Microchip Technology 5071A User manual

 2022 Microchip Technology Inc. and its subsidiaries DS50003249A
5071A Primary Frequency
Standard User’s Guide

DS50003249A-page 2  2022 Microchip Technology Inc. and its subsidiaries
This publication and the information herein may be used only
with Microchip products, including to design, test, and integrate
Microchip products with your application. Use of this informa-
tion in any other manner violates these terms. Information
regarding device applications is provided only for your conve-
nience and may be superseded by updates. It is your responsi-
bility to ensure that your application meets with your
specifications. Contact your local Microchip sales office for
additional support or, obtain additional support at https://
www.microchip.com/en-us/support/design-help/client-support-
services.
THIS INFORMATION IS PROVIDED BY MICROCHIP "AS IS".
MICROCHIP MAKES NO REPRESENTATIONS OR WAR-
RANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED,
WRITTEN OR ORAL, STATUTORY OR OTHERWISE,
RELATED TO THE INFORMATION INCLUDING BUT NOT
LIMITED TO ANY IMPLIED WARRANTIES OF NON-
INFRINGEMENT, MERCHANTABILITY, AND FITNESS FOR A
PARTICULAR PURPOSE, OR WARRANTIES RELATED TO
ITS CONDITION, QUALITY, OR PERFORMANCE.
IN NO EVENT WILL MICROCHIP BE LIABLE FOR ANY INDI-
RECT, SPECIAL, PUNITIVE, INCIDENTAL, OR CONSE-
QUENTIAL LOSS, DAMAGE, COST, OR EXPENSE OF ANY
KIND WHATSOEVER RELATED TO THE INFORMATION OR
ITS USE, HOWEVER CAUSED, EVEN IF MICROCHIP HAS
BEEN ADVISED OF THE POSSIBILITY OR THE DAMAGES
ARE FORESEEABLE. TO THE FULLEST EXTENT
ALLOWED BY LAW, MICROCHIP'S TOTAL LIABILITY ON
ALL CLAIMS IN ANY WAY RELATED TO THE INFORMATION
OR ITS USE WILL NOT EXCEED THE AMOUNT OF FEES, IF
ANY, THAT YOU HAVE PAID DIRECTLY TO MICROCHIP
FOR THE INFORMATION.
Use of Microchip devices in life support and/or safety applica-
tions is entirely at the buyer's risk, and the buyer agrees to
defend, indemnify and hold harmless Microchip from any and
all damages, claims, suits, or expenses resulting from such
use. No licenses are conveyed, implicitly or otherwise, under
any Microchip intellectual property rights unless otherwise
stated.
Note the following details of the code protection feature on Microchip products:
• Microchip products meet the specifications contained in their particular Microchip Data Sheet.
• Microchip believes that its family of products is secure when used in the intended manner, within operating specifications, and
under normal conditions.
• Microchip values and aggressively protects its intellectual property rights. Attempts to breach the code protection features of
Microchip product is strictly prohibited and may violate the Digital Millennium Copyright Act.
• Neither Microchip nor any other semiconductor manufacturer can guarantee the security of its code. Code protection does not
mean that we are guaranteeing the product is “unbreakable”. Code protection is constantly evolving. Microchip is committed to
continuously improving the code protection features of our products.
Trademarks
The Microchip name and logo, the Microchip logo, Adaptec,
AnyRate, AVR, AVR logo, AVR Freaks, BesTime, BitCloud,
CryptoMemory, CryptoRF, dsPIC, flexPWR, HELDO, IGLOO,
JukeBlox, KeeLoq, Kleer, LANCheck, LinkMD, maXStylus,
maXTouch, MediaLB, megaAVR, Microsemi, Microsemi logo,
MOST, MOST logo, MPLAB, OptoLyzer, PIC, picoPower,
PICSTART, PIC32 logo, PolarFire, Prochip Designer, QTouch,
SAM-BA, SenGenuity, SpyNIC, SST, SST Logo, SuperFlash,
Symmetricom, SyncServer, Tachyon, TimeSource, tinyAVR, UNI/O,
Vectron, and XMEGA are registered trademarks of Microchip
Technology Incorporated in the U.S.A. and other countries.
AgileSwitch, APT, ClockWorks, The Embedded Control Solutions
Company, EtherSynch, Flashtec, Hyper Speed Control, HyperLight
Load, IntelliMOS, Libero, motorBench, mTouch, Powermite 3,
Precision Edge, ProASIC, ProASIC Plus, ProASIC Plus logo, Quiet-
Wire, SmartFusion, SyncWorld, Temux, TimeCesium, TimeHub,
TimePictra, TimeProvider, TrueTime, WinPath, and ZL are
registered trademarks of Microchip Technology Incorporated in the
U.S.A.
Adjacent Key Suppression, AKS, Analog-for-the-Digital Age, Any
Capacitor, AnyIn, AnyOut, Augmented Switching, BlueSky,
BodyCom, CodeGuard, CryptoAuthentication, CryptoAutomotive,
CryptoCompanion, CryptoController, dsPICDEM, dsPICDEM.net,
Dynamic Average Matching, DAM, ECAN, Espresso T1S,
EtherGREEN, GridTime, IdealBridge, In-Circuit Serial
Programming, ICSP, INICnet, Intelligent Paralleling, Inter-Chip
Connectivity, JitterBlocker, Knob-on-Display, maxCrypto, maxView,
memBrain, Mindi, MiWi, MPASM, MPF, MPLAB Certified logo,
MPLIB, MPLINK, MultiTRAK, NetDetach, NVM Express, NVMe,
Omniscient Code Generation, PICDEM, PICDEM.net, PICkit,
PICtail, PowerSmart, PureSilicon, QMatrix, REAL ICE, Ripple
Blocker, RTAX, RTG4, SAM-ICE, Serial Quad I/O, simpleMAP,
SimpliPHY, SmartBuffer, SmartHLS, SMART-I.S., storClad, SQI,
SuperSwitcher, SuperSwitcher II, Switchtec, SynchroPHY, Total
Endurance, TSHARC, USBCheck, VariSense, VectorBlox, VeriPHY,
ViewSpan, WiperLock, XpressConnect, and ZENA are trademarks
of Microchip Technology Incorporated in the U.S.A. and other
countries.
SQTP is a service mark of Microchip Technology Incorporated in
the U.S.A.
The Adaptec logo, Frequency on Demand, Silicon Storage
Technology, Symmcom, and Trusted Time are registered
trademarks of Microchip Technology Inc. in other countries.
GestIC is a registered trademark of Microchip Technology Germany
II GmbH & Co. KG, a subsidiary of Microchip Technology Inc., in
other countries.
All other trademarks mentioned herein are property of their
respective companies.
© 2022, Microchip Technology Incorporated and its subsidiaries.
All Rights Reserved.
ISBN: 978-1-6683-0138-8
For information regarding Microchip’s Quality Management Systems,
please visit www.microchip.com/quality.

5071A PRIMARY FREQUENCY
STANDARD USER’S GUIDE
 2022 Microchip Technology Inc. DS50003249A-page 3
Preface
PURPOSE OF THIS GUIDE
The 5071A user’s guide provides basic recommendations for use of Microchip's 5071A
primary frequency standard. The guidelines in the document are generic because spe-
cific product requirements vary from one application to the other.
This material consists of a brief description of 5071A features, programming, and oper-
ating instructions.
WHO SHOULD READ THIS GUIDE
This document is intended for engineers and telecommunications professionals who
are designing, installing, operating, or maintaining time, frequency, and synchroniza-
tion systems having a requirement for a primary frequency reference.
To use this document effectively, you should have a good understanding of digital tele-
communications technologies and analog frequency generation and synthesis tech-
niques.
DOCUMENT LAYOUT
This guide contains the following sections:
•Chapter 1. “Introduction”: Provides an overview of the product features, princi-
ple of operations, and safety considerations.
•Chapter 2. “Getting Started”: Provides basic information on the indicators, con-
trols, connectors and powering sequences.
•Chapter 3. “Using the 5071A”: Provides detailed operating instructions for the
instrument including configuration and disciplining to external sources.
•Chapter 4. “Troubleshooting Tips”: Provides information on error messages,
warning indicators, and interpreting log informations.
•Chapter 5. “Remote Operating and Programming”: Contains information for
remote control of the instrument and programming examples.
•Chapter 6. “Command Reference”: Contains the detailed command list for pro-
gramming and remote operation.
NOTICE TO CUSTOMERS
All documentation becomes dated, and this manual is no exception. Microchip tools and
documentation are constantly evolving to meet customer needs, so some actual dialogs
and/or tool descriptions may differ from those in this document. Please refer to our website
(www.microchip.com) to obtain the latest documentation available.
Documents are identified with a “DS” number. This number is located on the bottom of each
page, in front of the page number. The numbering convention for the DS number is
“DSXXXXXXXXA”, where “XXXXXXXX” is the document number and “A” is the revision level
of the document.
For the most up-to-date information on development tools, see the MPLAB® IDE online help.
Select the Help menu, and then Topics, to open a list of available online help files.

Preface
 2022 Microchip Technology Inc. DS50003249A-page 4
•Chapter 7. “Specifications”: Contains equipment specifications not included on
the data sheet, and definitions of specifications on the data sheets.
•Chapter 8. “Installation”: Provides information on external requirements and
maintenance procedures.
•Appendix A. “Performance Tests”: Provides information on the power up start
test and serial port verifications.
•Appendix B. “Product Variations”: Details all model numbers and product con-
figurations.
•Appendix C. “Glossary”
CONVENTIONS USED IN THIS GUIDE
This manual uses the following documentation conventions:
DOCUMENTATION CONVENTIONS
Description Represents Examples
Arial font:
Italic characters Referenced books MPLAB® IDE User’s Guide
Emphasized text ...is the only compiler...
Initial caps A window the Output window
A dialog the Settings dialog
A menu selection select Enable Programmer
Quotes A field name in a window or
dialog
“Save project before build”
Underlined, italic text with
right angle bracket
A menu path File>Save
Bold characters A dialog button Click OK
A tab Click the Power tab
N‘Rnnnn A number in verilog format,
where N is the total number of
digits, R is the radix and n is a
digit.
4‘b0010, 2‘hF1
Text in angle brackets < > A key on the keyboard Press <Enter>, <F1>
Courier New font:
Plain Courier New Sample source code #define START
Filenames autoexec.bat
File paths c:\mcc18\h
Keywords _asm, _endasm, static
Command-line options -Opa+, -Opa-
Bit values 0, 1
Constants 0xFF, ‘A’
Italic Courier New A variable argument file.o, where file can be
any valid filename
Square brackets [ ] Optional arguments mcc18 [options] file
[options]
Curly brackets and pipe
character: { | }
Choice of mutually exclusive
arguments; an OR selection
errorlevel {0|1}
Ellipses... Replaces repeated text var_name [,
var_name...]
Represents code supplied by
user
void main (void)
{ ...
}

Preface
 2022 Microchip Technology Inc. DS50003249A-page 5
WARNINGS, CAUTIONS, RECOMMENDATIONS, AND NOTES
Warnings, Cautions, Recommendations, and Notes attract attention to essential or crit-
ical information in this guide. The types of information included in each are displayed
in a style consistent with the examples below.
WHERE TO FIND ANSWERS TO PRODUCT AND DOCUMENT QUESTIONS
For additional information about the products described in this guide, please contact
your Microchip representative or your local sales office. You can also contact us on the
web at http://www.microsemi.com/ftdsupport.
When this manual is updated the latest version will be available for downloading from
Microchip’s web site. Manuals are provided in PDF format for ease of use. After down-
loading, you can view the manual on a computer or print it using Adobe Acrobat
Reader.
Manual updates are available at: http://www.microsemi.com/ftdsupport.
RELATED DOCUMENTS AND INFORMATION
See your Microchip representative or sales office for a complete list of available docu-
mentation. To order any accessory, contact the Microchip Sales Department. See
www.microsemi.com/sales-contacts/0 for sales support contact information. If you
encounter any difficulties installing or using the product, contact Microchip Frequency
and Time Systems (FTS) Services and Support:
U.S.A. Call Center: including Americas, Asia and Pacific Rim
Microchip Frequency and Time Systems
3870 N 1st St.
San Jose, CA 95134
Toll-free in North America: 1-888-367-7966
Telephone: [phone]
WARNING
To avoid serious personal injury or death, do not disregard warnings. All warnings use
this style. Warnings are installation, operation, or maintenance procedures, practices,
or statements, that if not strictly observed, may result in serious personal injury or even
death.
CAUTION
To avoid personal injury, do not disregard cautions. All cautions use this style. Cau-
tions are installation, operation, or maintenance procedures, practices, conditions, or
statements, that if not strictly observed, may result in damage to, or destruction of, the
equipment. Cautions are also used to indicate a long-term health hazard.
Note: All notes use this style. Notes contain installation, operation, or mainte-
nance procedures, practices, conditions, or statements that alert you to
important information, which may make your task easier or increase your
understanding.

Preface
 2022 Microchip Technology Inc. DS50003249A-page 6
Fax: [phone]
email: [email protected]
Internet: http://www.microsemi.com/ftdsupport
Europe, Middle East, and Africa (EMEA)
Microchip FTS Services and Support EMEA
Altlaufstrasse 42
85635 Hoehenkirchen-Siegertsbrunn
Germany
Telephone: [phone]
Fax: [phone]
email: [email protected]
email: [email protected]
South Asia
Suite A201, 2nd Floor,West Wing, Wisma Consplant 2, No. 7, Jalan SS16/1, 47500
Subang Jaya Selangor, Malaysia
Toll-free in North America: 1-888-367-7966, Option 1
Telephone: [phone]
email: [email protected]
THE MICROCHIP WEBSITE
Microchip provides online support via our website at www.microchip.com. This website
is used as a means to make files and information easily available to customers.
Accessible by using your favorite Internet browser, the website contains the following
information:
•Product Support – Data sheets and errata, application notes and sample
programs, design resources, user’s guides and hardware support documents,
latest software releases and archived software
•General Technical Support – Frequently Asked Questions (FAQs), technical
support requests, online discussion groups, Microchip consultant program
member listing
•Business of Microchip – Product selector and ordering guides, latest Microchip
press releases, listing of seminars and events, listings of Microchip sales offices,
distributors and factory representatives
CUSTOMER SUPPORT
Users of Microchip products can receive assistance through several channels:
• Distributor or Representative
• Local Sales Office
• Field Application Engineer (FAE)
• Technical Support
Customers should contact their distributor, representative or field application engineer
(FAE) for support. Local sales offices are also available to help customers. A listing of
sales offices and locations is included in the back of this document.
Technical support is available through the website at:
http://www.microchip.com/support.

Preface
 2022 Microchip Technology Inc. DS50003249A-page 7
DOCUMENT REVISION HISTORY
Revision A (March 2022)
• Initial release of this document as Microchip DS50003249A.
- Under Microsemi’s literature system, this document was 05071-90041, Rev. J

5071A PRIMARY FREQUENCY
STANDARD USER’S GUIDE
 2022 Microchip Technology Inc. DS50003249A-page 8
Table of Contents
Preface ........................................................................................................................... 3
Purpose of This Guide.......................................................................................... 3
Who Should Read This Guide.............................................................................. 3
Document Layout ................................................................................................. 3
Conventions Used in this Guide ........................................................................... 4
Warnings, Cautions, Recommendations, and Notes............................................ 5
Where to Find Answers to Product and Document Questions ............................. 5
Related Documents and Information.................................................................... 5
The Microchip Website......................................................................................... 6
Customer Support ................................................................................................ 6
Document Revision History .................................................................................. 7
Chapter 1. Introduction................................................................................................ 12
1.1 What is the 5071A Primary Frequency Standard? ........................................ 12
1.2 How Does the 5071A Work? ......................................................................... 12
1.3 5071A Major Features................................................................................... 12
1.4 System Applications ...................................................................................... 13
1.5 Instruments Covered by this User’s Guide.................................................... 13
1.6 Operating the 5071A ..................................................................................... 13
1.6.1 Signal Outputs............................................................................................ 13
1.6.2 Clock Functions.......................................................................................... 13
1.7 Safety Considerations ................................................................................... 15
1.7.1 General....................................................................................................... 15
1.7.2 Before Applying Power............................................................................... 15
1.7.3 Before Cleaning.......................................................................................... 16
1.7.4 Safety Earth Ground................................................................................... 16
1.7.5 Heeding Cautions....................................................................................... 16
1.7.6 Rack Mounting ........................................................................................... 16
1.7.7 AC Power Supply ....................................................................................... 17
1.7.8 DC Power Supply (VDC Operation Model) Installation .............................. 17
1.7.9 Acoustic Noise Emissions .......................................................................... 17
1.7.10 Electrostatic Discharge Immunity Testing ................................................ 17
1.7.11 DC Power Supply (48 VDC Operation Model) Installation ....................... 17
1.7.12 Certification .............................................................................................. 18
1.7.13 Assistance ................................................................................................ 18
Chapter 2. Getting Started........................................................................................... 20
2.1 The 5071A at a Glance ................................................................................. 20
2.1.1 Indicators.................................................................................................... 20
2.1.2 Controls ...................................................................................................... 20
2.1.3 Connectors ................................................................................................. 20

5071A Primary Frequency Standard User’s Guide
DS50003249A-page 9  2022 Microchip Technology Inc.
2.2 Rear Panel Connections ............................................................................... 22
2.3 Starting the 5071A......................................................................................... 24
2.4 Performing Basic Tasks ................................................................................ 25
2.4.1 Synchronizing to an External 1PPS Reference ..........................................25
2.4.2 Setting Time and Date ................................................................................26
2.4.3 Powering Down the 5071A .........................................................................26
Chapter 3. Using the 5071A .........................................................................................28
3.1 Using the Front-Panel Menus........................................................................ 28
3.1.1 Keypad Descriptions...................................................................................28
3.1.2 Controlling the 5071A From the Front Panel ..............................................28
3.2 Setting the Output Port Frequency................................................................ 29
3.3 Setting the 1PPS and Clock Outputs ............................................................ 29
3.3.1 To Set the 1PPS Outputs............................................................................29
3.3.2 To Synchronize the 1PPS Outputs Using a Time-Interval Counter ............29
3.3.3 To Set the Clock .........................................................................................30
3.3.4 To Turn the Clock Display On or Off...........................................................31
3.3.5 To Schedule a Leap Second.......................................................................31
3.4 Monitoring Status .......................................................................................... 31
3.4.1 To Select Parameters .................................................................................31
3.4.2 To Interpret Displayed Results....................................................................31
3.4.3 To Print a Status Report .............................................................................32
3.5 Reading and Managing the Event Log.......................................................... 32
3.5.1 To Check Log Status ..................................................................................32
3.5.2 To View Log Entries....................................................................................32
3.5.3 To Clear the Log .........................................................................................32
3.5.4 To Print the Log ..........................................................................................32
3.6 Steering the Output Frequency ..................................................................... 32
3.6.1 Steering Explained......................................................................................32
3.6.2 To Add an Offset.........................................................................................33
3.6.3 To Check an Offset.....................................................................................33
3.6.4 To Remove an Offset..................................................................................33
3.7 Using Utility Features .................................................................................... 34
3.7.1 To Reset the Continuous Operation Light...................................................34
3.7.2 To Reset the Rear-Panel Status Output .....................................................34
3.7.3 To Display the Firmware Revision or CBT Identification String ..................34
3.7.4 Diagnostic Self-Tests ..................................................................................34
3.8 Configuring the 5071A................................................................................... 35
3.8.1 To Set the Operating Mode.........................................................................35
3.8.2 To Set the Printer Log Mode.......................................................................35
3.8.3 To Set Up the Serial Port............................................................................35
3.8.4 To Save a Configuration .............................................................................36
3.9 Connecting a Printer...................................................................................... 36
3.10 Disabling the Internal-Standby Battery........................................................ 36
Chapter 4. Troubleshooting Tips ................................................................................38
4.1 Front-Panel Indicators and Messages........................................................... 38
4.1.1 Clock Display ..............................................................................................38
4.1.2 Attention Light.............................................................................................38
4.1.3 Continuous Operation Light ........................................................................38

 2022 Microchip Technology Inc. DS50003249A-page 10
4.1.4 LCD Display ............................................................................................... 39
4.1.5 Instrument States ....................................................................................... 40
4.1.6 Front-Panel Warning Messages................................................................. 40
4.2 Power-up Problems....................................................................................... 41
4.3 Using Menus to Check Operational Status ................................................... 41
4.3.1 INFOrmation Menu..................................................................................... 41
4.3.2 LOG Menu.................................................................................................. 41
4.3.3 UTILities Menu ........................................................................................... 42
4.3.4 CLOCK Menu ............................................................................................. 42
4.3.5 CONFIGuration Menu ................................................................................ 42
4.4 Operating System Failure.............................................................................. 42
4.4.1 Operating System Failure Symptoms......................................................... 42
4.4.2 Restarting the 5071A.................................................................................. 42
4.5 Cesium Beam Tube Life................................................................................ 43
Chapter 5. Remote Operating and Programming...................................................... 44
5.1 Remote-Operation Setup .............................................................................. 44
5.1.1 Remote Interface Features......................................................................... 44
5.1.2 Serial-Port Description ............................................................................... 44
5.1.3 Hardware Connection................................................................................. 44
5.1.4 Serial-Port Configuration ............................................................................ 45
5.2 Programming Overview................................................................................. 46
5.3 SCPI Command Conformance...................................................................... 46
5.4 Command Types ........................................................................................... 46
5.4.1 Common Command Format....................................................................... 46
5.4.2 SCPI Command and Query Format ........................................................... 47
5.4.3 *RST Reset Response ............................................................................... 49
5.5 Sample Program Commands ........................................................................ 49
5.5.1 Status Monitoring Tasks............................................................................. 50
5.5.2 Instrument Control Tasks ........................................................................... 50
5.6 Batch Processing for the Program Commands ............................................. 52
5.6.1 Command Scripts On a Personal Computer .............................................. 52
5.6.2 SCPI Considerations For HP BASIC.......................................................... 52
5.6.3 Example Program....................................................................................... 53
5.7 Tips on Using the RS-232C Port on the 5071A............................................. 57
5.7.1 Keypad Lock-Ups: Why Do They Occur and How Are They Cleared? ...... 57
5.7.2 Using Ctrl-Q in Programs ........................................................................... 58
5.8 Setting the Serial Port Parameters with the Option 300 Front Panel ............ 58
Chapter 6. Command Reference................................................................................. 60
6.1 5071A Command Summary .......................................................................... 60
6.1.1 IEEE 488.2 Common Commands .............................................................. 60
6.1.2 SCPI Commands........................................................................................ 61
6.2 Description of SCPI Commands.................................................................... 65
6.2.1 Diagnostic Commands ............................................................................... 65
6.2.2 Display Commands .................................................................................... 68
6.2.3 Precision Time (Date and Time) Commands ............................................. 69
6.2.4 Reference Oscillator Commands................................................................ 71
6.2.5 STATus Monitoring Commands ................................................................. 72
6.2.6 System Commands .................................................................................... 75

5071A Primary Frequency Standard User’s Guide
DS50003249A-page 11  2022 Microchip Technology Inc.
6.3 Status Reporting............................................................................................ 78
6.4 Rear Panel Status Output Operation............................................................. 80
6.4.1 Status Output Programming .......................................................................80
6.5 Serial-Port Command/Printer Interface ......................................................... 82
6.5.1 Mode Selection ...........................................................................................82
6.5.2 Pacing .........................................................................................................82
6.5.3 The Prompt .................................................................................................82
6.5.4 End-Of-Line Characters ..............................................................................82
6.6 Error Messages/Codes.................................................................................. 83
Chapter 7. Specifications.............................................................................................86
7.1 Supplemental Characteristics........................................................................ 86
7.1.1 Time Standard ............................................................................................86
7.1.2 Internal Standby Battery (Nominal Values).................................................86
7.1.3 Accessories and Options ............................................................................87
7.2 Specification Definitions ................................................................................ 88
Chapter 8. Installation ..................................................................................................90
8.1 Initial Inspection............................................................................................. 90
8.2 Preparation for Use ....................................................................................... 90
8.2.1 Power Requirements ..................................................................................90
8.2.2 Selecting Line Voltage and Fuse (For Units Delivered Prior to 23 August
2016).......................................................................................................91
8.2.3 AC Power Cabling.......................................................................................92
8.2.4 Operating Environment...............................................................................93
8.3 Returning the 5071A to Microchip................................................................. 93
8.4 Operator’s Maintenance................................................................................ 95
8.5 Operating the 5071A From External DC Power ............................................ 95
8.5.1 Preparing the 5071A For External DC Operation .......................................95
8.5.2 Replacing the External DC Input Power Fuse ............................................96
8.6 Internal Standby Battery Maintenance .......................................................... 96
8.6.1 Battery Shelf Life and Storage....................................................................96
8.6.2 Battery Operating Temperatures ................................................................97
8.6.3 Battery Charging.........................................................................................97
8.6.4 Battery Disposal..........................................................................................98
8.6.5 Using the Battery Disconnect Switch..........................................................98
8.6.6 Removing and Replacing the Internal Battery ............................................98
8.7 Cesium Beam Tube Replacement ................................................................ 99
8.8 Long-Term Storage ....................................................................................... 99
Appendix A. Performance Tests ...............................................................................100
A.1 Power-On Self-Tests and Servo Lock......................................................... 100
A.2 RS-232 Serial Port Verification ................................................................... 101
Appendix B. Product Variations................................................................................102
Appendix C. Glossary ................................................................................................104
Worldwide Sales and Service...................................................................................106

5071A PRIMARY FREQUENCY
STANDARD USER’S GUIDE
 2022 Microchip Technology Inc. DS50003249A-page 12
Chapter 1. Introduction
This section describes the 5071A's features and provides information to better under-
stand them so you can operate the instrument effectively. The following is a functional
narrative description. For specific details such as signal levels, accuracy, stability, and
more, see the most recent data sheet:
https://www.microsemi.com/document-portal/doc_download/133269-5071a-datasheet
1.1 WHAT IS THE 5071A PRIMARY FREQUENCY STANDARD?
The 5071A is a source of extremely accurate and stable output frequencies. The accu-
racy of the 5071A is within a few parts in 1013 of the internationally accepted definition
of frequency. This accuracy is made more usable and practical by the 5071A's excel-
lent environmental stability.
1.2 HOW DOES THE 5071A WORK?
The 5071A uses a fundamental property of the element cesium to define frequency.
Inside the cesium beam tube assembly, an applied microwave signal causes
energy-level transitions to occur in the cesium atoms. The microwave signal is synthe-
sized from a 10 MHz voltage-controlled crystal oscillator (VCXO). Patented Cesium II
circuit and software technology detects departures of the microwave frequency from
the cesium energy-level transition frequency and corrects them by tuning the VCXO to
run precisely at the proper rational-fraction of the cesium frequency. The microproces-
sor (an integral part of this servo loop) performs the error determination and correction
several times a second to ensure that the VCXO is always closely locked to the
cesium-transition frequency.
Many functions within the 5071A are under Cesium II software control. The software
manages the initial warm-up and alignment, then continuously monitors the appropri-
ate signals using this information to control all key operating parameters for optimum
performance. Starting the 5071A merely requires connecting AC or DC power.
After a typical warm-up time of 15 minutes, the standard is fully operational and the
operator may optionally press three keys to display a continuous operation signal.
There are no maintenance procedures or adjustments needed even when necessary
to replace the cesium beam tube. The 5071A meets all specifications within 30 minutes
of power connection at room temperature.
1.3 5071A MAJOR FEATURES
• 5 MHz or 10 MHz programmable outputs
• Dedicated 1 MHz and 100 kHz outputs
• Time and date clocks
• Easily synchronized 1 pulse per second (1PPS) outputs
• 45-minute standby battery (some models do not have batteries. Refer to Appendix
B. for more information.)
• Accurate and precise output frequency steering
• Event log

5071A Primary Frequency Standard User’s Guide
DS50003249A-page 13  2022 Microchip Technology Inc.
1.4 SYSTEM APPLICATIONS
As a system component, the 5071A's function is significantly enhanced by its capacity
for complete remote control through an RS-232C port on the rear panel. All front-panel
functions can be programmed through the port as well as many functions not available
through the front panel controls. The RS-232C port allows the instrument to:
• Print status reports and internal parameters to an external printer
• Communicate with and be controlled by a data terminal or computer
1.5 INSTRUMENTS COVERED BY THIS USER’S GUIDE
The 5071A has a two-part serial number in the form US00000000 that appears on the
serial number plate attached to the rear of the instrument. The first four numerical digits
constitute the serial number prefix and the last 4 significant digits form the suffix. The
prefix is the same for all identical instruments. It changes only when a change is made
to the instrument. The suffix, however, is assigned sequentially and is different for each
instrument. This manual applies directly to instruments having the serial prefix as
US4935.
For information concerning a serial number prefix that is not listed, contact the nearest
Microchip Customer Service Center.
1.6 OPERATING THE 5071A
Local operation of the 5071A is performed on the control panel located behind the front
panel door. Here you will find the 5071A's controls and Liquid Crystal Display (LCD).
The LCD is backlit for better visibility whenever any key is pressed.
1.6.1 Signal Outputs
There are four sinusoidal outputs available on the 5071A: two fixed frequency outputs
of 1 MHz and 100 kHz, and two programmable output ports. Each programmable out-
put port can be set to emit a 5 MHz or 10 MHz signal. These ports are isolated from
each other so that noise or impedance changes on one port cannot significantly affect
the amplitude or phase of the signal on any other port. An additional property of these
outputs is that they are phase consistent. That is, when the frequency on a port is
changed then returned to the original frequency, the original phase is restored.
1.6.2 Clock Functions
The clock functions use the large six-digit LED display, the 1PPS outputs, and their
control circuits. The 1PPS outputs are movable in time and can be automatically syn-
chronized with other 1PPS sources. Clock adjustment procedures can be found in
Using the 5071A.
Clock display: On power-up, the clock display is OFF so the clock will not display an
incorrect time. The display may be set and turned on using the front-panel controls or
the RS-232C interface. If you plan to use the Modified Julian Day (MJD) date system,
the time should be set to Coordinated Universal Time (UTC). See more information
about the MJD later in this section.
1PPS outputs: There are three 1PPS outputs on the 5071A, one on the front panel and
two on the rear panel. All are synchronous (pulses occur at the same time) and isolated
from each other so that a short circuit or other disturbance on one cannot affect the
amplitude or timing on the others.
Note: Not all models contain a display, door, or keypad. Please refer to Appendix
B. for product configurations.

Introduction
 2022 Microchip Technology Inc. DS50003249A-page 14
All 1PPS outputs are TTL-compatible and are designed for 50Ω termination. You can
automatically synchronize the 1PPS signals to an external 1PPS, or manually change
their timing by up to ±500 ms in 50 ns steps. For automatic sync, there are two refer-
ence inputs: one on the front panel and one on the rear panel. You select either input
using the front-panel controls or via RS-232.
Leap second: The 5071A can be easily set to add or delete a leap second on a desig-
nated day. The leap second is automatically added-to or subtracted-from the last min-
ute of the day. There is no need for operator intervention when the actual leap-second
alteration occurs.
Modified Julian Day (MJD): The Modified Julian Day is a number that is unique for each
day. This numbering system is widely used by astronomers and scientists to tag data
and events. Within the 5071A, the MJD is used for two purposes:
• To tag events kept in the instrument's event log
• To program the insertion or deletion of a leap second at a future date
The MJD increments at 00:00:00 hours Coordinated Universal time (UTC). To ensure
proper synchronization of the MJD setting, the clock display must be set to UTC. If the
MJD is not set, the 5071A will start with 00000 in its MJD counter and increment from
there each time the clock display passes 00:00:00 hours. See Using the 5071A for
information on how to determine and set the current MJD.
Steering (or offsetting) the 5071A output frequency: The 5071A output frequency can
be steered in a very precise and calibrated manner. When steered, the stability of the
output signals is identical to the un-steered signal.
You can steer the 5071A over a range of ±1 part in 109 with a resolution of 6.331991
parts in 1015. These specifications are called the settability of the 5071A.
Steering is accomplished by changing the ratio between the VCXO output frequency
and the cesium transition frequency through a digital synthesizer. The reference fre-
quency of the cesium beam tube is not disturbed. This system has the following advan-
tages over previous cesium beam frequency standards:
• No change in stability of steered output over un-steered output
• Offset from un-steered frequency is precisely known
• Fast change to the precise steered frequency
• Fast and precise return to the original frequency
As a result of knowing the exact amount that the 5071A has been steered, its value as
an independent frequency source in an ensemble is maintained.
Event Log: The event log automatically stores significant events such as power supply
changes, system warnings, and error messages. The event log has the following fea-
tures:
• Non-volatile memory: all data remains if power is lost
• Stores 190 events
• Each logged event is time-and-date tagged
• Log may be read locally or through the RS-232C port
Power input and management: The 5071A operates from either AC or DC power. An
internal-standby battery provides at least 45 minutes of operating power (see Appendix
B. for model numbers with batteries). Power-source priority is controlled by the 5071A.
The priority order is:
1. AC-line power: when below the specified minimum voltage or if absent, the
5071A switches to,
2. External-DC power: if this fails or goes below 22VDC, the 5071A switches to,
3. Internal-standby battery power (if model is configured with battery).

5071A Primary Frequency Standard User’s Guide
DS50003249A-page 15  2022 Microchip Technology Inc.
For 48V option the priority order is:
1. External-DC power: when below the specified minimum voltage (40VDC on both
DC inputs), or when absent, the 5071A switches to,
2. AC-line power
Remote operation: The 5071A may be operated completely through remote control.
The RS-232C port on the rear panel allows the 5071A to be connected to a computer.
The 5071A is programmed in a standard language called standard commands for pro-
grammable instruments (SCPI) based on IEEE 488.2.
Status output: The rear-panel status port gives you an additional option for remote mon-
itoring of the 5071A's operating status. In its default mode, the rear-panel status output
indicates when the continuous operation light goes out. You can re-program this output
to activate on other combinations of internal events.
The status output is TTL with the active state asserted LOW. The status outputs of sev-
eral 5071As can be connected in parallel (in a wired-OR configuration) to operate a
system monitor or act as a service request signal for a computer. See Rear Panel Sta-
tus Output Operation for details.
Operating modes: There are two operating modes: Normal and Standby. The default
mode is Normal. The operating mode should never be changed from Normal to
Standby except under special circumstances. These are described as follows. Placing
the 5071A in standby mode will cause a loss of time and frequency accuracy.
• Normal mode: The 5071A always powers up in this mode. Use this mode for all
normal operation and timekeeping.
• Standby mode: The Standby mode is enabled through the Utility menu and is
used for two special purposes:
- Long term storage: Use Standby when the 5071A is stored more than 3
months. For more information, see Long-Term Storage.
- Service: If a failure occurs, diagnostics operate in Standby mode.
Remote operation: The remote state can only be entered through remote command
through the RS-232C port. In this state, the 5071A operates normally with the
front-panel controls locked out: no changes can be made to parameters (like 1PPS
delay), and no actions can be taken through the front panel. Status information how-
ever, can be read when the front panel is locked. If any disallowed operations are
attempted the 5071A beeps and displays a message. Remote operation is indicated on
the front-panel display with a small lock symbol on the right-hand side.
1.7 SAFETY CONSIDERATIONS
1.7.1 General
This product and related documentation must be reviewed for familiarization with this
safety markings and instructions before operation.
This product is a safety Class I instrument (provided with a protective earth terminal).
If this instrument is used in a manner not specified by Microchip, the protection pro-
vided by the equipment may be impaired.
1.7.2 Before Applying Power
Verify that the product is set to match the available line voltage and the correct fuse is
installed. Refer to instructions in the Getting Started section.

Introduction
 2022 Microchip Technology Inc. DS50003249A-page 16
1.7.3 Before Cleaning
Disconnect the product from operating power before cleaning. Clean only with lightly
damp cloth and mild detergents. Do not get unit wet.
1.7.4 Safety Earth Ground
An uninterruptible safety earth ground is recommended from the main power source to
the product’s input wiring terminals or supplied power cable. The terminal is located on
the rear of the unit near the AC input receptacle.
1.7.5 Heeding Cautions
1.7.6 Rack Mounting
The Model 5071A unit is designed for mounting in a standard 19-inch (48.26 cm) rack.
Follow the rack manufacturer's instructions for mounting the Model 5071A unit while
observing the following guidelines:
• Elevated operating temperature: If the Model 5071A unit is installed in a closed or
multi-unit rack assembly, the ambient temperature of the rack environment may
be greater than the Model 5071A unit's Maximum Operating Temperature of
50°C/122°F. Install the Model 5071A unit in an environment that is compatible with
the Model 5071A unit's operating temperature range, which is 0°C to 50°C, or
32°F to 122°F.
• Mechanical loading: Mount the Model 5071A unit so as to avoid uneven mechani-
cal loading that could cause hazardous conditions.
• Circuit overloading: Observe the power ratings on the Model 5071A unit's name-
plate and the additional load the Model 5071A unit may place on the supply cir-
cuit. Overloading the supply circuit may adversely affect the supply wiring and
overcurrent protection.
• Reliable earthing: Maintain reliable earthing (grounding) of rack mounted equip-
ment. Pay particular attention to supply connections other than direct connections
to the branch circuit (for example, use of power strips).
CAUTION
Damage to equipment or incorrect measurement data may result from failure to heed a
caution. Do not proceed beyond a CAUTION sign until the indicated conditions are fully
understood and met. Whenever it is likely that the protection has been impaired, the
instrument must be made inoperative and be secured against any unintended opera-
tion. If this instrument is to be energized through an autotransformer (for voltage
reduction) make sure the common terminal is connected to the earthed pole terminal
(neutral) of the power source. Instructions for adjustments while covers are removed
and for servicing are for use by service-trained personnel only. To avoid dangerous
electric shock, do not perform such adjustments or servicing unless qualified to do so.
WARNING
Bodily injury or death may result from failure to heed a warning. Do not proceed
beyond a warning sign until the indicated conditions are fully understood and met.

5071A Primary Frequency Standard User’s Guide
DS50003249A-page 17  2022 Microchip Technology Inc.
1.7.7 AC Power Supply
1.7.8 DC Power Supply (VDC Operation Model) Installation
• Use a 15 Amp DC circuit breaker in series with the DC power source.
• Do not connect the unit directly to a DC power source without the breaker.
• 14 AWG (1.5 mm2) gauge wire is the minimum gage permitted by the NEC for DC
power source hookup.
• The Unit Chassis must be grounded for proper safety.
1.7.9 Acoustic Noise Emissions
LpA < 47 dB at operator position, at normal operation, tested per EN 27779. All data
are the results from type test.
1.7.10 Electrostatic Discharge Immunity Testing
When the product is tested with 8 kV AD, 4 kV CD, and 4 kV ID according to IEC801-2,
a system error may occur that may affect measurement data made during these distur-
bances. After these occurrences, the system self-recovers without user intervention.
1.7.11 DC Power Supply (48 VDC Operation Model) Installation
Connecting the 48VDC Operation Unit to DC power:
• Use a 15 Amp DC circuit breaker in series with the DC power source.
WARNING
The Model 5071A unit should only be plugged into a grounded receptacle. Microchip
recommends that the chassis external ground be connected to a reliable earth ground.
Any interruption of the protective grounding conductor (inside or outside the instru-
ment) or disconnecting the protective earth terminal will cause a potential shock haz-
ard that could result in personal injury. Grounding one conductor of a two-conductor
outlet is not sufficient protection.
WARNING
For continued protection against fire, replace the line fuse(s) only with 250V fuse(s) of
the same current rating and type (for example, normal blow, time delay). Do not use
repaired fuses or short-circuited fuse holders.
WARNING
Ensure that a disconnect device, such as a switch, with the appropriate voltage/current
rating is provided when connecting a DC power source to the 48VDC Operation Model.
WARNING
Remove any power connections prior to servicing the interior of a unit.
Note: The 48VDC Operation Model is supplied with two 48VDC inputs to accom-
modate input from an alternate DC Power Source.

Introduction
 2022 Microchip Technology Inc. DS50003249A-page 18
• Do not connect the unit directly to a DC power source without the breaker.
• 14 AWG (1.5 mm2) gauge wire is the minimum gage recommended for DC power
source hookup.
• The 48VDC configuration unit is only to be used in a restricted access area.
• The screw torque on the power terminal block is 4.5- to 5.3-inch pounds.
• When connecting to a DC power source, first connect the positive power cable to
"+" on the power supply, then connect the negative power supply cable to "–". The
unit chassis must be grounded for proper safety.
• The 48VDC unit is supplied with a cover 05071-00053. This cover should be
attached when operating with 48VDC supplies.
1.7.12 Certification
Microchip certifies that this product met its published specification at the time of ship-
ment from the factory. Microchip further certifies that its calibration measurements are
traceable to the United States National Institute of Standards and Technology (NIST),
to the extent allowed by the Institute's calibration facility, and to the calibration facilities
of other International Standards Organization members.
1.7.13 Assistance
For complete warranty terms, certifications, product maintenance agreements, and
other customer assistance agreements, please contact your nearest Microchip Sales
and Service Office.

5071A Primary Frequency Standard User’s Guide
DS50003249A-page 19  2022 Microchip Technology Inc.
NOTES:

5071A PRIMARY FREQUENCY
STANDARD USER’S GUIDE
 2022 Microchip Technology Inc. DS50003249A-page 20
Chapter 2. Getting Started
This section introduces the front-panel interface menus and shows how to perform
more complex time-keeping tasks.
2.1 THE 5071A AT A GLANCE
If you've unpacked and inspected the 5071A, and are ready to operate it, see Starting
the 5071A.
The front-panel features are illustrated and briefly described on the following pages.
The item numbers on this page correspond to the callouts in Figure 2-1, Figure 2-2, and
Figure 2-3.
2.1.1 Indicators
• Clock display: Shows 24-hour time.
• Attention light: Indicates power-up sequence or the need for attention (refer to
Troubleshooting Tips for more information).
• Continuous operation light: When lit continuously, indicates normal operation (no
faults since last reset).Refer to Troubleshooting Tips for more information.
• LCD display: Shows instrument menus, functions, MJD, and internal operating
parameters (see Performing Basic Tasks to adjust the LCD display for best view-
ing).
2.1.2 Controls
• Data entry/function keypad: Selects six menu shortcuts and enters numeric data.
• Actions keypad: Controls cursor, menu choices, data entry termination, and dis-
play contrast.
2.1.3 Connectors
• 1PPS output: Provides a 20 µs pulse every second for synchronization and tim-
ing.
• SYNC input: Accepts a 100 ns to 100 µs pulse for synchronization of 1PPS. The
electrical characteristics of these connectors are the same as the rear panel 1PPS
output and sync input. For more information, see Rear Panel Connections.