HP 8556a schematic

TM 11-6625-2781-14&P-5

TECHNICAL MANUAL

OPERATOR'S, ORGANIZATIONAL,

DIRECT SUPPORT, AND GENERAL SUPPORT

MAINTENANCE MANUAL

(INCLUDING REPAIR PARTS AND SPECIAL TOOLS LIST)

FOR

PLUG-IN, LOW FREQUENCY

(SPECTRUM ANALYZER)

PL-1387/U

(HP-8556A)

(NSN 6625-00-167-5267)

HEADQUARTERS, DEPARTMENT OF THE ARMY

27 APRIL 1983

5

1

234

5

SAFETY STEPS TO FOLLOWING SOMEONE IS THE VICTIM OF ELECTRICAL SHOCK

DO NOT TRY TO PULL OR GRAB THE INDIVIDUAL

IF POSSIBLE, TURN OFF THE ELECTRICAL POWER

IF YOU CANNOT TURN OFF THE ELECTRICAL POWER, PULL, PUSH OR LIFT THE PERSON
TO SAFETY USING A DRY WOODEN POLE OR A DRY ROPE OR SOME OTHER INSULATING
MATERIAL

SEND FOR HELP AS SOON AS POSSIBLE

AFTER THE INJURED PERSON IS FREE OF CONTACT WITH THE SOURCE OF ELECTRICAL
SHOCK, MOVE THE PERSON A SHORT DISTANCE AWAY AND IMMEDIATELY START
ARTIFICIAL RESUSCITATION

WARNINGS

Removing the top cover from the Display Section exposes the operator to
dangerous potentials (up to 7000 volts).

INPUT connector ground is isolated from cabinet ground. Any voltage present on
cable shield will be present on connector shell (± 100 VDC maximum). If
contacted, this voltage may cause personal injury.

A

SPECTRUM ANALYZER LF SECTION

8556A

Serials Prefixed: 1104A

This manual applies directly to LF Sections with the serial number prefixes listed above.

Serial Prefixes Not Listed

For LF Sections with serial prefixes not listed, a "Manual Changes" insert is included with
this manual.

Copyright HEWLETT-PACKARD COMPANY 1971

1501 PAGE MILL ROAD, PALO ALTO, CALIFORNIA, U.S.A.

Manual Part No. 08556-90004
Microfiche Part No. 08556-90006 Printed JULY 1971

B

CERTIFICATION

Hewlett-Packard Company certifies that this instrument met its published specifications at
the time of shipment from the factory. Hewlett-Packard Company further certifies that its
calibration measurements are traceable to the United States National Bureau of
Standards, to the extent allowed by the Bureau's calibration facility, and to the calibration
facilities of other International Standards Organization members.

WARRANTY AND ASSISTANCE

This Hewlett-Packard product is warranted against defects in materials and workmanship
for a period of one year from the date of shipment. Hewlett-Packard will, at its option,
repair or replace products which prove to be defective during the warranty period
provided they are returned to Hewlett-Packard, and provided the preventive maintenance
procedures in this manual are followed. Repairs necessitated by misuse of the product
are not covered by this warranty. NO OTHER WARRANTIES ARE EXPRESSED OR
IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. HEWLETT­PACKARD IS NOT LIABLE FOR CONSEQUENTIAL DAMAGES.

If this product is sold as part of a Hewlett-Packard integrated instrument system, the
above warranty shall not be applicable, and this product shall be covered only by the
system warranty.

C/(D blank)

This manual contains copyrighted material reproduced by permission of the Hewlett-Packard Company. All rights
reserved.

TM 11-6625-2781-14&P-5

TECHNICAL MANUAL HEADQUARTERS

DEPARTMENT OF THE ARM Y

No. 11-6625-2781-14 & P-5 Washington, DC, 27 April 1983

OPERATOR'S, ORGANIZATIONAL, DIRECT SUPPORT,

AND GENERAL SUPPORT MAINTENANCE MANUAL,

INCLUDING REPAIR PARTS AND SPECIAL TOOLS LISTS

FOR

PLUG-IN, LOW FREQUENCY

(SPECTRUM ANALYZER)

PL-13871U

(HP-8556A)

(NSN 6625-00-167-5267)

REPORTING ERRORS AND RECOMMENDING IMPROVEMENTS

You can improve this manual. If you find any mistakes, or if you know of a way to
improve the procedures, please let us know. Mail your letter or DA Form 2028
(Recommended Changes to Publications and Blank Forms) directly to:
Commander, US Army Communications-Electronics Command and Fort
Monmouth, ATTN: DRSEL-ME-MP, Fort Monmouth, NJ 07703. In either case a
reply will be furnished directly to you.

TABLE OF CONTENTS

SECTION O INTRODUCTION Page

O-1 Scope .............................................................................................................................O-1

O-2 Index of Publications .............................................................................................O-1

O-3 Maintenance Forms, Records, and Reports ..........................................................O-1

O-4 Reporting Equipment Improvement Recommendations (EIR) ...........................O-1

O-5 Administrative Storage .............................................................................................O-1

O-6 Destruction of Army Electronic Materiel .................................................................O-1

i

TABLE OF CONTENTS

Section Page

I GENERAL INFORMATION..............................................1-1

1-1. Introduction............................................................1-1

1-5. Instruments Covered by Manual.........................1-1

1-7. Description.............................................................1-1

1-15. Accessories Suppl ied...........................................1-2

1-18. Equipment Required but not Supplied...............1-2

1-20. IF Sections .........................................................1-2

1-22. Display Sections................................................1-2

1-24. Compatibility...........................................................1-2

1-27. Operating Accessories .........................................1-2

1-29. Test Equipment Required....................................1-2

1-31. Warranty..................................................................1-2

II INSTALLATION .................................................................2-1

2-1. Initial Inspection.....................................................2-1

2-2. Mechanical Check.............................................2-1

2-4. Electrical Check.................................................2-1

2-6. DELETED...........................................................2-1

2-9. Preparation for Use ..............................................2-1

2-10. Shipping Configuration ....................................2-1

2-12. Power Requirements ........................................2-1

2-15. Power Cable......................................................2-1

2-17. Operating Environment....................................2-1

2-19. Interconnections................................................2-1

2-22. Storage and Shipment .........................................2-2

2-23. Original Packaging............................................2-2

2-27. Other Packaging Materials .............................2-2

III OPERATION ......................................................................3-1

3-1. Introduction............................................................3-1

3-3. Panel Features ......................................................3-1

3-5. Operator's Checks ................................................3-1

3-7. Operating Considerations ....................................3-1

3-9. RF Input..............................................................3-1

3-12. Amplitude Ranges.............................................3-1

3-16. First Mixer Balance ..........................................3-1

3-23. Operating Instructions .........................................3-2

3-26. Setting the Frequency Scan............................3-2

3-31. Adjusting the Amplitude Scale........................3-2

3-37. Using the Tracking Generator.........................3-8

3-52. Variable Persistence and Storage

Functions.........................................................3-10

3-57. Photographic Techniques ...............................3-10

IV PERFORMANCE TESTS

4-1. Introduction............................................................4-1

4-4. Equipment Required.............................................4-1

4-6. Operational Adjustments......................................4-1

4-8. Front Panel Checks .............................................4-1

4-10. Test Sequence......................................................4-1

4-14. Tracking Generator Amplitude............................4-3

4-15. Marker Accuracy ...................................................4-4

4-16. Scan Width Accuracy............................................4-6

4-17. Center Frequency Accuracy................................4-7

4-18. Frequency Response...........................................4-8

4-19. Average Noise Level ............................................4-10

4-20. Residual Responses ............................................4-12

4-21. Spurious Responses ...........................................4-14

4-22. Residual FM...........................................................4-17

4-23. Noise Sidebands ..................................................4-19

4-24. Input Level Control and Gain Compression......4-21

4-25. Tracking Generator Spectral Purity ...................4-23

ii

Section Page

V ADJUSTMENTS................................................................5-1

5-1. Introduction............................................................5-1

5-4. Test Equipment Required ...................................5-1

5-7. Posidriv Screwdrivers .......................................5-1

5-9. Blade Tuning Tools ..........................................5-1

5-11. HP 11592A Service Kit ....................................5-1

5-14. Extender Cable Installation..............................5-1

5-18. Factory Selected Components............................5-1

5-20. Related Adjustments ............................................5-1

5-23. Voltage Checks .....................................................5-2

5-24. Pre-Attenuator Adjustments:

COMP and C IN.................................................5-4

5-25. 50.150 MHz Local Oscillator

Adjustment: A6T1 .............................................5-6

5-26. Mixer Balance Adjustments: C, R and Z............5-7

5-27. Tracking Generator Adjustments:

AMPL ADJ and FLATNESS ADJ ....................5-8

5-28. Frequency Calibration Adjustment:

OFFSET ADJ, 300 kHz ADJ, and

ZERO ADJ .........................................................5-10

5-30. 8552A 47 MHz LO Adjustment ..........................5-13

VI REPLACEABLE PARTS...................................................6-1

6-1. Introduction............................................................6-1

6-5. DELETED...............................................................6-1

VII MANUAL CHANGES

DELETED

VIII SERVICE ...........................................................................8-1

8-1. Introduction............................................................8-1

8-3. Theory of Operation..........................................8-1

8-5. Recommended Test Equipment ....................8-1

8-8. Troubleshooting ................................................8-1

8-13. General Service Information................................8-1

8-14. Part Location Aids.............................................8-1

8-16. Factory Selected Components........................8-1

8-18. Diagram Notes...................................................8-1

8-20. Servicing Aids on Printed Circuit

Boards .............................................................8-2

8-22. Circuit Board Extender ....................................8-2

8-24. General Service Hints ..........................................8-2

8-25. Etched Circuits ..................................................8-2

8-27. Etched Conductor Repair ...............................8-2

8-29. Component Replacement ...............................8-2

8-36. Logic Circuits and Symbols .................................8-5

8-40. Basic AND Gate (Positive Logic)....................8-6

8-42. Basic OR Gate (Positive Logic) .....................8-6

8-45. Truth Tables.......................................................8-6

8-47. Logic Inversion..................................................8-6

8-49. Binary Circuits and Symbols ..............................8-6

8-51. Reset-Set (RS) Flip-Flop..................................8-6

8-53. The RST Flip-Flop.............................................8-8

8-55. Clocked JK Flip-Flop........................................8-8

8-57. JK Master/Slav e Flip-Flop ...............................8-9

8-60. Preset and Clear ..............................................8-10

8-62. Operational Amplifiers ..........................................8-10

8-63. Circuits and Symbols........................................8-10

8-66. Troubleshooting ................................................8-12

8-70. Dial Calibration Procedure...................................8-12

LIST OF ILLUSTRATIONS

Figure Page

1-1 Model 8556A Spectrum A nalyzer LF Section with

8552B IF Section and 141T Display Section ...1-0

1-2 Instrument Identification ..............................................1-1

1-3 Typical Spectrum Analyzer Resolution......................1-6

1-4 Typical Spectrum Analyzer Distortion Products.......1-6

1-5 HP 11592A Service Kit ................................................1-12

2-1 LF Section and IF Section Interconnections ............2-3

3-1 Front Panel Features....................................................3-3

3-2 Operational Adjustments..............................................3-6

3-3 Typical Frequency Response Measurement

(in 50 Ohms) .........................................................3-9

3-4 Typical Amplifier Frequency Response Meas-

urement (in 600 Ohms) using a

Frequency Counter...............................................3-9

4-1 Tracking Generator Test Setup..................................4-3

4-2 Marker Accuracy Test Setup .......................................4-4

4-3 Scan Width Accuracy Display.....................................4-6

4-4 Frequency Response Test Setup ..............................4-8

4-5 Average Noise Level Display ......................................4-11

4-6 Residual Responses Display .......................................4-13

4-7 Spurious Responses Test Setup ................................4-14

4-8 Intermodulation Distortion Products Display.............4-16

4-9 Residual FM Test Setup...............................................4-17

4-10 Residual FM Display.....................................................4-18

4-11 Noise Sidebands Test Setup.......................................4-19

4-12 Noise Sidebands Display.............................................4-20

4-13 Input Level Control and Gain Compression

Test Setup..............................................................4-21

4-14 Tracking Generator Spectral Purity Test Setup .......4-23

5-1 Voltage Checks Test Setup.........................................5-2

5-2 Pre-Attenuator Adjustment Test Setup......................5-4

5-3 50.150 MHz Local Oscillator Adjustment

Test Setup..............................................................5-6

5-4 Mixer Balance Adjustments Test Setup....................5-7

5-5 Tracking Generator Adjustment Test Setup ............5-9

5-6 Frequency Calibration Adjustment Test Setup ........5-10

5-7 47 MHz LO Adjustment Display .................................5-14

6-1 Front Panel Parts, Exploded View..............................6-11

8-1 8556A LF Section with Circuit Board Extended ......8-3

8-2 Examples of Diode and Transistor Marking

Methods..................................................................8-4

8-3 Integrated Circuit Packaging ......................................8-5

8-4 Basic AND and OR Gates ..........................................8-5

8-5 Basic NAND and NOR Gates......................................8-6

8-6 Logic Comparison Diagrams ......................................8-7

8-7 RS Flip-Flop...................................................................8-7

8-8 RST Flip-Flop ................................................................8-8

8-9 The Clocked JK Flip-Flop ...........................................8-9

8-10 JK Master/Slave Flip-Flop ...........................................8-10

8-11 Operational Amplifier Equivalent Circuit ....................8-11

8-12 Dial Restringing Procedure..........................................8-13

8-13 Overall Troubleshooting Tree .....................................8-15

8-14 Top and Bottom Internal Views...................................8-19

8-15 Troubleshooting Block Diagram..................................8-23

8-16 Simplified Analyzer Block Diagram ...........................8-27

Figure Page

8-17 LF Section Block Diagram ...........................................8-27

8-18
8-19 Reserved for Optional Inputs (will not appear in
8-20 this printing).
8-21 Master Board Assembly A11 Component

Locations ...............................................................8-31

8-22 Pre-Attenuator and Preamplifier Assembly A5

Component Locations .........................................8-31

8-23 Pre-Attenuator and Preamplifier: A3, A5 and

All Schematic.........................................................8-31

8-24 Input Level Switch Assembly A3 Component

Locations ...............................................................8-35

8-25 Frequency Converter Assembly A6

Component Locations .........................................8-35

8-26 Post-Attenuator and Frequency Converter:

A3 and A6 Schematic...........................................8-35

8-27 Tracking Generator Frequency Converter

Assembly A9 Component Locations ..................8-39

8-28 Tracking Generator Frequency Converter:

A9 Schematic.........................................................8-39

8-29 Tracking Generator Output Assembly A8

Component Locations .........................................8-43

8-30 3 MHz Oscillator Assembly A8A1

Component Locations .........................................8-43

8-31 Input Level Switch Assembly A3

Component Locations .........................................8-43

8-32 Tracking Generator Output: A3 and A8

Schematic...............................................................8-43

8-33 Integrated Circuit Logic Diagrams .............................8-47

8-34 Frequency Control and Marker Generator

Assembly A7 Component Locations ..................8-47

8-35 20 kHz Marker Circuits: A7 Schematic......................8-47

8-36 Scan Width Switch Assembly A2 Component

Locations ...............................................................8-51

8-37 Frequency Control and Marker Generator

Assembly A7 Component Locations..................8-51

8-38 Frequency Control Circuits:

A1, A2 and A7 Schematic ...................................8-51

8-39 Simplified Analogic Diagram ......................................8-53

8-40 Bandwidth Switch Assembly A1 Component

Locations ...............................................................8-55

8-41 Scan Width Switch Assembly A2 Component

Locations ................................................................8-55

8-42 Analogic Circuits: A1 and A2 Schematic ..................8-55

8-43 Bandwidth Switch Assembly A1

Component Locations .........................................8-59

8-44 Input Level Switch Assembly A3 Component

Locations ...............................................................8-59

8-45 IF Section Control Circuits: A1 and A3

Schematic...............................................................8-59

8-46 Power Supply Assembly A10 Component

Locations ...............................................................8-63

8-47 Master Board Assembly A11 Component

Locations ...............................................................8-63

8-48 Power Supply and Voltage Distribution:

A10 and All Schematic.........................................8-63

iii

LIST OF TABLES

Table Page

1-1 Specifications.................................................................1-3

1-2 Supplemental Performance Character istics .............1-6

1-3 Operating Accessories .................................................1-9

1-4 Test Equipment ............................................................1-9

1-5 Test Equipment Accessories.......................................1-11

4-1 Front Panel Checks .....................................................4-2

4-2 Performance Test Record............................................4-25

5-1 Analogic Display Calibration Check...........................5-12

5-2 Check and Adjustment Test Record..........................5-15

Table Page

6-1 Designators and Abbreviations used in

Parts List .................................................................6-1

6-2 Manufacturers Code List..............................................6-2

6-3 Replaceable Parts.........................................................6-3

8-1 Factory Selected Components....................................8-2

8-2 Etched Circuit Soldering Equipment..........................8-4

8-3 Schematic Diagram Notes ..........................................8-14

8-4 Assembly and Component Locations ........................8-19

8-5 Connector P2 Pin Identification .................................8-21

8-6 Connector P3 Pin Identification .................................8-21

8-7 Connector XA11 Pin Identification.............................8-21

APPENDIXES

APPENDIX A. REFERENCES ......................................................................................................A-1

APPENDIX B. MAINTENANCE ALLOCATION

Section I. Introduction ...........................................................................................................B-1

II. Maintenance Allocation Chart .................................................................................B-3

III. Tool and Test Equipment Requirements ..................................................................B-4

APPENDIX C. COMPONENTS OF END ITEM LIST (Not applicable)

Page

APPENDIX D. ADDITIONAL AUTHORIZATION LIST (Not applicable)
APPENDIX E. EXPENDABLE SUPPLIES AND MATERIA LS (Not applicable)

APPENDIX F. PART NUMBER-NATIONAL STOCK NUMBER INDEX ............................................F-1

APPENDIX G. MANUFACTURER'S ERRATA AND MANUAL CHANGES .......................................G-1

iv

SECTION O

INTRODUCTION

O-1. Scope

This manual provides technical data, and installation,
operation, and maintenance instructions for the
spectrum analyzer low-frequency plug-in PL1387/U,
Hewlett-Packard model 8556A. The PL1387/U is
referred to throughout this manual as the 8556A.
Appendix A lists pertinent publications. Appendix B
contains the Maintenance Allocation Chart (MAC), which
defines the levels and scope of maintenance functions
for the equipment in the Army system, and a list of the
tools and test equipment required. Appendix F provides
a cross reference between commercial part numbers
and National Stock Numbers (NSN). Appendix G
provides a listing of errors in this manual, and changes
which are to be made to the manual, depending on the
serial number of the 8556A with which the manual is to
be used. As indicated, for plug-ins having serial
numbers from 1124A00121, to 1124A00130, only
change 1 is to be applied to the manual. For plug-ins
with serial numbers 1404A2236 and later models, all
nine changes to the manual are required. The list of
appendices is located on page iv, following LIST OF
TABLES in TABLE OF CONTENTS.

O-2. Consolidated Index of Army Publications and

Blank Forms

Refer to the latest issue of DA PAM 310-1 to determine
whether there are new editions, changes or additional
publications pertaining to the equipment.

O-3. Maintenance Forms, Records, and Reports

a. Reports of Maintenance and Unsatisfactory

Equipment. Department of the Army forms and
procedures used for equipment maintenance will be
those prescribed by TM 38-750, The Army Maintenance
Management system.

b. Report of Packaging and Handling Deficiencies.
Fill out and forward SF 364 (Report of Discrepancy
(ROD)) as prescribed in AR 735-11-2/ DLAR

4140.55/NAVMATINST 4355.73/AFR 400-54/MCO

4430.3E.

c. Discrepancy in Shipment Report (DISREP) (SF

361). Fill out and forward Discrepancy in Shipment
Report (DISREP) (SF 361) as prescribed in AR 55-38
NAVSUPINST 4610.33B AFR 75-18./MCO P

4610.19C/DLAR 4500.15.

O-4. Reporting Equipment Improvement

Recommendations (EIR)

If your plug in 8556A needs improvement, let us know.
Send us an EIR. You, the user, are the only one who
can tell us what you don't like about your equipment. Let
us know why you don't like the design. Put it on an SF
368 (Quality Deficiency Report). Mail it to: Commander,
US Army Communications-Electronics Command and
Fort Monmouth, ATTN; DRSEL-ME-MP, Fort Monmouth,
NJ 07703. We'll send you a reply.

O-5. Administrative Storage

The 8556A plug-in can be stored in stockrooms,
warehouses, or other protected facilities. The equipment
should be protected from excessive humidity, sand, dust,
and chemical contaminants. Before putting the 8556A in
administrative storage, make the following preparations:

a. Complete the operational adjustments

procedure given in figure 3-2 to assure that the plug-in is
operable.

b. If the original packing material is not available, at
least protect the unit with protective plastic or paper
wrapping. Place the unit in a carton or box with

makeshift protective packing material around it.

c. Store the equipment indoors, protected from the
elements. Maintain the equipment at moderate
temperature and humidity.

O-6. Destruction of Army Electronic Materiel

Destruction of Army electronic materiel to prevent enemy
use shall be in accordance with TM 750-244-2.

O-1

General Information Model 8556A

MODEL 8556A

1-0

Figure 1-1. Model 8556A Spectrum Analyzer LF Section with 8552B IF Section and 141T Display Section

Model 8556A General Information

SECTION I

GENERAL INFORMATION

1-1. INTRODUCTION

1-2. This manual contains all information required to
install, operate, test, adjust and service the Hewlett­Packard Model 8556A Spectrum Analyzer LF Section.
This section covers instrument identification, description,
options, accessories, specifications and other basic
information.

1-3. Figure 1-1 shows the Hewlett-Packard Model
8556A Spectrum Analyzer LF Section with the Model
8552B Spectrum Analyzer IF Section and the Model
141T Display Section. Also shown are the accessories
supplied with the 8556A (see paragraph 1-15).

1-4. The various sections in this manual provide
information as follows:

SECTION II, INSTALLATION, provides
information relative to incoming inspection,
power requirements, mounting, packing,
shipping, etc.

SECTION III, OPERATION, provides information
relative to operating the instrument.

SECTION IV, PERFORMANCE TESTS,
provides information required to ascertain that
the instrument is performing in accordance with
published specifications.

SECTION V, ADJUSTMENTS, provides
information required to properly adjust and align
the instrument after repairs are made.

SECTION VI, REPLACEABLE PARTS, provides
ordering information for all replaceable parts and
assemblies.

SECTION VII, MANUAL CHANGES, normally
will contain no relevant information in the original
issue of a manual. This section is reserved to
provide back-dating and up-dating information in
manual revisions or reprints.

SECTION VIII, SERVICE, includes all
information required to repair the instrument.

1-5. INSTRUMENTS COVERED BY MANUAL

1-6. Hewlett-Packard instruments carry a serial number
(see Figure 1-2) on the back panel. When the serial

number prefix on the instrument serial number plate of
your instrument is the same as one of the prefix
numbers on the inside title page of this manual, the
manual applies directly to the instrument. When the
instrument serial number prefix is not listed on the inside
title page of this manual, manual change sheets and
manual updating information is provided. Later editions
or revisions to the manual will contain the required
change information in Section VII.

Figure 1-2. Instrument Identification

1-7. DESCRIPTION

1-8. The Hewlett-Packard Model 8556A Spectrum
Analyzer LF Section covers the frequency range from 20
Hz to 300 kHz. When it is combined with an IF Section
and a Display Section it functions as the tuning section
of a low frequency spectrum analyzer.

1-9. The analyzer electronically scans input signals and
displays their frequency and amplitude on a CRT. The
horizontal, x-axis, is calibrated in units of frequency and
the vertical, y-axis, is calibrated in absolute units of
voltage (pV, mV, dBV) or power (dBm). Therefore,
absolute and relative measurements of both amplitude
and frequency can be made.

1-10. The horizontal (frequency) axis can be swept
three different ways:

a. The center of the CRT is set to a frequency
determined by the dial and the analyzer is swept

symmetrically about that frequency.

b. The analyzer is not swept but is used as a fixed
frequency receiver. Signal amplitude can be read on the
CRT and signal modulation can be viewed as with an

oscilloscope.

1-1

General Information Model 8556A

c. The analyzer is swept from 0 Hz to a higher

frequency selectable from 200 Hz to 200 kHz.

1-11. The vertical (amplitude) axis provides relative and
absolute measurement capability in volts, dBV, dBm into
600 ohms unbalanced, and dBm into 50 ohms.

1-12. The LF Section's input is isolated from the
instrument chassis so that the CRT display is free of line
frequency spurious responses due to ground loops.

1-13. Accurate frequency calibration is provided by
selecting 20 kHz markers.

1-14. The LF Section also contains a tracking generator
that produces a calibrated signal that precisely tracks the
analyzer tuning frequency. This signal can be used to
test the frequency response of a device; it can also be
used, with a frequency counter, for making frequency
measurements that are accurate to 1 Hz (see Section
III).

1-15. ACCESSORIES SUPPLIED

1-16. The 8556A LF Section requires a special knob on
the IF Section in place of the standard LOG REF LEVEL
control. The special knob has three scales: one is used
for the LF Section log calibration (red scale), one for log
calibration with the RF Sections (black scale), and one
for linear calibration with all units (blue scale). This knob
and an allen wrench to install it are supplied with each
8556A. Extra knobs (HP 08556-00013) are available.

1-17. The 8556A is supplied with the following
accessories: HP 11095A 600 ohm Feed Thru
Termination
HP 11048C 50 ohm Feed Thru Termination
HP 11660A Tracking Generator Shunt (50
ohm output)

1-18. EQUIPMENT REQUIRED BUT NOT SUPPLIED

1-19. The 8556A LF Section must be mated with an IF
Section, such as the 8552A or the 8552B, and a Display
Section, such as the 140T or the 141T, before the units
can perform as a spectrum analyzer.

1-20. IF Sections

greater frequency stability, narrower bandwidths and an
expanded log scale (2 dB per division).

1-22. Display Sections

1-23. The 140T Display Section is equipped with a fixed
persistence, non-storage CRT; the 141T Display Section
is equipped with a variable persistence, storage CRT.
The 143S Display Section has a large screen (8x10
inch) CRT.

1-24. COMPATIBILITY

1-25. The 8556A LF Section is fully compatible with all
current 8552A/B IF Sections; 8552A's with serial prefix
991 and below, and 8552B's with serial prefix 977 and
below must be modified. The modification consists of
adding a white-blue-grey (24 AWG) wire between
8552A/B connectors XA8 pin 8 and J3 pin 40. (See
appropriate 8552 manual for location of connectors.)

NOTE

The 8556A requires a special knob on
the IF Section in place of the
standard LOG REF LEVEL control
(see EQUIPMENT SUPPLIED).

1-26. The 8556A LF Section is fully compatible with all
HP 140S/T, HP 141S/T, and HP 143S Display Sections.
The 8556A can be used with HP 140A/B and 141A/B
Oscilloscope Mainframes but some performance
specifications will be slightly degraded. (For more
information, contact your nearest Hewlett-Packard
office.)

1-27. OPERATING ACCESSORIES

1-28. Operating accessories for use with the
8556A]8552/140 Spectrum Analyzer are listed in Table
1-3. They include a frequency counter, an oscilloscope
camera, and various attenuators and probes.

1-29. TEST EQUIPMENT REQUIRED

1-30. Tables 1-4 and 1-5 list the test equipment and test
equipment accessories required to check, adjust and
repair the 8556A LF Section.

1-21. The 8552A IF Section features calibrated
bandwidths, log and linear amplitude calibration, and
calibrated scan times. The 8552B IF Section has all of
the features of the 8552A and, in addition, manual scan,

1-2

1-31. WARRANTY

1-32. The 8556A LF Section is warranted and certified
as indicated on page C.

Model 8556A General Information

Table 1-1. Specifications

8556A/8552B/8552A

FREQUENCY

Range:

20 Hz to 300 kHz - 8552B IF Sec tion
100 Hz to 300 kHz - 8552A IF Section

Tuning Dial Ranges of 0-30 kHz and 0-300 kHz.

Scan Width: (On a 10 div. CRT horizontal axis.)

Per Division: 10 calibrated scan widths from 20 Hz/div

to 20 kHz/div in a 1,2, 5 sequence.

0-10f: 10 calibrated preset scans, from 200 Hz to 200
kHz in a 1, 2, 5 sequence. Analyzer scans from zero
frequency to ten times the scan width per division
setting.

Zero: Analyzer is a fixed tuned receiver.

Accuracy:

Center Frequency: After 1 hour warmup, zero and 300

kHz adjustments, and with the Fine Tune centered,
the dial indicates the display center frequency within
the following specifications:

With 8552B IF Section:

0-30 kHz Range: ±500 Hz
0-300 kHz Range: ±3 kHz

Stability:

Residual FM:
With 8552B IF Section:

Sidebands >60 dB down 50 Hz or more from CW
signal, scan time ≥1 sec/div, 10 Hz band width.

With 8552A IF Section:

Less than 20 Hz peak-to-peak.

Noise Sidebands: More than 90 dB below CW signal,

3 kHz away from signal, with a 100 Hz IF bandwidth.

Frequency Drift: (After 1 hour warmup.)

With 8552B IF Section: Less than 200 Hz/10 min.
With 8552A IF Section: Less than 1 kHz /10 min.

Resolution:

Bandwidth Ranges: IF bandwidths of 10 Hz (50 Hz for

8552A) to 10 kHz are provided in a 1, 3, 10
sequence.

With 8552A IF Section:

0-30 kHz Range: ±1 kHz
0-300 kHz Range: ±5 kHz

Marker: RF markers every 20 kHz accurate to within

±0.01%. Markers controlled by front panel on/off
switch.

Scan Width:

With 8552B IF Section:

Frequency error between any two points on the
display is less than ±3% of the indicated frequency

separation.

With 8552A IF Section:

Frequency error between any two points on the
display is less than ±5% of the indicated frequency
separation.

Bandwidth Accuracy: Individual IF bandwidth 3 dB

points calibrated to ±20% (10 kHz band width ±5%).

Bandwidth Selectivity: 60 dB/3 dB IF bandwidth ratios.

With 8552B IF Section: <11:1 for IF bandwidths from

30 Hz to 3 kHz; <20:1 for 10 kHz IF bandwidth. For
10 Hz bandwidth, 60 dB points are separated by
less than 100 Hz.

With 8552A IF Section: <25:1 for IF bandwidths from

50 Hz to 300 Hz; <20:1 for IF bandwidths from 1 kHz
to 10 kHz.

1-3

General Information Model 8556A

Table 1-1. Specifications (cont'd)

AMPLITUDE

Absolute Amplitude Calibration Range:

Log Modes:

dBV 0 dBV = 1 V rms
dBm-600Ω 0 dBm = 1 mW - 600Ω
dBm-502Ω 0 dBm = 1 mW - 502Ω

Input impedance is 1 MΩ. dBm ranges are referenced
with input properly terminated externally.

Log Range: From -150 dBm/dBV to +10 dBm/dBV in

10 dB steps. Log reference level vernier, 0 to -12
dB continuously.

Log Display Range: 10 dB/div on a 70 dB display, or 2

dB/div on a 16 dB display (with 8552B only).

Linear Sensitivity: From 0.1 µV/div to 1V/div in a 1, 2,

10 sequence. Linear sensitivity vernier X1 to X0.25
continuously.

Dynamic Range :

Average Noise Level: Specified with a 600Ω or less

source impedance and INPUT LEVEL at -60
dBm/dBV.

1 kHz IF 10 Hz IF

Mode Bandwidth Bandwidth

dBm-50 Ω <-122 dBm (180 nV) <-142 dBm (18 nV)
dBm-600Ω <-130 dBm (250 nV) <-150 dBm (25 nV)
dBV <-132 dBV (250 nV) <-152 dBV (25 nV)
Linear <400 nV <40 nV

Spurious Responses: Input signal level ≤ INPUT LEVEL

Setting: out of band mixing responses,

TRACKING GENERATOR

harmonic and intermodulation distortion products are
all more than 70 dB below the input signal level 5
kHz to 300 kHz; 60 dB 20 Hz to 5 kHz. Third order
intermodulation products are more than 70 dB below
the input signal level, 5 kHz to 300 kHz with signal
separation >300 Hz.

Residual Reponses: (no signal present at input): with

the INPUT LEVEL at -60 dBm/dBV and the input
terminated with 600Ω or less, all line related residual

responses from 0-500 Hz are below -120 dBm/dBV.
All other residual responses are below -130
dBm/dBV.

Gain Compression: For input signal level 20 dB above

INPUT LEVEL setting gain compression is less than
1 dB.

INPUT LEVEL Control: -10 to -60 dBm/dBV in 10 dB

steps. Accuracy ±0.2 dB. Marking indicates
maximum input levels for 70 dB spurious-free
dynamic range.

Accuracy:

Log Linear

Frequency Response: ±0.2 dB ±2.3%
Switching Between
Bandwidths (at 20°C),

100 Hz to 10 kHz: ±0.5 dB ±5.8%

30 Hz to 10 kHz: ±1.0 dB +12%
10 Hz to 10 kHz: ±1.5 dB ±20%

Display: ±.25 dB/dB ±2.8% of full

but not more 8 div display
than ±1.5 dB
over 70 dB
display range

Frequency Range: Tracks the analyzer tuning, 20 Hz to

300 kHz.

Amplitude Range: Continuously variable from 100 mV

rms to greater than 3V rms into an open circuit.

Amplitude Accuracy: With TRACKING GEN LEVEL in

CAL position, output level at 100 kHz is 100 mV ±0.3
dB into an open circuit.

Frequency Response: ±0.25 dB 50 Hz to 300 kHz.

1-4

Output Impedance: 600Ω.
Spectral Purity:

Residual FM:

With 8552B IF Section: <1 Hz peak-to-peak.

With 8552A IF Section: <20 Hz peak-to-peak.
Harmonic Signals: >40 dB down.
Spurious Outputs: >50 dB down.

Model 8556A General Information

Table 1-1. Specifications (cont'd)

INPUT

Input Impedance : 1 MΩ shunted by ≈ 32 pF.
Maximum Input Level: 10V rms, ±200 Vdc.

Ground terminals of BNC input connectors are isolated
from the analyzer chassis ground to minimize ground
loop pickup at low frequencies.

Scan Time: 16 internal scan rates from 0.1 ms/div to 10

sec/div in a 1, 2,5 sequence.

Scan Time Accuracy:

0.1 ms/div to 20 ms/div: ±10%
50 ms/div to 10 sec/div: ±20%.

Power Requirements: 115 or 230 volts ±10%, 50 to 60

Hz, less than 225 watts.

Dimensions:

Model 140T or 141T Display Section: 9-1/5" high

(including height of feet) x 16-3/4" wide x 18-3/8"
deep (229 x 425 x 467 mm).

Model 143S Display Section: 21" high (including height

of feet) x 16-3/4" wide x 18-3/8" deep (533 x 425 x
467 mm).

Maximum Voltage. Isolated Ground to Chassis Ground:
±100 Vdc.

Isolated Ground to Chassis Ground Impedance: 100 kΩ
shunted by approximately 0.3 µf.

GENERAL

Weight:

Model 8556A LF Section: Net. 8 lb (3,7 kg).
Model 8552B IF Section: Net. 9 lb (4,1 kg).
Model 8552A IF Section: Net. 9 lb (4,1 kg).
Model 140T Normal Persistence Display Section: Net

37 lb (16,8 kg).
Model 141T Variable Persistence Display Section:

Net, 40 lb (18 kg).
Model 143S Large Screen Display Section: Net 62 lb

(28,1 kg).

Accessories Included:

Model 11660A Tracking Generator Shunt
Model 11048B 50Ω Feed Thru Termination
Model 11095A 600Ω Feed Thru Termination

1-5

General Information Model 8556A

Table 1-2. Supplemental Performance Characteristics

FREQUENCY CHARACTERISTICS

Range: With 300 kHz Center Frequency and 20 kHz/div

Scan Width, analyzer will scan linearly to 400 kHz.

Center Frequency Control: Approximately 10 turns to

cover full dial indicator in both 0-30 kHz and 0-300 kHz
ranges.

Fine Tune: Single turn control, ±50 Hz on 0-30 kHz

range, ±500 Hz on 0-300 kHz range.

Zero Adjust: ±40 kHz range with 8552A, ±12 kHz range

with 8552B.

0-10f Scan Mode: With zero properly adjusted in PER

DIVISION scan, 0 to 10f scan mode will scan from 0
(±500 Hz or 0.2 div, whichever is greater) to ten times
the scan width per division setting. Offset may be
reduced to 0 readjusting frequency zero. Scan
accuracy ±5%.

AMPLITUDE CHARACTERISTICS

Dynamic Range : For operation from 5 kHz to 300 kHz

with signal levels greater than INPUT LEVEL setting,
see Figure 1-4 for typical distortion.

Accuracy:

Resolution: See Figure 1-3 for curves of typical

8556A/8552B/8552A Spectrum Analyzer resolution
using different IF bandwidths. free dynamic range.

Warmup Drift: (Typical - first hour's operation.)

With 8552B: 500 Hz
With 8552A: 15 kHz

Long Term Drift: (Typical - at fixed center frequency

after one hour warmup.)
With 8552B: 70 Hz/10 min

With 8552A: 400 Hz/10 min

Temperature Drift: (Typical.)

With 8552B: 200 Hz/°C
With 8552A: 2 kHz/°C

Input Level: Provides 50 dB control of input
preamplification and attenuation to prevent input
overload. INPUT LEVEL markings of -60 dBm/dBV to ­10 dBm/dBV indicate maximum input level for a
minimum of 70 dB spurious

Log Reference Level: INPUT LEVEL and LOG REF
LEVEL controls provide continuous log reference levels
from +10 dBm/dBV to -80 dBm/dBV (may be decreased
to -92 dBm/dBV by using 12 dB Log Reference Level
Vernier).

Figure 1-3. Typical Spectrum Analyzer

1-6

Signal Level dB Above INPUT LEVEL Setting

* Single input signal, 300 Hz to 300 kHz. Second

and third harmonic distortion products typically 10
dB higher below 30 Hz.

** Two input signals, 5 kHz to 300 kHz with > 300 Hz

signal separation.

*** Two input signals, frequency below 5 kHz with

<300 Hz signal separation.

Figure 1-4. Typical Spectrum Analyzer Distortion

Products

Model 8556A General Information

Table 1-2. Supplemental Performance Characteristics (cont'd)

AMPLITUDE CHARACTERISTICS (cont'd)

Accuracy ±0.2 dB (2.3%). Input may be overloaded
up to 20 dB with the analyzer still providing useful
measurement capability. See Figure 1-4.

Log Reference Level Control: Provides 90 dB of IF

gain control in 10 dB steps to cover log and linear
ranges. Accurate to ±0.2 dB (±2.3%).

Log Reference Level Vernier: Provides continuous 12

dB range. Accurate to ±0.1 dB (±1.2%) in 0, -6, -12
dB positions: otherwise ±0.25 dB (±2.8%).

Log Reference Level, switching between 10 dB/div

and 2 dB/div log scales (8552B only):

DISPLAY CHARACTERISTICS

Variable Persistence/Storage (Model 141T):

Plug-ins: Accepts Model 8550 series Spectrum

Analyzer plug-ins and Model 1400 series time
domain plug-ins.

Cathode-ray Tube:

Type: Post-accelerator storage tube, 9000 volt

accelerating potential; aluminized P31 phosphor:
etched safety glass faceplate reduces glare.

Graticule: 8 x 10 division (approximately 7,1 x 8.9 cm)

parallax-free internal graticule: five subdivisions per
major division on horizontal and vertical axes.

Persistence:

Normal: Natural persistence of P31 phosphor

(approximately 0.1 second).

Variable:

Normal Writing Rate Mode: Continuously variable

from less than 0.2 second to more than one
minute (typically to two or three minutes).

Maximum Writing Rate Mode: Typically from 0.2

second to 15 seconds.

Erase: Manual: erasure takes approximately 350 ms;

CRT ready to record immediately after erasure.

Storage Time: Normal writing rate; more than 2 hours at

reduced brightness (typically 4 hours). More than one
minute at maximum brightness.

Accuracy: ±0.6 dB
Temperature Stability: ±0.07 dB/°C.

Amplitude Stability: ±0.07 dB/°C in log. ±0.6 %°C in

linear.

Display Uncalibrated Light: Warns if a combination of

control settings (IF or video bandwidth, scan time or
scan width) degrades absolute calibration for CW
signals. Typically accurate to ±1 position in scan width
or scan time setting.

Video Filter: Averages displayed noise: bandwidth of 10

kHz, 100 Hz and (8552B only) 10 Hz. Bandwidth
accuracy ±20%.

Fast Writing Speed: More than 15 minutes (typically 30

minutes) at reduced brightness or more than 15

seconds at maximum brightness.
Functions Used with Time Domain Plug-ins Only:

Intensity modulation, calibrator, beam finder.

Normal Persistence (Model 140T):

Plug-ins: Same as 141T.
Cathode-ray Tube:

Type: Post-accelerator. 7300 volt potential medium-

short persistence (P7) phosphor, tinted and etched
safety glass face-plate reduces glare. (Normal
persistence of P7 phosphor approximately 3 sec.)

Graticule: 8 x 10 division (approximately 7,6 x 9,5

cm) parallax-free internal graticule: five
subdivisions per major division on horizontal and
vertical axes.

Functions Used with Time Domain Plug-ins Only:

Same as 141T.

Normal Persistence Large Screen Display (Model
143S):

Plug-ins: Same as 141T.
Cathode Ray Tube:

Type: Post-accelerator. 20 kV accelerating
potential aluminized P31 phosphor. (Persistence
approximately 0.1 sec).
Graticule: 8 x 10 divisions (approximately 8 x 10­inch) parallax-free internal graticule. five
subdivisions per major division on horizontal and
vertical axes.

Functions Used with Time Domain Plug-ins Only:

Same as 141T.

1-7

General Information Model 8556A

Table 1-2. Supplemental Performance Characteristics (cont'd)

GENERAL CHARACTERISTICS

Scan Mode:

Int: Analyzer repetitively scanned by internally

generated ramp; synchronization selected by scan
trigger.

Single: Single scan with reset actuated by front panel

pushbutton.

Ext: Scan determined by 0 to +8 volt external signal;

scan input impedance more than 10 kΩ.
Blanking: -1.5V external blanking signal required.
Manual: Scan determined by front panel control;

continuously variable across CRT in either direction

(8552B only).

Scan Trigger: For Internal Scan Mode, select between:

Auto: Scan free runs.
Line: Scan synchronized with power line frequency.
Ext: Scan synchronized with more than 2 volt (20 volt

max.) trigger signal (polarity selected by internally

located switch in Model 8552 IF Section).
Video: Scan internally synchronized to envelope of RF

input signal (signal amplitude of 1.5 major divisions

peak-to-peak required on display section CRT).

Auxiliary Outputs:

Vertical Output: Approximately 0 to -0.8V for 8 division

deflection on CRT display; approximately 100Ω
output impedance.

Scan Output: Approximately -5 to +5V for 10 div CRT

deflection, 5k Ω output impedance.

Pen Lift Output: 0 to 14V (0V, pen down). Output

available in Int and Single Scan modes and Auto,
Line, and Video Scan Trigger.

CRT Baseline Clipper: Front panel control adjusts

blanking of CRT trace baseline to allow more detailed
analysis of low repetition rate signals and improved
photographic records to be made.

EMI: Conducted and radiated interference is within

requirements of MIL-I-16910C and MIL-I-6181D and
methods CE03 and RE02 of MIL-STD-461 (except 35
to 40 kHz) when 8556A and 8552B are combined in a
140T or 141T Display Section.

1-8

Temperature Range: Operating, 0°C to +55°C,

storage, -40 °C to +75°C.

Model 8556A General Information

Table 1-3. Operating Accessories

Model Number Description

HP 10004A 10:1 Divider Probe (oscilloscope type)

HP 1001A Probe to BNC Adapter

HP 1110A Current Probe: Sensitivity: 1 mV/mA

Bandwidth: 1700 Hz (3 dB down)

30 MHz(3 dB down)

Electronic Counter

HP 5381A Frequency Range: 10 Hz to 80 MHz

Sensitivity: 25 mV Input Impedance: 1 Megohm
Gate Time: 0.1, 1 and 10 sec.
Resolution: 1 Hz
Readout: 7 digits

HP 4437A 600 ohm Unbalanced Attenuator

Range: 0-119.9 dB in 0.1 dB increments
Accuracy: ± 0.2 dB to 90 dB

± 0.5 dB to 110 dB
± 1.0 dB to 119.9 dB

Input Power: 1 watt max

HP 197A Oscilloscope Camera

Table 1-4. Test Equipment

Item Minimum Specifications Suggested Use*

Model

AC Voltmeter Voltage Range: 1 mV to 10V full scale (-10 to +2 dB HP 400EL P,A,T

on dB scale)
Frequency Range: 20 Hz to 400 kHz
Accuracy: ± (2.5% of full scale +2.5% of reading)
AC to DC Converter Output: 1V dc for full scale

meter deflection
AC to DC Converter Accuracy: ± (1% of full scale
+1% of reading)
Input Impedance: 10 MΩ shunted by ≈ 25 pF

Oscilloscope Frequency Range: dc to 50 MHz HP 180A/ A, T

AC or DC Coupling 1801A/
Sensitivity: 0.005 V/DIV 1820B
Voltage Accuracy: ±3%

X10 Oscillo­scope Probe (2) Division Accuracy: 3%

Resistance: 10 MΩ shunted by 10 pF

*Use: Performance = P: Adjustment = A; Troubleshooting = T

HP 10004A A, T

1-9

General Information Model 8556A

Table 1-4. Test Equipment (cont'd)

Item Minimum Specifications Suggested Use*

Model
Frequency Range: 0-60 MHz HP 5327C P, A, T
Counter Sensitivity: 0.1V rms sine wave

Display: 7 digits

Accuracy: ±0.001%
Digital Display: 4 digits HP 3480B, P, A, T
Voltmeter Range: 0 to 100.0 V full scale 3484A
(2 required) 0 to 1000.0 K ohms full scale Opt. 042
for perfor- Accuracy: ± (0.02%7 of reading + 0.05% of range)
mance tests) Polarity: automatic indication
L-C Meter Range: 10 to 40 pF Tektronix A

Accuracy: within 3% of full scale Type 130
Test Oscillator Frequency Range: 20 Hz to 300 kHz HP 651B P, A, T

Dial Accuracy: ±3%

Max Output: > 3.0V into 50 or 600 ohms

Flatness: ± 3%

Distortion: < 1%

Output Monitor: voltmeter monitors output level at

input of attenuator in volts or dB; accurate to ±2%C,
of full scale

Attenuator: range, 90 dB in 10 dB steps

accuracy, ± 0.075 dB, -60 dBm to
+20 dBm

Oscillator Frequency Range: 30 Hz to 100 Hz HP 204D P

Dial Accuracy:± 3%

Max Output: 2.5 V into 600 ohms

Distortion: 0.1% ( 60 dB)

Hum and Noise: <0.01% of output
Filter Set Selectable 500 Hz and 50 kHz Bandpass Filters: White P

> 30 dB of attenuation to second harmonic: Model 2640
> 40 dB of attenuation to third and higher
harmonics

Spectrum HP 8556A/ P
Analyzer 8552B/141T
Only

1-10

*Use: Performance = P: Adjustment A. Troubleshooting = T

General Information Model 8556A

Table 1-5. Test Equipment Accessories

Item Minimum Specifications Suggested Use*

Model
BNC Tee One BNC male, two BNC female connectors HP 1250-0781 P
Adapter Selectro Plug to BNC Jack HP 1250-1236 A, T
Adapter Selectro Jack to BNC Jack HP 1250-1237 A, T
Adapter UHF Plug to BNC Jack (UG-273/U) HP 1250-0071 A
Cable Assy Male BNC to Dual Banana Plug, 45 inches long HP 11001A P
Cable Assy Male BNC Connectors, 24 inches long HP 11086A A
Cable Assy Dual Banana Plugs, 44 inches long HP 11000A P
Cable Assy(2) Male BNC Connectors, 48 inches long HP 10503A P, A, T
Cable Assy Dual Banana Plug to Alligator Clips, 5 feet long HP 11002A A, T
Extender 10 Pins, 20 Conductors, for plug-in circuit boards HP 5060-0256 A, T
Board
Screwdrivers Phillips No. 1 A, T

Phillips No. 2 A, T
Pozidriv No. 1 (Stanley No. 5531) HP 8710-0899 A, T

Pozidriv No. 2 (Stanley No. 5332) HP 8710-0900 A, T
Tuning Tool Non-Metallic Shaft (J.F.D. Model No. 5284) HP 8710-1010 A
50-Ohm Supplied with 8556A HP 11048B P, A, T

Feed Thru
Termination
600-Ohm Supplied with 8556A HP 11095A P, A, T
Feed Thru
Termination
Tracking Supplied with 8556A HP 11660A P
Gen Shunt
Service Kit Contents: HP 11592A A, T

Display Section to Spectrum Analyzer Extender

Cable Assembly (HP 11592-60015)

Tuning Section to IF Section Interconnection

Cable Assembly (HP 11592-60016)

Selectro Female to BNC Male Test Cable ,3 each,

36 inches long (HP 11592-60001)

Selectro Male to Selectro Female Test Cable,

2 each, 8 inches long (HP 11592-60003)

*Use: Performance = P: Adjustment =A: Troubleshooting = T

1-11

General Information Model 8556A

Table 1-5. Test Equipment Accessories (cont'd)

Item Minimum Specifications Suggested Use*

Model
Service Kit Selectro Female to Selectro Female Test Cable, HP 11592A A, T
(cont'd) 2 each, 8 inches long (HP 11592-60002)

Extender Board Assembly, 15 pins, 30 conductors,
for plug-in circuit boards (HP 11592-60011)
Fastener Assembly (2 each: HP 11592-2001 and
HP 1390-0170)
Selectro Jack-to-Jack Adapter (HP 1250-0827)
Wrench, open end, 15/16 inch (HP 8710-0946)
BNC Jack-to-OSM Plug Adapter (HP 1250-1200)
OSM Plug-to-Plug Adapter (HP 1250-1158)
Cable Assembly R and P Connector
(HP 11592-60013)

* Use: Performance = P: Adjustment = A: Troubleshooting = T.

1-12

Figure 1-5. HP 11592A Service Kit

Model 8556A Installation

SECTION II

INSTALLATION
2-1. INITIAL INSPECTION

2-2. Mechanical Check

2-3. Check the shipping carton for evidence of damage
immediately after receipt. If there is any visible damage
to the carton, request the carrier's agent be present
when the instrument is unpacked. Inspect the
instrument for physical damage such as bent or broken
parts and dents or scratches. If damage is found refer to
paragraph 2-6 for recommended claim procedures. If
the instrument appears to be undamaged, perform the
electrical check (see paragraph 2-4). The packaging
material should be retained for possible future use.

2-4. Electrical Check

2-5. The electrical check consists of following the
performance test procedures listed in Section IV. These
procedures allow the operator to determine that the
instrument is, or is not, operating within the
specifications listed in Table 1-1. The initial performance
and accuracy of the instrument are certified as stated on
the inside front cover of this manual. If the instrument
does not operate as specified, refer to paragraph 2-6 for
the recommended claim procedure.

2-6.

2-7. DELETED

WARNING
INPUT connector ground is isolated from cabinet
ground. Any voltage present on cable shield will be
present on connector shell (± 100 VDC maximum). If
contacted, this voltage may cause personal injury.

together, electrically connected and inserted in a display
section or oscilloscope mainframe of the 140-series. For
mechanical and electrical connections, refer to Figure
2-1 and paragraph 2-20.

2-12. Power Requirements

2-13. The Spectrum Analyzer can be operated from a
50 to 60 hertz input line that supplies either a 115 volt or
230 volt (±10% in each case) power. Consumed power
varies with the plug-ins used but is normally less than
225 watts. Line power enters the Display Section or
Mainframe, where it is converted to dc voltages, and
then is distributed to the LF and IF Sections via internal
connectors.

2-14. The 115/230 power selector switch at the rear of
the Display Section must be set to agree with the
available line voltage. If the line voltage is 115 volts, the
slide switch must be positioned so that 115 is clearly
visible. The instrument is internally fused for 115 volt
operation, when shipped. If 230 volt source is to be
used, refer to fuse replacement procedures in the
Display Section manual.

2-8.

2-9. PREPARATION FOR USE

CAUTION
Before applying power, check the
rear panel slide switch on the Display
Section for proper position (115 or
230 volts).

2-10. Shipping Configuration

2-11. Because of individual customer requirements,
shipping configurations are flexible. Preparation for use
is based on the premise that the LF and IF Sections are
installed in a Display Section; thus, the Spectrum
Analyzer is physically and functionally complete for use.
Since the LF and IF Sections are usually received
separately, the plug-ins must be mechanically fitted

2-15. Power Cable

2-16. To protect operating personnel, the National
Electrical Manufacturers Association (NEMA) and the
International Electrotechnical Commission (IEC)
recommends that the instrument panel and cabinet be
grounded. The Spectrum Analyzer is equipped with a
three-conductor power cable: the third conductor is the
ground conductor, and when the cable is plugged into an
appropriate receptacle, the instrument is grounded. To
preserve the protection feature when operating the
instrument from a two-contact outlet, use a three-prong
to two-prong adapter and connect the green lead on the
adapter to ground.

2-17. Operating Environment

2-18. The Spectrum Analyzer uses a forced-air cooling
system to maintain required operating temperatures
within the instrument. The air intake and filter are
located on the rear of the Display Section; air is
exhausted through the side panel perforations.

2-1

Installation Model 8556A

When operating the instrument, choose a location
which provides at least three inches of clearance around
the rear and both sides. Refer to the Display Section
manual for maintenance instructions for the cooling
system.

2-19. Interconnections

2-20. The LF and IF Sections are normally shipped
separately; the plug-ins must be mechanically fitted
together, electrically connected, and then inserted in the
Display Section or mainframe. To make these
connections, refer to Figure 2-1 and proceed as follows:

a. Set the IF Section on a level bench. Locate slot

near right rear corner of LF Section: also, locate metal
tab on IF Section that engages with this slot.

b. Grasp the 8556A LF Section near middle of
chassis and raise until it is a few inches above the IF
Section.

c. Tilt LF Section until front of assembly is about 2
inches higher than the rear.

d. Engage assemblies in such a way that metal tab
on the rear of the IF Section slips through the slot on LF
Section.

e. With the preceding mechanical interface
completed, gently lower LF Section until electrical plug
and receptacle meet.

a. Push front panel latch in direction of arrow until it

releases.

b. Firmly grasp the middle of latch flange and pull

LF/RF Sections straight out.

c. Locate black press-to-release level near right
front side of LF Section. Press this lever and
simultaneously exert an upward pulling force on front
edge of LF Section.

d. When the two sections separate at the front,
raise LF Section two or three inches and slide metal tab
at rear of IF Section out of the slot in which it is engaged.

2-22. STORAGE AND SHIPMENT

2-23. Original Packaging

2-24. The same containers and materials used in
factory packaging may be used.

2-25. If the instrument is being returned to Hewlett­Packard for servicing, attach a tag indicating service
required, return address, instrument model number and
full serial number. Mark the container FRAGILE to
assure careful handling.

2-26. In any correspondence refer to the instrument by
model number and full serial number.

2-27. Other Packaging Materials

f. Position LF Section as required to mate the plug

and receptacle. When plug and receptacle are properly
aligned, only a small downward pressure is required to
obtain a snug fit.

g. After the LF and IF Sections are joined

mechanically and electrically, the complete assembly is
ready to insert in the Display Section.

h. Pick up the LF/IF Sections and center in
opening of Display Section. Push forward until assembly
fits snugly into Display Section.

i. Push in front panel latch to securely fasten

assembly in place.

2-21. To separate the LF/IF Sections from Display
Section and to separate the LF Section from the IF
Section, proceed as follows:

2-2

2-28. The following general instructions should be
followed when repackaging with commercially available
materials:

a. Wrap the instrument in heavy paper or plastic.
If shipping to a Hewlett-Packard Service Office or Center
attach a tag indicating the type of service required,
return address, model number and full serial number.)

b. Use a strong shipping container. A double wall
carton made of 350 pound test material is adequate.

c.Use enough shock-absorbing material (three to four­inch layer) around all sides of the instrument to provide
firm cushion and prevent movement inside the container.

Protect the control panel with cardboard.

d. Seal the shipping container securely.

e. Mark the shipping container FRAGILE to assure
careful handling.

Model 8556A Installation

Figure 2-1. LF Section and IF Section Interconnections

2-3/2-4

Model 8556A Operation

SECTION III

OPERATION

3-1. INTRODUCTION

3-2. This section provides complete operating
instructions for the HP 8556A Spectrum Analyzer LF
Section as used with an 8552 series IF Section and a
140 series Display Section.

3-3. PANEL FEATURES

3-4. Front panel controls, indicators and connectors are
shown and briefly described in Figure 3-1. Rear panel
controls and connectors are shown and described
in Figure 3-2. For a detailed description of IF Section
and Display Section controls and indicators, refer to their
manuals.

3-5. OPERATOR'S CHECKS

3-6. Upon receipt of the analyzer, or when any plug-in is
changed, perform the operational adjustments listed
in Figure 3-2. This procedure corrects for minor
differences between units and ensures that the LF
Section, IF Section and Display Section are properly
matched.

3-7. OPERATING CONSIDERATIONS

3-8. Front panel controls, indicators and connectors are
shown and briefly described in Figure 3-1. The following
information covers general operating considerations.

3-9. RF Input

3-10. The 8556A has an input impedance of 1 Megohm,
shunted by approximately 32 pF, so compensated
oscilloscope probes (see Table 1-3) can be connected
directly to INPUT and used for in-circuit testing. To
compensate an oscilloscope probe for use with the
8556A, use the probe's BNC adaptor to connect the
probe tip to TRACKING GEN OUT. Adjust the probe for
optimum signal flatness on the CRT display.

3-11. Use the feedthrough terminations, 50 ohm and
600 ohm, when the device to be tested must be
terminated in its characteristic impedance (for example,
when measuring dBm). To make a feedthrough
termination for some other impedance, simply connect a
resistor across the analyzer INPUT (connect the resistor
to INPUT ground, not chassis ground). The value of the
resistor should be equal to the characteristic impedance
of the device.

CAUTION

Do not apply more than 10 V rms and
±200 Vdc to INPUT.

3-12. Amplitude Ranges

3-13. The LOG/LINEAR switch on the IF Section works
in conjunction with the dBm/dBV switch on the LF
Section. With LINEAR selected, the analyzer measures
voltage. With LOG selected (either 2 dB or 10 dB on the
8552B), the analyzer measures voltage in dBV (that is,
dB referenced to 1 volt) or power in dBm. The LF
Section is calibrated to measure dBm in 50 or 600 ohms.

3-14. To use 2 dB LOG, first find the signal using 10 dB
LOG; display the desired portion of the signal on the top
16 dB of the CRT display, then switch to 2 dB LOG. The
top of the display, the LOG REF graticule, remains the
same. The -70 dB graticule line becomes -14 dB (each
major division becomes 2 dB).

NOTE
Do not make any VERTICAL GAIN or
POSITION adjustments in 2 dB LOG
as the front panel calibration will
become invalid.

3-15. The LOG REF LEVEL control on the IF Section
has three scales (see EQUIPMENT SUPPLIED in
Section I): the red scale is used for LF Section log
calibration, the black scale is used for RF Section log
calibration, and the blue scale is used for linear
calibration on all units. If the IF Section being used does
not have the red scale, subtract 20 dB from the black
scale to obtain the LOG REF level on the CRT.

3-16. First Mixer Balance

3-17. The first mixer in the 8556A is balanced to insure
a low level of first local oscillator feedthrough appearing
on the display. Excessive LO feedthrough may result in
inaccurate amplitude calibration and excessive
intermodulation distortion. With the dBm/dBV switch set
to 50Ω dBm and INPUT LEVEL set to -60 dBm/dBV, the
first LO feedthrough (zero frequency marker) should be
below -80 dBm. If it is above this level, perform the first
mixer balance adjustment specified below.

3-1

Operation Model 8556A

3-18. Remove the top cover from the Display Section
(with power off).

WARNING
Removing the top cover from the
Display Section exposes the operator
to dangerous potentials (up to 7000
volts).

3-19. Set the analyzer controls as follows:

FREQUENCY......................................................0 kHz

BANDWIDTH.......................................................3 kHz

SCAN WIDTH ....................................... PER DIVISION

PER DIVISION.................................................. 10 kHz

INPUT LEVEL ..........................................-60 dBm/dBV

dBm/dBV ....................................................50 Q2 dBm

BASE LINE CLIPPER ............................................ ccw

VIDEO FILTER .................................................. 10 kHz

SCAN TIME PER DIVISION .............5 MILLISECONDS

LOG/LINEAR ..............................................10 dB LOG

LOG REF LEVEL ............................................ -40 dBm

SCAN MODE ..........................................................INT

SCAN TRIGGER ................................................AUTO

POWER ................................................................. ON

NOTE

This procedure assumes that the
analyzer is calibrated as specified in
Figure 3-2 and has been allowed to
warm up at least one-half hour.

3-20. Center the LO feedthrough signal on the display
with the FREQUENCY control.

3-21. Using a non-metallic adjustment tool, alternately
adjust C and R MIXER BALANCE ADJUSTMENTS
(available on the LF Section top cover) to null the LO
feedthrough.

3-22. When the signal is below -80 dBm, turn power off
and replace the top cover.

3-23. OPERATING INSTRUCTIONS

3-24. The following instructions should enable an
operator to make fast, accurate measurements with the
low frequency analyzer. To define each instrument
application is beyond the scope of this manual. For
further details, there is a complete discussion of 8556A
applications in Application Note 134. This application
note is available from your local HP Sales and Service
Office.

3-25. In general, operation of the Spectrum Analyzer
may be accomplished through the following steps:

a. Set the analyzer to scan the appropriate

frequency range with the proper resolution.

b. Adjust the amplitude scale as necessary for the

measurement.

c. Complete the measurement, and interpret the

results.

3-26. Setting the Frequency Scan

3-27. There are three ways to set the frequency scan on
the 8556A. The first is the 0-10f mode of operation.
When this mode is selected, the spectrum analyzer
scans from "zero" frequency to a preset upper limit
selected by the PER DIVISION control. For example, if
the PER DIVISION control is set to 10 kHz, and the 0­10f mode is selected, the spectrum analyzer will scan
from 0 to 100 kHz, 10 kHz per division. Scans may be
selected from 20 Hz per division to 20 kHz per division in
a 1, 2, 5 sequence.

3-28. The second way to set the frequency scan is the
PER DIVISION mode. In this mode, the frequency scan
is symmetrical about the CENTER FREQUENCY tuned
by the FREQUENCY control. The CENTER
FREQUENCY dial indicates this frequency in two
ranges, 0-30 kHz or 0-300 kHz. The horizontal scale is
then selected by the PER DIVISION setting.

3-29. The third way is the ZERO scan mode. The
spectrum analyzer becomes a fixed-tuned receiver at the
frequency indicated by the CENTER FREQUENCY dial.
In this mode, amplitude variations are displayed versus
time on the CRT.

3-30. Once the proper frequency scan is chosen, the
resolution needed for the particular measurement should
be determined. Resolution is mainly a function of the IF
bandwidth selected. As narrower IF bandwidths are
used, the resolution increases. At the same time, the
spectrum analyzer must be swept at a slower rate. The
bandwidth used should be only as narrow as is
necessary for the particular application. The best
procedure is to select the bandwidth necessary for the
desired resolution, and then slow the scan rate (SCAN
TIME PER DIVISION) until the DISPLAY UNCAL light is
unlit.

3-31. Adjusting the Amplitude Scale 3-32. Once the
desired signals are displayed on the CRT the amplitude
is set to give an optimum display. The first consideration
is how the amplitude is to be measured. The 8556A can
measure power in dBm (for 50 ohm or 600 ohm
systems), and it can measure voltage on a linear scale
or in dB referred to one volt (dBV) on a log scale.

3-33. If power is the desired parameter, set the
dBm/dBV switch to dBm for the appropriate

3-2

Model 8556A Operation

FRONT PANEL FEATURES

(1) DISPLAY UNCAL: warning light indicates that the

CRT display has become uncalibrated due to
incompatible settings of SCAN WIDTH, SCAN
TIME PER DIVISION, BANDWIDTH, and VIDEO
FILTER controls.

(2) FREQUENCY: tunes the CENTER FREQUENCY

in SCAN WIDTH PER DIVISION and ZERO scan
modes. FINE TUNE allows high resolution
adjustments in narrow scans.

(3) ZERO ADJ: calibrates CENTER FREQUENCY

dial for "zero" frequency.

(4) 300 kHz ADJ: calibrates CENTER FREQUENCY

dial for 300 kHz.

(5) BANDWIDTH: selects resolution bandwidth of the

spectrum analyzer from 10 Hz to 10 kHz in a 1, 3
sequence. (8552A, 50 Hz and 100 Hz to 300 kHz
in a 1, 3 sequence.)

(6) AMPL CAL: calibrates display amplitude for

absolute voltage and power measurements.

(7) CENTER FREQUENCY: dial indicates the

CENTER FREQUENCY for SCAN WIDTH PER
DIVISION and ZERO scan modes. Calibrated in 5
kHz increments for 0-300 kHz range and 500 Hz
increments for 0-30 kHz range.

(8) SCAN WIDTH: selects spectrum analyzer

frequency scanning mode. 0-10f repetitively tunes
the spectrum analyzer from "zero" frequency to ten
times the setting of the PER DIVISION control.
(e.g., with PER DIVISION control set at 1 kHz,
scan would be from 0-10 kHz, or 1 kHz per
division.) PER DIVISION mode scans the
spectrum analyzer symmetrically about the
CENTER FREQUENCY with a scan width set by
the PER DIVISION control. In the ZERO scan
mode, the analyzer becomes a fixed frequency
receiver at the CENTER FREQUENCY.

(9) PER DIVISION: selects the CRT horizontal

calibration (frequency scale) in the PER DIVISION
and 0-10f frequency scan modes.

(10) TRACKING ADJ: tunes the TRACKING GEN

OUT frequency to precisely track the tuning
frequency of the spectrum analyzer.

(11) INPUT LEVEL: adjusts the input signal level to

the input mixer and input preamplifier to maximize

dynamic range. This control should be set to
agree with the signal level read on the CRT.

(12) TRACKING GEN LEVEL: adjusts the output level

of the tracking signal present at the TRACKING
GEN OUT. When the CAL position is selected, it
gives an output of 100 mV for calibrating the
spectrum analyzer display. The output can be
increased to 3V.

(13) RANGE kHz : selects CENTER FREQUENCY dial

range of 0-30 kHz or 0-300 kHz.

(14) INPUT: one megohm unbalanced input for signals

to be measured.

(15) dBm/dBV: selects log display absolute calibration

for dB1V or dBm referred to 50 ohms or 600
ohms. For correct dBm measurements, an
external termination of the proper impedance must
be provided for the input signals.

(16) TRACKING GEN OUT: output signal tracks the

spectrum analyzer tuning frequency. The signal
may be used for swept frequency response
measurements or to drive a frequency counter for
accurate frequency measurements. The signal
output also serves to accurately calibrate the
display for absolute amplitude.

(17) kHz MARKERS: places crystal controlled

markers with 20 kHz spacing on CRT. These
markers are accurate to 0.01',, and are useful for
calibrating the frequency axis.

(18) CAL OUTPUT: -30 dBm, 30 MHz signal used for

calibrating amplitude on other tuning sections
(8553B,8554L.8555A).

(19) PEN LIFT OUTPUT, TRIG/BLANK INPUT:

provides -14 V pen lift signal for use with X-Y
recorders during retrace in SINGLE and INT
SCAN MODES with VIDEO. LINE, or AUTO
SCAN TRIGGER. It serves as an input connector
for external blanking signal in the EXT SCAN
MODE. When EXT SCAN TRIGGER is selected,
it becomes an input connector for the external
trigger signal.

(20) VERTICAL OUTPUT: provides output

proportional to vertical deflection on CRT.
Approximately 100 mV per major division with 100
ohm output impedance.

Figure 3-1. Front Panel Features (1 of 4)

3-3

(See foldout, page 3-5, for illustration)

Operation Model 8556A

FRONT PANEL FEATURES

(21) SCAN IN/OUT: provides output voltage

proportional to CRT horizontal deflection. 0 volts
equals center screen with 1 volt per division (-5 to
+5V full screen). Output voltage available in
SINGLE, MAN, and INT SCAN MODES. In EXT
SCAN MODE, the connector is used as an input
for 0 to +8V external scan signal.

(22) DISPLAY ADJUST: these controls adjust the

deflection circuit gain and offset levels to match
the IF section to a particular display section.

(23) LOG REF LEVEL LINEAR SENSITIVITY: these

controls set the absolute amplitude calibration of
the CRT display. In the 10 dB LOG or 2 dB LOG
modes, the sum of the two control settings
determines the LOG REF LEVEL (top graticule
line on CRT). In the LINEAR mode, the product of
the two control settings determines the CRT scale
factor in volts per division. A special knob is
provided for use with the 8556A. This knob is
described under OPERATING
CONSIDERATIONS (paragraph 3-15).

(24) LOG/LINEAR: selects display mode for

logarithmic display with scale factors of 10 dB per
division or 2 dB per division or LINEAR display
with scale factor selected by LINEAR
SENSITIVITY (2 dB per division not available with
8552A).

(25) SCAN TRIGGER: selects synchronizing trigger

when in the INT SCAN MODE.

AUTO: scan free runs.

SINGLE: single scan initiated by front panel

pushbutton. SCANNING lamp indicates time
during which analyzer is being scanned.

(27) Initiates or resets scan when SINGLE SCAN

MODE is selected.

(28) SCAN TIME PER DIVISION: selects time

required to scan one major division on CRT
display. Control acts as time base for time domain
operation in ZERO scan.

(29) VIDEO FILTER: post detection low pass filter for

effective averaging of distributed signals such as
noise.

(30) Bandwidths of 10 kHz, 100 Hz, and 10 Hz

selectable; nominal bandwidth 400 kHz in OFF
position. (10 Hz position not available with
8552A.) BASE LINE CLIPPER: allows blanking of
the bright base line area of the CRT for better
photography and improved display of transient
phenomena.

(31) MANUAL SCAN: controls spectrum analyzer

horizontal scan in the MAN SCAN MODE. (Not
available on 8552A.)

(32) CAL 10V and 1V: 10V or 1V square wave used

to calibrate time domain plug-ins ONLY.

LINE: scan synchronized to power line frequency.
EXT.: scan initiated by external positive or

negative pulses (2-20V) applied to TRIG/BLANK
INPUT.

VIDEO: scan internal synchronized to envelope of
RF input signal. Signal amplitude of 1.5 divisions
peak-to-peak (min.) required on display section
CRT.

(26) SCAN MODE: selects scan source.

INT.: analyzer repetitively scanned by internally

generated ramp; synchronization selected by
SCAN TRIGGER. SCANNING lamp indicates
time during which analyzer is being scanned.

EXT.: scan determined by externally applied 0 to
+8V signal at SCAN IN/OUT.

MAN: scan determined by MANUAL SCAN
control; scan continuously variable across CRT in
either direction. (Not available with 8552A.)

Figure 3-1. Front Panel Features (2 of 4)

3-4

(33) FOCUS: focuses CRT spot for best definition.
(34) BEAM FINDER: returns CRT trace to the center

of the screen regardless of deflection potentials
with time domain plug-ins ONLY.

(35) NON STORAGE, CONV: defeats the storage and

variable persistence features of the CRT.
Persistence is that of the standard P31 phosphor.

(36) INTENSITY: adjusts the intensity of the trace on

the CRT.

CAUTION
Excessive INTENSITY will damage
the CRT storage mesh. Whenever
trace blooming occurs, turn
INTENSITY down.

(37) ERASE: erases the CRT in the WRITING SPEED

FAST or STD mode of operation. CRT ready to
record immediately after erasure.