calibrator and the meter are set with  
internal reference (with internal ambient compensation), deviation may show between the readings of the calibrator  
and the meter, due to differences in ambient compensation between the calibrator and the meter.  
2
This thermocouple type is only available for the U1252A.  
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Frequency Specifications  
Table 7-10 Frequency specifications  
Accuracy  
Range  
Resolution  
(% of reading + No. of  
Least Significant Digit)  
Min. Input Frequency  
99.999 Hz  
999.99 Hz  
9.9999 kHz  
99.999 kHz  
999.99 kHz  
0.001 Hz  
0.01 Hz  
0.0001 kHz  
0.001 kHz  
0.01 kHz  
0.02% + 3  
< 600 kHz  
1 Hz  
Notes for frequency specifications:  
1
The multimeter will automatically select the most appropriate range when making frequency measurements.  
Duty Cycle and Pulse Width Specifications  
Table 7-11 Duty cycle and pulse width specifications  
Function  
Mode  
Range  
0.01% to 99.99%  
5% to 95%  
Resolution  
Accuracy (at full scale)  
DC Coupling  
AC Coupling  
-
-
0.3% per kHz + 0.3%  
0.3% per kHz + 0.3%  
Duty cycle  
Notes for duty cycle specifications:  
1
2
The accuracy for duty cycle and pulse width is based on a 5 V square wave input into the DC 5 V range.  
For AC coupling, the duty cycle range can be measured for signal frequency > 20 Hz.  
-
-
500 ms  
0.01 ms  
0.1 ms  
0.2% + 3  
0.2% + 3  
Pulse width  
2000 ms  
Notes for pulse width specifications:  
1
2
The accuracy for duty cycle and pulse width is based on a 5 V square wave input into the DC 5 V range.  
Positive or negative pulse width must be greater than 10 µs and the range of duty cycle should be considered. The range  
of pulse width is determined by the frequency of the signal.  
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Frequency Sensitivity Specifications  
For voltage measurements  
Table 7-12 Frequency sensitivity and trigger level specifications for voltage measurements  
Minimum sensitivity (RMS sine wave)  
Trigger level for DC coupling  
Model Number  
Input  
range  
[1]  
U1251A  
U1252A  
U1251A  
U1252A  
20 Hz - 100  
kHz  
>100 kHz - 20 Hz - 200 >200 kHz -  
>100 kHz -  
200 kHz  
> 100 kHz -  
500 kHz  
< 100 kHz  
< 100 kHz  
200 kHz  
15 mV  
35 mV  
50 mV  
kHz  
10 mV  
70 mV  
120 mV  
500 kHz  
25 mV  
50.000 mV  
500.00 mV  
1000.0 mV  
10 mV  
25 mV  
40 mV  
10 mV  
60 mV  
100 mV  
15 mV  
10 mV  
70 mV  
120 mV  
25 mV  
150 mV  
300 mV  
70 mV  
150 mV  
300 mV  
150 mV  
0.5 V/1.25  
V (< 100  
Hz)  
5.0000 V  
0.25 V  
0.5 V  
0.3 V  
1.2 V  
0.6 V  
0.6 V  
1.5 V  
50.000 V  
500.00 V  
2.5 V  
25 V  
5 V  
-
3 V  
5 V  
-
5 V  
6 V  
-
6 V  
15 V  
-
30 V < 100  
kHz  
50 V  
60 V  
50 V < 100  
kHz  
1000.0 V  
50 V  
-
-
300 V  
-
120 V  
-
Notes for frequency sensitivity and trigger level specifications for voltage measurements;  
1
2
Maximum input for specified accuracy = 10 x range or 1000 V.  
The input signal is lower than the product of 20,000,000 V-Hz.  
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For current measurements  
Table 7-13 Frequency sensitivity specifications for current measurements  
Minimum Sensitivity (R.M.S. sine wave)  
Input Range  
20 Hz – 20 kHz  
100 µA  
250 µA  
10 mA  
500.00 µA  
5000.0 µA  
50.000 mA  
440.00 mA  
5.0000 A  
25 mA  
1 A  
Peak Hold Specifications  
Table 7-14 Peak hold specifications for dc voltage and current measurements  
Signal Width  
Accuracy For DC mV/voltage/current  
2% + 400 for all ranges  
Single event > 1 ms  
Repetitive > 250 µs  
2% + 1000 for all ranges  
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Frequency Counter Specifications for U1252A  
Table 7-15 Frequency counter (divide by 1) specifications  
Accuracy  
(% of reading + No.  
Range  
Resolution  
Sensitivity  
Min. Input Frequency  
of Least Significant  
Digit)  
[1]  
99.999 Hz  
999.99 Hz  
9.9999 kHz  
99.999 kHz  
999.99 kHz  
9.9999 MHz  
0.001 Hz  
0.01 Hz  
0.0001 kHz  
0.001 kHz  
0.01 kHz  
0.02% + 3  
100 mV R.M.S.  
200 mV R.M.S.  
0.5 Hz  
0.002% + 5  
< 985 kHz  
0.0001 MHz  
[4]  
Table 7-16 Frequency counter (divide by 100 ) specifications  
Accuracy  
(% of reading + No.  
of Least Significant  
Digit)  
Range  
Resolution  
Sensitivity  
Min. Input Frequency  
9.9999 MHz  
99.99 MHz  
0.0001 MHz  
0.001 MHz  
0.002 % + 5,  
400 mV R.M.S.  
600 mV R.M.S.  
1 MHz  
< 20 MHz  
Notes for frequency counter specifications:  
1
All frequency counters are susceptible to error when measuring low-voltage, low-frequency signals. Shielding inputs from  
picking up external noise is critical for minimizing measurement errors. For non-square wave signals, an additional 5  
counts need to be added.  
2
3
4
The maximum measurement level is < 30 Vpp.  
The minimum measurement frequency of low frequency is set by power-on option to speed up the measurement rate.  
Shown on the secondary display  
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Square Wave Output for U1252A  
Table 7-17 Square wave output specifications  
[1]  
Output  
Range  
Accuracy  
0.5, 1, 2, 5, 10, 15, 20, 25, 30, 40, 50, 60,  
75, 80, 100, 120, 150, 200, 240, 300,  
400, 480, 600, 800, 1200, 1600, 2400,  
4800 Hz  
Frequency  
0.005% x output frequency + 2 counts  
[2][4][5]  
[3]  
Duty Cycle  
0.39% – 99.60%  
1/Frequency  
0.398% of full scale  
[2][4][6]  
Pulse Width  
0.2 ms + (range/256)  
0.2 V  
Amplitude  
Notes for square wave output specifications:  
Fixed 0 to + 2.8 V  
1
2
Output impedance: 3.5 kW maximum.  
The positive or negative pulse width must be greater than 50 µs for adjusting the duty cycle or the pulse width under  
different frequencies. Otherwise the accuracy and the range will be different from the definition.  
For signal frequencies greater than 1 kHz, add 0.1% per kHz to the accuracy.  
The accuracy for duty cycle and pulse width is based on a 5 V square wave input without dividing signal.  
Duty cycle can be set for 256 steps and each step is 0.390625% per kHz.  
3
4
5
6
The pulse width can be set for 256 steps and each step is 1/(256 x Frequency).  
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Specifications  
Operating Specifications  
Display update rate (approximate)  
Table 7-18 Display update rate (approximate)  
Function  
AC V  
Times/second  
7
AC V + dB  
7
DC V (V or mV)  
AC V (V or mV)  
AC+DC V (V or mV)  
Ω / nS  
7
7
2
14  
Diode  
14  
Capacitance  
4 (< 100 µF)  
DC A ( µA, mA, or A)  
AC A ( µA, mA, or A)  
AC+DC A ( µA, mA, or A)  
Temperature  
Frequency  
7
7
2
6
2 (> 10 Hz)  
1 (> 10 Hz)  
1 (> 10 Hz)  
Duty cycle  
Pulse width  
The U1251A and U1252A handheld digital multimeter does not contain a  
realtime clock. Only ONE sample per second can be logged.  
NOTE  
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Specifications  
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Input impedance  
Table 7-19 Input Impedance  
Function  
Range  
Input Impedance  
50.000 mV  
500.00 mV  
1000.0 mV  
5.0000 V  
50.000 V  
500.00 V  
1000.0 V  
50.000 mV  
500.00 mV  
1000.0 mV  
5.0000 V  
50.000 V  
500.00 V  
1000.0 V  
50.000 mV  
500.00 mV  
1000.0 mV  
5.0000 V  
50.000 V  
500.00 V  
1000.0 V  
10.00 MΩ  
10.00 MΩ  
10.00 MΩ  
[1]  
DC Voltage  
11.10 MΩ  
10.10 MΩ  
10.01 MΩ  
10.001 MΩ  
10.00 MΩ  
10.00 MΩ  
10.00 MΩ  
[2]  
AC Voltage  
10.00 MΩ  
10.00 MΩ  
10.00 MΩ  
10.00 MΩ  
10.00 MΩ  
10.00 MΩ  
10.00 MΩ  
[2]  
AC + DC Voltage  
11.10 MΩ // 10 MΩ  
10.10 MΩ // 10 MΩ  
10.01 MΩ // 10 MΩ  
10.001 MΩ // 10 MΩ  
Notes for input impedance:  
1
2
For 5 V to 1000 V range, the specified input impedance in parallel with 10 MΩ at dual display.  
The specified input impedance (nominal) in parallel with <100 pF.  
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Specifications  
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www.agilent.com  
Contact us  
To obtain service, warranty or technical support  
assistance, contact us at the  
following phone numbers:  
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Or visit Agilent worlwide Web at:  
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Product specifications and descriptions in this  
document are subject to change without notice.  
Always refer to the Agilent Web site for the latest  
revision.  
© Agilent Technologies, Inc. 2006 – 2012  
Printed in Malaysia  
Tenth Edition, May 4, 2012  
U1251-90003  
Agilent Technologies  
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