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I N ST RU CTIO N
U




7 L 12
SPECTRUM
A N A L Y Z ER

Serial Number - '



Te ktronix, Inc. t . . Box 500 Ao- Beaverton, Orego n 97005 + Ph one: 644-0161 t Cab les: Te k tronix

070-1298-01 772
WARRANTY


All TEKTRONIX instruments are warranted against
defective materials an d workmanship for one year . Any
q uestions with resp ect to the warranty should be taken up
with your TEKTRO N IX Field Engineer or representative .

All requests for repairs an d replacement p arts should be
directe d to the TEKTRONIX Fiel d Office or representative
in your area . This will assure you the fastest possible
service . P lease inclu d e the instrument Type N umber or P art
N umber and Serial Number with all re q uests for parts or
service .

Specifications an d price change privileges reserv



Copyright @ 1972, new material 1973, by Tektronix,
Inc., Beaverton, Oregon . Printed in the United States of
America. All rights reser v ed. Contents of this publication
may not b e repro d uce d in any form without permission of
Te k tronix, Inca


U .S.A. and foreign T EK T R O N IX pro d ucts covered by U .S .
a nd foreign p ate n ts an d /or p atents p ending .


TEKTRONIX is registered trademark of Tektronix, In
TA BLE O F CO N T EN TS

S ECTIO N 1 Specifications Page

Introduction
Electrical Characteristics 1-1

S ECTIO N 2 Operating I nst ru ctio ns

Introduction 2-1
Function of th e Fr ont P anel Controls and Connectors 2-1
Ge n eral Operating Info rmation 2-6
Preliminary Fro nt P anel Setu p and Calibration 2-6
P roced ure to M atch t h e 71_12 to the Oscillosco pe
2-6 Cali brati ng the Swee p
2-8Chec k and Adju st Log-Am p Cali bration
Chec k Lin Mode and 10 d B/Div Operation 2-9
2-9 er Operatio n
Adj ust Contrast an d C h ec k Baseline Clipp
U si ng the Analyzer
Signal Ap plication 2-9
R esolution, Se nsitivity and Fr equency Span
2-11
Gain Desensitizatio n Nea r 0 Hz 2-11
Selecting Sweep R ate 2-11
Trigge ring the Display 2-12
How to Sweep the Display U sing an External Swee p Source 2-13
External Trigge red Op eration U sing V ertical Am plifier
Plug-in U nit as the Source 2-14
U sing the Cal Out Signal R eference fo r Accurate F requ ency
and Ap plications 2-15
Applications 2-15

SECTIO N 3 P erfo rmance Chec k

Preliminary P reparation 3-1
Check 10 dB /DIV a nd L I N Mode Cali brations 3-1
Check the Freq uency R eadout Accuracy 3-1
Check Gain Selector Accuracy a nd V aria ble R ange 3-2
Check Operation of the V ideo F ilter
3-2
Check Se nsitivity 3-2
Check For Spur ious Signals (Resid ual R esponse) 3-4
Check Resol ution B andwid th s and Shape Factor 3-5
Check I nci dental FM 3-6
Perfo rmance Check s R equ iring Test Equipme nt
3-7E qu ipment R equired
Chec k Cali brator Fre q uency 3-8
Chec k Cali brator Outpu t 3-8
Chec k RF Atte nuato Accuracy 3-9
Chec k Display Flatness 3-9
Chec k Intermod ulation Distortion
3-10
Chec k Video Processor Operatio n
3-10
Chec k Time/Div Accuracy and Varia ble R ange 3-11
Chec k Trigge ring Operation and Se nsitivity 3-12
Check the H orizontal I nput V oltage R eq uirement 3-13
Check Freq Span Accuracy a nd L inea rity 3-13
TABLE OF CONTENTS (cont)

SECTION 4 Calibration Procedure Page
Equipment Required 4-1
Time Base Section
Adjust Sweep Triggering 4-2
Check and Adjust Timing 4-4
Function IF Alignment
Adjust LIN Mode Baseline Offset 4-5
Adjust Gain Compensation and Reference Level 4-5
Phase Lock Circuit
Phase Lock Adjustments 4-6
2nd LO and Shaper Calibration
Adjust 2nd LO Sweep Shaper Range and Center Frequency 4-8
Adjust Sweep Shaper 4-9
Voltage Memory Circuit
Adjust Voltage Memory (Cal and Offset) 4-9
Calibrate the 2nd Mixer and 2.095 GHz Filter 4-10
Freq Span and Marker Calibration
Adjust the 1st LO Power Supply Voltage and the Freq Span
of the Oscillator 4-11
Calibrate MAX SPAN Marker 4-12
50 MHz Calibrator
Adjust the Calibrator Output 4-13
Resolution
Adjust Bandpass of the 105 MHz 1 F Amplifier and 300 kHz
Filter 4-13
Adjust the Resolution Gain Leveling Compensation 4-16
Preliminary Adjustment of the Gain Slope For the
Resolution Amplifier 4-17
Adjust the Post Resolution Amplifier Gain 4-17
Minimize Intermodulation Products 4-18




SECTION 5 Circuit Description

Block Diagram Description 5-1
Detailed Circuit Description
Microwave Input Circuits 5-3
105 MHz IF Amplifier, 3rd Mixer and Oscillator 5-3
10 MHz IF Amplifier and Resolution Filter Circuits 5-4
Sweep Triggering 5-5
Sweep Generators and Holdoff 5-5
Sweep Span 5-5
YIG Coil Driver and Marker Generator 5-5
Voltage Memory and Phase Lock Operation 5-6
YIG Oscillator Power Supply 5-6
Sweep Shaper 5-6
Function IF Amplifier 5-7
Video Filter, Processor, Baseline Clipper and Vertical
Output 5-8
50 MHz Calibrator 5-9
TABLE OF CONTENTS (cont)

SECTION 6 Maintenance Information Page
Preventive Maintenance
Cleaning 6-1
Lubrication 6-1
Transistor and IC Checks 6-1
Performance Checks and Recalibration Troubleshooting 6-1
Troubleshooting Aids 6-2
Corrective Maintenance
Obtaining Replacement Parts 6-7
Soldering Technique 6-7
Replacing Square Pin for the Multi-pin Connectors 6-7
Replacing Assemblies and Sub-assemblies Maintenance Tools 6-7
Front Panel Potentiometers 6-8
Removing and Installing Freq Span/Resolution Knobs 6-8
Replacing or Repairing the Cam Switches 6-8
Replacing the Major Circuit Board Assemblies 6-9
Replacing the 2nd LO Varactor Assembly 6-10
Replacing the 2.095 GHz Filter Assembly 6-11
Replacing the 1st (YIG) Oscillator Assembly 6-11
Replacing the 2nd Mixer Assembly (Includes Calibration
Procedure after Replacement) 6-12
Replacing the Phase Detector and 2nd NO Hybrid Assembly 6-14
Replacing the Differential Attenuator Assembly 6-14


SECTION 7 Electrical Parts List 7-1


SECTION 8 Diagrams and Circuit Board Illustrations 8-1


SECTION 9 Mechanical Parts List and Illustrations (Exploded View) 9-1
Fig. 1-1 . 71-12 Spectrum Analyzer
Section 1-7L 12


S PE CI F ICATIO N S

Introduction Sectio n 9, Mechanical P arts List, E xp loded d rawi ngs an d
T his manual contai ns information re q uired to operate, Accessories : Pr ovides informatio n necessary to or der re-
test, cali brate, an d service the 71_12 Spectrum Analyzer . p laceable parts . Part L ist is cross-reference d to th e Electrical
T he manual is d ivi d ed into ten ma jor sections ; Parts List. E xplod e d drawi ng sh ows se qu ence of assem bly
an d i d entified assem blies .


Section 1, General Information an d Specifications .
Sectio n 10, Manual Changes and Corrections : P rovi des
h istory and upd ating informatio n for th e ma n ual in the
form of inserts . As th e ma nual is upd ated th ese inse rts are
Section 2, Operation Instructions : Information relative incorporated into th e manu al text and d iagrams.
to installing an d o perating the instru ment.



Section 3, Performance C hec k: P rovi des com plete
p roce du re to chec k operatio nal performance for an in- Description
co m ing acce p tance chec k, o r any add itional performance
chec ks that require test equi p ment to verify instrument The 7 L12 Spectrum Analyzer is d ual-wi dth plug-in
specificatio ns. u nit, for the 7000-Series Oscilloscopes . Wh en use d with any
of th ese oscilloscopes, it d is plays s p ectrum of signal
energy wit h in any freque ncy span to 1 .8 G Hz. The unit
co ntains h orizo ntal sweep an d timing circuits, for fre-
Section 4, Calibration P roce dure : Descri bes test equi p- quency an d time d omain d isplays, an d also means b y wh ich
ment setu p an d ad justment p roce d ures req uired to align the an extern al swee p source can be a p p lied to slave t h e 71_12
instru ments internal a d ju stme nts . to external devices, such as r ecord er .



Section 5, Circuit Description : P rovi d es b asic an d
general circuit analysis that may be useful when servicing or
operating t he instr u ment. SPE CI F ICATIO N S
ELECT R ICAL C HARACT ER ISTICS

Section 6, Mainte nance In structions : Descri bes routine
The following characteristics an d features of the 71_12
an d corrective maintenance proce d ures with d etaile d in-
Spectrum Analyzer are applicable after warm up pe rio d of
structions for replacing assemblies, su b-assem blies, an d
30 minutes or more .
in d ivi d ual com p onents . An ex ploded d rawing is p art of
section 9. Trou ble-sh ooting proced ures plus general infor-
Center F requency Operating R ange an d Accuracy
mation that may ai d in servicing the instru ments are also
p rovide d . From 0.1 MH z to 1 .8 G Hz. R ea dout accuracy is with in