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4961496P
SPECTRUM ANALYZER
WITH OPTIONS
7ielctronix COMMITTED TO EXCELLENCE




WARNING
THE FOLLOWING SERVICING INSTRUCTIONS
ARE FOR USE BYQUALIFIEDPERSONNELONLY .
TO AVOID PERSONAL INJURY, DO NOT
PERFORM ANY SERVICING OTHER THAN THAT
CONTAINED IN OPERATING INSTRUCTIONS
UNLESS YOU ARE QUALIFIED TO DO SO .




PLEASE CHECK FOR CHANGE INFORMATION
AT THE REAR OF THIS MANUAL.




49s149sP
SPECTRUM ANALYZER
WITH OPTIONS

SERVICE VOLUME 1




INSTRUCTIQN MANUAL
Tektronix, tnc.
P.O . Box 500
Beaverton, Oregon 97077 Serial Number
070-3481-00 First Printing APRIL 1981
Prgduct Group 26 Revised DEC 1982
4961496P Service Val. 1




TABLE ~F CONTENTS
This manual is divided into two volumes as follows:



vo~uME i



LIST OF ILLUSTRATIONS . . . . . . . . . . . . . . . . . . . . vii Section 3 CALIBRATION
LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . ix Introduction . . . . . . . . . . . . . . . . . . . . . 3-1
SERVICING SAFETY SUMMARY . . . . . . . . . . . . . . . x History Information . . . . . . . . . . . . . . . 3-1
Equipment Required . . . . . . . . . . . . . . 3-1
Section 1 GENERAL INFORMATION AND SPECI- PERFORMANCE CHECK PROCEDURE
FICATION , . . . . . . . . . . . . . . . . . . . . . . . 1-1 Introduction . . . . . . . . . . . . . . . . . . . . . 3-4
General Information . . . . . . . . . . . . . . . . . 1-1 Incoming inspection Test . . . . . . . . . . 3-4
Introduction . . . . . . . . . . . . . . . . . . . . . 1-1 Preliminary Preparation . . . . . . . . . . . 3-4
Product Service . . . . . . . . . . . . . . . . . i-1 1 . Check Operation of Front Panel
Instrument Construction . . . . . , , . . . . 1-1 Push Buttons and Controls . . 3-4
Elapsed Time Meter . . . . . . . . . . . . . . 1-2 2. Check Frequency Readout
Changing Power Input Range . . . . . . 1-2 Accuracy . . . . . . . . . . . . . . . . . 3-6
Replacing Fuses . . . . . . . . . . . . . . . . . 1-2 3. 496P TUNE Accuracy Check . 3-7
Selected Components . . . . . . . . . . . . 1-3 4. Check Calibrator . . . . . . . . . . . 3-8
Gomponent Circuit Numbering 5. Check RF Attenuator . . . . . . . 3-10
Scheme . . . . . . . . . . . . . . . . . . . . . . . . 1-3 6. Check IF Gain Accuracy . . . . . 3-11
Firmware Version and Error Message 7. Check Display Accuracy . . . . . 3-13
Readout . . . . . . . . . . . . . . . . . . . . . . . 1-3 8. Check Input 1 dB Compression
RackmountlBenchtop Versions . . . . . 1-3 Level . . . . . . . . . . . . . . . . . . . . 3-13
Specification . . . . . . . . . . . . . . . . . . . . . . 1-3 9. Check Gain Variations between
Electrical Characteristics . . . . . . . . . . 1-4 Resolution Bandwidths . . . . . . 3-14
Frequency Related . . . . . . . . . . . . . 1-4 10 . Check Frequency Response . . 3-15
Amplitude Related . . . . . . . . . . . . . 1-5 11 . Check Frequency SpanIDiv
~nput Signal Characteristics . . . . . . 1-7 Accuracy . . . . . . . . . . . . . . . . . 3-16
Output Signal Characteristics . . . . 1-8 12 . Check TimelDiv Accuracy . . . . 3-18
General Characteristics . . . . . . . . . 1-9 13 . Check Delta Frequency
Power Requirements . . . . . . . . . . . 1-9 Readout Accuracy . . . . . . . . . 3-20
Environmental Characteristics . . . . . . 1-10 14, Check Pulse Stretcher . . . . . . 3-20
Physical Characteristics . . . . . . . . . . . 1-11 15 . Check Resolution Bandwidth
ACCESSORIES . . . . . . . . . . . . . . . . . . . . 1-12 and Shape Factor . . . . . . . . . . 3-20
OPTIONS . . , . . . . . . . . . . . . . . . . . . . . . 1-12 16 . Check Equivalent Input Noise
Option 30 . . . . . . . . . . . . . . . . . . . . . . 1-12 Sensitivity . . . . . . . . . . . . . . . . 3-21
Option 31 , . . . . . , . , , , , , , , , , , , . . . 1-12 17 . Check Frequency Drift . . . . . . 3-21
Option 32 , . . . . . . . . , . . . . . . . . . . . . 1-12 18 . Check Residual FM . . . . . . . . 3-22
Options for Power Cord Configuration 1-13 19 . Check Intermodulation
Distortion . . . . . . . , , , . . . . . . 3-23
Section 2 INSTALLATION AND REPACKAGING 20, Check Harmonic Distortion . . . 3-23
Introduction . . , . . . . . . . . . . . . . . . . . . 2-1 21 . Check Phaselock Noise
Unpacking and Initial Inspection . . . . 2-1 Sidebands . . . . . . . . . . . . . . . . 3-24
Preparation for Use . . . . . . . . . . . . . . 2-1 22 . Check Spurious . Response . .
Power Source and Power Residual . . 3-26
Requirements . . . . . . . . . . . . . . . . . . . 2-1 23 . Check Zero Frequency
Repackaging for Shipment . . . . . . .. . . 2-2 Feedthrough Amplitude . . . . . . 3-26



REV ASR t sae
496/496P Service Vol. 1

TABLE OF CONTENTS (cont)

Section 3 CALIBRATION (cont) Page Section 4 MAINTENANCE (cont) Page
24. Check Digital Storage . . . . . . . 3-26
25. Check Triggering. Operation~ . . . 3-27
Transistor and Integrated Circuit
Checks . . . . . . . . . . . . . . . . . . . . . . . . 4-3 '

and Sensitivity Output. .. .. .. . . . . 3-28
Vertical .Signal Output 3-29
26. Check Horizontal
.. Performance Checks and Recalibration
TROUBLESHOOTING . . . . . . . . . ~ ~ ~ ~ ~ .
4-3
4-3

27. Check LO Emission Out of the
28. Check . . . . . . . . .~~~~~~ . 3-29
Troubleshooting Aids . . . . . . . . . . ~ . ~
General Troubleshooting Technique . .
4-3
4-5

RFINPUT Verification CORRECTIVE MAINTENANCE . . . . . . . 4-7

29. 496P GPIB. . . . . . .~~~~~~~~~~ 3-29
Program
Obtaining Replacement Parts . . . . . . .
Parts Repair and Return Programs . .
4-7
4-7
4-7

ADJUSTMENT PROCEDURELow Voltage
Soldering Techniques . . . . . . . . . . . ~ .


1. Check and Adjust. . . . . . . . . ~ ~ . 3-38
Replacing the Square Pin for the


Power Supply . Board) . . . 3-39
Multi-pin connectors . . . . . . . . . ~ ~ ~ ~ . 4-7


(Z-Axis
4-8

2. Crt DisplayAmplifier (Gain and
Selected Components . . . . . . . . . . ~ ~ .


3. Deflection Response) . . . . . . . 3-42
Installing Matched Crystals for the
4-8 .


4. Frequency1 st LO System. . and. . 3-44
100 Hz VR Filters . . . . . . . . . . ~ ~ ~ ~ ~ .

Adjust Sweep Timing . . .
Replacing EPROMS's or ROM's . . . . 4-8


5. CalibrateFrequency Control . . . 3-45
Firmware Version and Error Message
Readout . . . . . . . . . . . . . . . . . . . . . . . 4-8
Center
6. Check/Adjust. 2nd. . LO. . Tuning. . . 3-48
Servicing the VR Module . . . . . . . . . . 4-8


Range . . . . .Calibration. . .. . . . 3-52
. . . REPLACING ASSEMBLIES AND


7. Log Amplifier Resolution
SUBASSEMBLIES . . . . . . . . . ~ ~ ~ ~ ~ ~ . . 4-10


8. Calibrating the Shape Factor . 3-54
Removing and Replacing Semi-rigid '

and
Bandwidth the Variable
Coaxial Cables . . . . . . . . . ~ ~ ~ ~ ~ ~ ~ ~ ~ 4-10


9. Presetting Gain . . . . . . . . . . . 3-57
Replacing the Dual Diode Assembly . 4-10


Resolution
Replacing the Crt . . . . . . . . . ~ ~ ~ ~ ~ . . 4-10 ,


10.. Calibrator Output Level. . .. .. .. .. .. 3-58
Repairing the Crt Trace Rotation Coil 4-13


11 IF GainStorage Calibration . . . 3-58
Calibration . . Front Panel Assembly . . . . . . . . . . ~ . 4-13


12. Digital B-Save A Reference 3-60
Front Panel Board . . . . . . . ~ ~ ~ ~ ~ ~ ~ . 4-13


13. Setting. . . . . . . . . . . . . . : . . . . . 3-62
Replacing Front-Panel Push Button

Level Main Power Supply Module . . . . . . . .
High Voltage Power Supply . . . . . . . .
4-14
4-15

Section 4 MAINTENANCE. . . . . . . . . . ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ . 4-1
Introduction Components . . . . . . . 4-1
Replacing the 1 st (YIG) Oscillator
Interface Board . . . . . . . . . ~ ~ ~ ~ ~ ~ ~ . . 4-15

Static Sensitive
PREVENTIVE MAINTENANCE. .. .. .. .. .~ .~ .. .. 4-2
MAINTENANCE ADJUSTMENTS . . . . . 4-16


Elapsed Time. . Meter. .. .. .. .. .. . . . . . . . . . 4-2
110 MHz IF Assembly Return Loss
4-16

Cleaning . . . . .. .. .. .. . . .~~~~~~~~~~~~ 4-2
Calibration . . . . . . . . . . . . ~ ~ ~ ~ ~ ~ ~ ~ ~ .
4-16
4-2
2072 MHz 2nd Converter . . . . . . . . . .
Lubrication and Tools for
Service Fixtures. . . . . . .~~~~~~~~~~~~ 4-2
Four Cavity Filter . . . . . . . . . . . . . .
Mixer . . . . . . . . . . . . . . . . . . . . . . .
4-16
4-17

Maintenance .
Visual Inspection . . . . . . . . . ~ ~ ~ ~ ~ ~ ~ 4-3
110 MHz Three Cavity Filter . . . . .
Zero-Hertz Response Adjustment .
4-17
4-18




REV APR 1982
496149fiP Service Vol. 1




TABLE OF CONTENTS (cont)
Page Page
Section 4 MAINTENANCE (cont) Section 5 THEORY OF OPERATION (cont)


1 st LO Phaselock Calibration . . . . . . . 4-19 2nd Filter Select . . . . . . . . . . . . 5-24
2nd LO Calibration . . . . . . . . . . . . . . . 4-21 Post VR Amplifier . . . . . . . . . . . 5-26
Oscillator Section . . . . . . . . . . . . . . 4-21 Digital Control . . . . . . . . . . . . . . 5-26
Phaselock Section . . . . . . . . . . . . . 4-25 5 Valt Regulator . . . . . . . . . . . . 5-26
MICROCOMPUTER SYSTEM Logarithmic Amplifier and Detector 5-27
MAINTENANCE . . . . . . . . . . . . . . . . . . . 4-29 Lag Amplifier . . . . . . . . . . . . , . . 5-27
Memory Board Option Switch . . . . . . 4-29 Detector . . . . . . . , . . . . . . . . . . 5-28
Power-Up Self-Test Mode . . . . . . . . . 4-30 Display Section . . . . . . . . . . . . . . . . . . 5-30
Microcomputer Test Mode . . . . . . . . . 4-31 Video Amplifier . . . . . . . . . . . . . . . . 5-31
Instrument Bus Check Mode . . . . . . . 4-33 Log Mode . . . . . . . . . . . . . . . . . 5-31
TROUBLESHOOTING ON THE Linear Mode . . . . . . . . . . . . . . . 5-32
INSTRUMENT BUS . . . . . . . . . . . . . . . . 4-35 Pulse Stretcher . . . . . . . . . . . . . 5-33


I.
Instrument Bus Data Transfers . . . . . 4-35 Digital Control . . . . . . . . . . . . . . 5-33
Instrument Bus Registers . . . . . . . . . . 4-38 Video Pro~essor . . . . . . . . . . . . . . 5-33
49611405 TV Sideband Adapter



I.
Section s THEORY OF OPERATION System . . . . . . . . . . . . . . . . . . . 5-33
Functional and General Description . . 5-1 Video Marker . . . . . . . . . . . . . . 5-35
Detailed Description . . . . . . . . . . . . . . . . 5-3 Video Leveling . . . . . . . . . . . . . . 5-35



I.
1 st Converter Circuits . . . . . . . . . . . . 5-3 Video Filter . . . . . . . . . . . . . . . . 5-35
RF InterfacelZ Axis . . . . . . . . . . . . 5-4 Video Blanking . . . . . . . . . . . . . 5-35
1 st Converter . . . . . . . . . . . . . . . . . 5-4 Digital Storage . . . . . . . . . . . . . . . . 5-37
1 st LO Phaselock System . . . . . . . 5-5 Vertical Section . . . . . . . . . . . . . 5-38


I.
1 st LO Phaselock Control . . . . . 5-6 Horizontal Section . . . . . . . . . . . 5-42
1 st LO Error Amplifier and Deflection Amplifiers . . . . . . . . . . . 5-44
Synthesizer . . . . . . . . . . . . . . . . 5-9 Horizontal Section . . . . . . . . . . . . . 5-44



I.
1 st LO Controlled Oscillator, Vertical Section . . . . . . . . . . . . . . . 5-45
Offset Mixer, and Strobe Driver 5-11 Crt Readout . . . . . . . . . . . . . . . . . . . . 5-45
2nd Converter Circuits . . . . . . . . . . . . 5-13 Z Axis Circuits . . . . . . . . . . . . . . . . . . 5-53



I
2nd Converter . . . . . . . . . . . . . . . . 5-13 Z Axis Driver Amplifier . . . . . . . . . . 5-53
2nd LO Phaselock System . . . . . . 5-13 High Voltage Supply . . . . . . . . . . . 5-53
2182 MHz Microstrip Oscillator 5-15 Frequency Control Section . . . . . . . . . 5-54
2200 MHz Reference Board . . . 5-16 Sweep . . . . . . . . . . . . . . . . . _ . . . . 5-55


I-
2200 MHz Reference Mixer . . . 5-16 Span Attenuator . . . . . . . . . . . . . . 5-58
16-20 MHz Phaselock Board . 5-16 Center Frequency Control . . . . . . . 5-61
3rd Converter Circuits . . . . . . . . . . . . 5-18 1st LO Driver . . . . , . . . . . . . . . . . . 5-64



I-
110 MHz IF Amplifier . . . . . . . . . . . 5-18 Digital Control Section . . . . . , , . . . . . 5-67
110 MHz Bandpass Filter . . . . . . . 5-20 Processor . . . . . . . . . . . . . . . . . . . . 5-67
3rd Converter . . . . . . . . . . . . . . . . . 5-20 Memory . . . . . , . . . . . . . . : . . . . . . 5-77



I
IF Section . . . . . . . . . . . . . , . . . . . . . . 5-21 Front Panel . . . . . . . . . . . . . . . . . . 5-78
Variable Resolution Circuits . . . . . . 5-21 Accessories Interface Board . . . . . 5-83
Input . . . . . . . . . . . . . . . . . . . . . 5-21 Power Supply Section . . . . . . . . . . . . 5-84
1 st Filter Select . . . . . . . . . . . . . 5-22 Main Power Supply . . , , . . . . . . . . 5-84
10 dB Gain Steps . . . . . . . . . . . 5-23 Fan Drive . . . . . . . . . . . . . . . . . . . , 5-87
20 dB Gain Steps . . . . . . . . . . . 5-23 496P General Purpose Interface
Band Leveling . . . . . . . . . . . . . . 5-24 Bus . . . . . . . . . . . . . . . . . . . . . . . 5-88




REV APR 1982 Iii
4961496P Service Vol . 1




TABLE OF CONTENTS (cont) 0
Page SCHEMATIC DIAGRAMS
(divided by functional groups)
Section 6 RACKMOUNTIBENCHTOP VERSIONS
Introduction . . . . . . . . . . . . . . . . . . . . . 6-1 10 RF Interconnect
Electrical Characteristics . . . . . . . . . . 6-1 1 st CONVERTER CIRCUITS
Standard Accessories . . . . . . . . . . - - - . . 6-3
11 1 st Converter
Optional Accessories . . . . . . . . . . . . . . - - 6-3
12 1 st LO Phaselock Control
Rackmaunting Installation Dimensions . - 6-3
13 1 st LO Error Amplifier and Synthesizer
Slide-Out Tracks . . . . . . . . . . . . . . - . . . . 6-3 ~4 1 st LO Controlled Oscillator, Offset Mixer,
Mounting Procedure . . . . . . . . . . . . - - 6-4
and Strobe Driver
Alternate Rear Mounting Methods . . . 6-6
Slide-Out Track Lubrication . . . . . . . . 6-8 2nd CONVERTER CIR~UITS
Removing or Installing the 4961496P 15 2nd Converter
Spectrum Analyzer from or in 16 2nd LO (Oscillator Section)
the Rackmount Cabinet . - . . . . . . . . . 6-8
17 2nd LO (Phaselock Section)
Removing the Side, Top, and Bottom
Panels . . . . . . . . . . . . . . - - - - - - - - - ~ ~ 6-$ 3rd CONVERTER CIRCUITS
Installing Semi-rigid Coaxial Cables to 18 110 MHz iF Amplifier
Access the Cabinet Rear Panel 19 3rd Converter
Connectors to the Front Panel
of the Instrument {Option 31) . . . . . . . 6-8 IF SECTION
PREPARING THE INSTRUMENT FOR 20 No . 1 VR
CALIBRATION OR MAINTENANCE . . . . 6-10 21 No . 2 VR (Gain Steps)
22 No . 2 VR (Filter and Post Amplifier)
Appendix A GLOSSARY 23 Lag Amplifier and Detector

CHANGE INFORMATION DISPLAY SECTION

24 Video Amplifier
25 Video Processor and 1405 Interface
26 Digital Storage (Vertical}
27 Digital Storage (Horizontal)
VOLUME 2 28 Deflection Amplifier
29 Crt Readout
SERVICING SAFETY SUMMARY 30 Z AxisIRF Interface
31 High Voltage Supply
Section 7 REPLACEABLE ELECTRICAL PARTS

Section 8 DIAGRAMS FREQUENCY CONTROL SECTION

32 Sweep
BLOCK DIAGRAMS 33 Span Attenuator
1 Functional 34 Center Frequency Control
2 1 st Converter 35 1 st LO Driver
3 2nd Converter DIGITAL CONTROL SECTION
4 3rd Converter
5 IF Section 36 Processor
6 Display Section 37 Mempry
7 Frequency Control Section 38 Front Panel
8 Digital Control Section 39 GPIB and GPIB Interface
9 Power Supply Section 40 Accessories Interface



IV REV APFi 1982
49SI4g6P Service Vol. 1




TABLE OF CONTENTS (cont)

Section 8 DIAGRAMS (cant) Section 9 REPLACEABLE MECHANICAL PARTS
Digital Control
PpWER SUPPLY SECTION System Description
41 Main Power Supply (Primary Section) Processor
42 Main Power Supply (Secondary Section) Memory Board
43 Mother Board (Front) Front Panel
44 Mother Board (Rear) Accessories Interface Board

Main Power Supply and Fan Driver
Main Power Supply
Fan Driver Board
4981496P Service Vol. 1




LIST OF ILLUSTRATIONS
Fig. Fig.
No . Page lVo. Page

The 4961496P Spectrum Analyzer
1-1 Probe Power Connector . . . . . . . . . . . . . . . 1-10 3-23 Adjustments and test points on the deflec-
1-2 Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . 1-12 tion amplifier, High Voltage module, and Z
1-3 International power cord and plug configura- AxisIRF Interface board . . . . . . . . . . . . . . . 3-4D
Lion for the 496 . . . . . . . . . . . . . . . . . . . . . . 1-13 3-24 Location of wire strap (W4036} on high volt-
3-1 Test equipment setup for checking frequency age circuit board . . . . . . .~. . . . . . . . . . . . . . 3-40
_ of the calibrator and the accuracy of the fre- 3-25 Test equipment setup for calibrating , the. De-
quency readout . . 3-7 flection Amplifier . . 3-41
3-2 Test equipment setup showing two methods 3-26 Location of TP1011 on Crt readout . . . . . . 3-41
that check calibrator output level . . . . . . . . 3-9 3-27 Test points and adjustments on the Deflec-
3-3 Test equipment setup for.verifying. attenuator tion Amplifier board for gain and. frequency
and gain accuracy . . 3-11 response calibration . . 3-42
3-4 Test equipment setup for checking input 3-28 Test equipment setup for calibrating sweep
1 dB compression level . . . . . . . . . . . . . . . . 3-14 timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-43
3-5 Test equipment setup for checking the 0- 3-29 Location of timing adjustment R51 D5 and
10 MHz frequency response . . . . . . . . . . . . 3-16 TP1061 on the sweep board . . . . . . . . . . . . 3-44
_ 3-6 Test equipment setup for measuring the 3-30 Test equipment setup for calibrating sweep
0.01-1 .8 GHz frequency response . . . . . . . . 3-17 ramp for the 1 st LO Driver . . . . . . . . . . . . . 3-46
3-7 Typical display shwoing frequency response 3-31 1 st LO balance and span adjustments and
from a sweeping signal source . . . . . . . . . . 3-18 test points . . . . . . . . . . . . . . . . . . . . . . . . . . 3-47
3-$ Test equipment setup for checking span and 3-32 Test equipment setup for check and adjust-
timing accuracy . . . . . . . . . . . . . . . . . . . . . . 3-19 meet of 2nd LO Tuning Range . . . . . . . . . . 3-48
3-9 Display to illustrate how timing accuracy is 3-33 Center Frequency control adjustment loca-
checked . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-19 tions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-49
3-10 Measuring resolution bandwidth and shape 3-34 Equipment setup far calibrating Log Amplifier 3-52
factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-21 3-35 Location of connectors and adjustments on
3-11 Digital stored display showing drift . . . . . . . 3-22 the Log and Video Amplifier . . . . . . . . . . . . 3-53
3-12 Measuring residual {incidental} FM . . . . . . . 3-23 3-36 Test equipment setup for calibrating the VR
3-13 Test equipment setup for measuring section . . . . . . . . . . , , , . . . . . . . . . . . . . . . . 3-55
intermodulation distortion . . . . . . . . . . . . . . 3-24 3-38 Response of the 100 kHz filter . . . . . . . . . . 3-56
3-14 Intermodulation products . . . . . . . . . . . . . . 3-24 3-37 Calibration adjustments on the VR #2 mod-
3-15 Test equipment setup to check harmonic dis- ule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-55
tortion . , , . . . . . . . , . . . . . . . . . . , , . . . . . . 3-25 3-39 Calibration adjustments on the VR #1 mod-
3-16 Typical display of phaselock noise . . . . . . . 3-25 ule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-56
3-17 Multiple exposure to illustrate how the differ- 3-40 Typical response of the 10 kHz, 100 kHz,
ential between two signals can be measured 3-26 and 1 MHz bandwidth filters . . . . . . . . . . . . 3-57
3-i8 Test equipment setup for checking triggering 3-41 Test equipment setup for adjusting iF gain . 3-59
requirements . . . . . . . . . . . . . . . . . . . . . . . . 3-27 3-42 Digital Storage adjustment locations . . . . . 3-61
3-19 Test equipment setup to check external trig- 3-43 Location of binary switch (S7 D14) for setting
Bering and horizontal input characteristics . 3-28 B-SAVE A reference level . . . . . . . . . . . . . 3-62
3-20 Test oscilloscope display of a sinewave input 4-1 Multipin (harmonica) connector configuration 4-4
signal to EXT TRIG connector (input 0 .5 V 4-2 Color code for some tantalum capacitors . . 4-4
peak to 1 .0 V peak to peak . . . . . . . . . . . . 3-29 4-3 Diode polarity markings . . . . . . . . . . . . . . . 4-5
3-21 Display of a full screen signal at the Vertical 4-4 Pin configuration for semiconductor campo-
Ouptut Connector . . . . . . . . . . . . . . . . . . . . 3-29 vents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6
3-22 Low voltage power supply adjustments and 4-5 Preparing the VR module for service showing
test point locations . . . . . . . . . . . . . . . . . . . 3-39 how it is supported when on an . extender . 4-9


REV APR 1982 VII
496I496P Service Vol. 1




LIST OF ILLUSTRATIONS (cont)
Fig-
Fig. Page
No . Page No .

View of the 496I496P RF deck showing ma- 5-6 Log amplifier gain curve showing breakpoint 5-29
4-6
jor assemblies . . 4-11 5-7 Ends of fogging range . . . . . . . . . - - - - - ~ ~ - 5-29
View of the 496I496P .top .deck showing ma- 5-8 Simplified detector circuit . . . . . . . . . . . . - - 5-30
4-7
Selection of display position on log scale . . 5-32
jor asemblies . . . . - - - - . . . . . - - - ~ ~ ~ ~ ~ - - - 4-12 S-9
Removing YiG oscilator interface circuit 5-iD 49611405 TV Sideband Adapter System . . 5-34
4-8
board . . . . . - - - ~ ~ ~ ~ ~ ~ ~ - - - - - ~ ~ ~ ~ ~ - - - - - 4-15 5-11 Video filter simplified schematic . . . . . . . . . 5-36
5-12 Vertical control IC block diagram . . . . . . . . 5-39
4-9 Test equipment setup for adjusting return
Horizontal control IC block diagram . . . . . . 5-43
loss of the 110 MHz IF assembly . . . . . . . . 4-17 5-13
5-14 Simplified crt readout block diagram . . . . . 5-46
4-10 Location of the 110 MHz IF return loss ad-
justments and lF Gain adjustment . . . . . . . 4-17 5-15 Character onloff timing . . . . . . . - - - - - ~ ~ . . 5-47
Character scan . . . . . . . . . - - - - - ~ ~ ~ ~ ~ - - . 5-48
4-10A Adjustment locations for start spur amplitude 4-18 5-16
Test equipment setup for calibrating the 5-17 Character generator (01028) block diagram 5-49
4-11
Phaselock assembly . . . . . . . . . . . . - - - . . . 4-i9 5-18 Character scan timing . . . . . . . . . . . . . . . . - 5-50
Adjustments and test point ~ocations within 5-19 Dot delay circuit timing . . . . . . . . . . . - - ~ - ~ 5-51
4-12
Frquency dot marker circuit and timing . . . 5-52
the Phaselock assembly . . . . . . . . . . . - - - . 4-21 5-20
5-2i Sweep "interrupt' circuits . . . . . . . . . . . . - - 5-58
4-13 Test equipment setup for calibrating oscilla-
Simplified digital-to-analog converter . . . . . 5-6D
for section of the 2nd LO . . . . . . . . . . . . - . 4-23 5-22
Adjustments and test point locations within 5-23 Simplified span decade attenuatar . . . . . . . 5-61
4-14
the oscillat~r secti~n . . 4-24 5-24 DAC variance graph . . . . . . . . . . . . . - - - - - 5-62
Test equipment setup for calibrating the . . 5-25 Basic tune voltage converter . . . . . . . . . . . 5-63
4-15
phaselock section of the 2nd LO . . . . . . . . 4-27 5-26 Simple logic diagram of processor clock . . 5-68
Adjustments and test point locations on the 5-27 Block diagram of 6800 microprocesor . . . . 5-69
4-16
16-20 MHz phaselock board . . . . . . . - - - - ~ 4-28 5-28 Read and write cyc~e timing on the micro-
Location of the fine tune range pot (84040) computer bus . . . . . . . . . . - - - - - - - - - - - - - 5-71
4-17
on the center frequency control board and 5-29 Flaw chart of the 6800 main decision paths 5-72
the sweep gain pot {81067) on the span at- 5-30 6821 PIA registers and control lines . . . . . . 5-74
tenuator board . . . . . . - - - - ~ ~ ~ ~ - - - - - ~ ~ . - 4-24 5-31 A 6800 write to the instrument bus . . . . . . 5-76
The Memory board ~ption switch band 5-32 Instrument bus poll sequence . . . . . . . . . . . 5-77
4-i8
5-33 5witchmatrixcodes . . . . . . . . . . . . . . .-- . 5-79
51033 . . . . . .---~~~~-~~~~~~~~~~-~~~ . 4-31
A15 through A12 in microcomputer test 5-34 Scan by simplified keyboard encoder . . . . . 5-80
4-19
mode . . . . . . . . . - - - - ~ ~ ~ ~ - - - - ~ ~ ~ - ~ - - - - 4-33 5-35 The keyboard encounter . . . . . . . . . . . . . . . 5-Bi
A15 and YO through Y2 of address decoder 5-36 Frequency control encoder timing . . . . . . . . 5-82
4-20
5-37 Primary regu~ator input and output wave-
02044 . . . . . . . . . . - - - - ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ - - - 4-33
forms (stylized) . . . . . . . . . . - - - - - ~ ~ ~ ~ ~ - - 5-85
4-21 Enable and YO through Y2 of address decod-
. . . . . . . . - - - - - - - ~ - - 4-33 5-38 Timing waveforms (stylized) far soft-start cir-
er U1037B . .
board address decoder cult . . . . . . . . . . . . - - - - - - - - - - ~ ~ ~ ~ ~ ~ ~ ~ ~ . 5-86
4-22 A15 and Memory
. 4-34 5-39 9914 GPIA block diagram . . . . . . . . . . . - - - 5-89
outputs .
Y2 of address decoder 6-1 Hardward provided for slide track mounting 6-3
4-23 A15 and YO ,through
01028 on the GPIB board . . . . . . - - ~ - ~ ~ . 4-35 6-2 Instrument installed in a cabinet-type mount-
ing . . . . . . . . . - - . - . . w - - - - - . - . . . - . - . 6-4
4-24 One enable and outputs LORMA, HIRAM,
and GPS of address decoder 01028 on the 6-3 Complete slide-out track assemblies . . . . . 6-5
GPIB board . . . . . . . . . - - - - ~ ~ ~ ~ ~ ~ ~ - ~ ~ ~ - 4-35 6-4 Methods of mounting the stationary sections 6-5
Instrument bus check . . . . . . . . . . . . . - - - . 4-35 6-5 Measurements of front-rail mounting holes
4-25
Timing diagram for F ERROR signal . . - . . 5-8 for stationary sections . . . . . . . . - - - - ~ ~ ~ . . 6-6
5-1
Filter cross-section view . . . . . . - - - - ~ ~ . . . 5-14 6-6 Procedure for inserting or removing the in-
5-2
Filter equivalent circuit . . . . . . . . . . . . . - - - . 5-14 strument . . . . . . . . . . - - - - - - ~ ~ ~ ~ - - - - - ~ . 6-7
5-3
Bridged T attenuator equivalent schematic 5-19 6-7 Alignment adjustment for correct operation 6-8
5-4
Three-stage lag amplifier . . . . . . . . . . . . . - - 5-28 6-8 Alternative method of i~istalling the instru-
5-5
ment using rear support brackets . . . . . . . . 6-9
REV APR 1982
Yill
4961496P Semite Vol. 1




LIST OF TABLES
Table Table
No. Page No . Page


4-13 Sweep Registers . . . . . . . . . . . . . . - - - - - - . 4-43
1-1 Electrical Characteristics - . . . . . . . . . . . . . . 1-4
4-14 Span Attenuator Registers {75 and 76) . . . 4-44
1-2 Environmental Characteristics . . . . . . . . . . . 1-10
1-11 4-15 1 st LO Driver Register (72) . - . . . . . . . . . . . 4-44
1-3 Physical Characteristics . . . . . . . . . . . . . . .
2-1 Shipping Carton Test Strength . . . . . . . . . . 2-2 4-16 Center Frequency Control Registers (70, 71,
3-1 Equipment Required for Calibration . . . . . . 3-1 and FO) . . . . . . . . . . . . . . . . . .-- . . . . . . . . 4-45

3-2 Correction Factor to Determine True Signal 4-17 '1st LO Phaselock Control Registers (73 and
Level . . . . . . . . .- . . . . . . . . . . .-- . . . .-- . 3-12 F3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-45
5-1 RF Interface Lines . . . . . . . . . . . . . . . . . . . - 5-4
3-3 Recommended Test Equipment . . . - - . . . . 3-15
3-4 SpanIDiv vs Time Markers . . . . . . . . . . . . . 3-18 5-2 U2025 Output Lines . . . . . . . . . . . . - - - - - - 5-10
5-3 Bandwidth Selection . . . . . . . . . . . . . - . . . . 5-22
3-5 Adjustment Steps for Calibrating the
5-4 Gain Step Combinations . . . . . . . . . . . - - - . 5-24
496149fiP . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-37
3-38 5-5 Progression of Gain Reduction . . . . . . . . . . 5-25
3-6 Power Supply Voltage Tolerances . . . . . . .
3-7 Resolution and Sweep Rate as a Function of 5-6 Filter Component Combinations - . . . . . . . . 5-38
5-7 Control Port . . . . . . . . . . . . . . . . . . . . - - - - - 5-50
Span in the Auto Mode . . . . . . . . . . . . . . . . 3-45
5-8 AddresslData Port . . . . . . . . . . . - - - - - - - ~ 5-51
4-1 Relative Susceptibliity to Static Discharge
Damage . . . . . - . . . . . . . . . . . . . . . . . . . . - . 4-1 5-9 J2039 Truth Table . . . . . . . . . . . . . . . . . . . . 5-53
5-10 Sweep Rate Selection Codes . . . . . . . . . . . 5-57
4-2 Equipment Required for 110 MHz IF Assem-
bly Calibration . . - - . . . . . . . . . . . . . . . . . . . 4-16 5-11 Calibration Control Selection Codes . . . . . . 5-60
4-3 Equipment Required for 1 st LO Phaselock 5-12 Attenuation Selection Codes . . . . . . . . . . . - 5-60
4-19 5-13 ADDRESS 70 Formats . . . . . . . . . . - - - - - - 5-62
Calibration . . . . . . . . . . . . . . . . . . . . . . . . - -
5-14 DAC Tuning Codes . . . . . . . . . . . . . .- . . . . 5-64
4-4 Equipment Required far 2nd LO Calibration 4-22
4-5 Equipment Required for 2nd LO Phaselock 5-15 U4017 {U3027) Output Lines . . . . . . . . . . . 5-66
4-26 5-1 fi Condition Codes . . . . . . . . . . . . . . . . - - - - - 5-fib
Calibration . . . . . . . . . . . . . . . . . . . . . . - . . .
5-17 Address Select Lines . . . . . . . . - - - - - - - - ~ 5-70
4-6 Variable Resolution Data Register {3F) . . - - 4-40
4-7 Log & Video Amp Registers (78 and 79) . . 4-40 5-i8 496 Microcomputer Address Space . . . . . . 5-73
4-41 5-19 PIA Register and Interface Select Codes . . 5-73
4-8 Video Processor Control {7C} . . . . . . . . . . .
5-20 Instrument Bus Register Addresses . . . . . . 5-75
-- 4-9 Digital Storage Registers (7A, FA, and. 7B} 4-41
4-10 Z-Axis and RF Deck Control {4F) . . 4-42 5-21 Parallel POLL Byte . . . . . . . . . . . . . . . . . . - 5-76
4-42 5-22 GPIA Registers . . . , . . . . . . . . . . . . . - - - - - 5-90
4-11 Crt Readout Registers (5F and 2F) . . . . . . .
4-43 6-1 Environmental Characteristics . . . . . . . . . . . 6-2
_ _, 4-12 Front-Panel Registers . . . . . . . . . . . . . . . . .
6-2 Physical . . . . . . . . . . . . . . .-- . . . . . . . . . . . 6-2




REV APR 1982
4961496P Semite Vol. 1




SERVICING SAFETY SUMMARY

FOR QUALIFIED SERVICE PERSONNEL ONLY


Do Not Service Alone
SYMBOLS
Do not perform internal service or adjustment of this prod-
uct unless another person capable of rendering first aid and In This Manual
resuscitation is present .
This symbol indicates where applicable cau-
tionary or other information is to be found.
Use Care When Servicing With Power On
Dangerous voltages exist at several points in this product .
To avoid personal injury, do not touch exposed connections As Marked on Equipment
and components while power is on .
DANGER-High voltage.

Disconnect power before removing protective panels, sol-
dering, or replacing components .
O Protective ground (earth) terminal .


Power Source ATTENI"iON--refer to manual .

This product is intended to operate from a power source
that will not apply more than 250 volts rms between the
supply conductors or between either supply conductor and
Power Source
ground . A protective ground connection by way of the
grounding conductor in the power card is essential for safe This product is intended to operate from a power source
operation. that will not apply more than 250 volts rms between the
supply conductors or between either supply conductor and
ground . A protective ground connection by way of the
TERMS grounding conductor in the power cord is essential for safe
operation .

In This Manual
CAUTION statements identify conditions or practices that
Grounding the Product
could result in damage to the equipment or other property .
This product is grounded through the grounding conductor
of the power cord . To avoid electrical shock, plug the power
WARNING statements identify conditions or practices that cord into a properly wired receptacle before connecting to
could result in personal injury or loss of life . the product input or output terminals. A protective ground
connection by way of the grounding conductor in the power
cord is essential for safe operation .
As Marked on Equipment
CAUTION indicates a personal injury hazard not immediate-
ly accessible as one reads the marking, or a hazard to prop-
erty including the equipment itself . Danger Arising From Loss of Ground
Upon loss of the protective-ground connection, all accessi-
DANGER indicates a personal injury hazard immediately ac- ble conductive parts (including knobs and controls that may
cessEble as one reads the marking. appear to be insulating) can render an electric shock .
4961496P Service Vol . 1

Use the Proper Power Cord Use the Proper Fuse
Use only the power cord and connector specified for your To avoid fire hazard, use only the fuse specified in the parts
product. list for your product, and which is identical in type, voltage
rating, and current rating .

- Use only a power cord that is in good condition .
Refer fuse replacement to qualified service personnel.
. ..
For detailed information on power cards and connectors,
see the General Information and Specifications sections .
Do Not Operate in ~xplosi~e Atmospheres
To avoid explosion, do not operate this product in an atmo-
Fiefer cord and connector cF~anges to qualified service sphere of explosive gases unless it has been specifically
personnel. certified for such operation .
Service Vol 1 496/496P Spectrum Analyzer


496/496P .




The .
Section 1-4961496P Service Vol . 1




GENERAL INFORMATION
AND SPECIFICATION


GENERAL INFORMATION
Introduction from the Institute of Electrical and Electronic Engineers, 345
47th Street, New York, NY 1fl017 .
The Service manual consists of two volumes that contain
information necessary to test, adjust, and service the Porta-
ble RackmountlBenchtop 4961496P Spectrum Analyzer .
The intent is to provide as complete information as possible Product Service
as an aid in servicing this instrument . The Table of Oantents
To assure adequate product service and maintenance for
at the beginning of Volume 1 lists contents of each section
our instruments, Tektronix has established Field Offices and
contained within Volume 1 .
Service Centers at strategic points throughout the United
States and in countries where our products are sold . Sever-
al types of maintenance or repair agreements are available.
Change information that involves manual corrections
For example; for a fixed fee, a maintenance agreement pro-
andlor additions pending manual reprint and bind, is located
gram provides maintenance and re-calibration on a regular
at the back of the Service manual in the CHANGE INFOR-
basis. Tektronix will remind you when a product is due for
MATION section.
recalibration and perform the service within a specified time .
Contact your local Service Center, representative, or sales
engineer for details regarding : Warranty, Calibration, Emor-
1 History knformation with the updated data is integrated