Tektronix 7L13 User manual

070-1673-00
TEKTRONIX
7L13
SPECTRUM
ANALYZER
INSTRUCTION
MANUAL
Tektronix, Inc .
P .O . Box 500
Beaverton, Oregon 97005

Serial Number
First Printing APR 1974

WARRANTY
All TEKTRONIX instruments are
warranted
against
defective materials and workmanship for one year .
Any questions
with
respect to the warranty, should
betaken up with yourTEKTRONIX Field Engineeror
representative .
All requests for repairs and replacement parts
should be directed to the TEKTRONIX Field Office
or representative in your area . This will assure you
the fastest possible service . Please include the
instrument Type Number or Part Number and Serial
Number with
all
requests for parts or
service .
Specifications and price change privileges reserved .
Copyright c
1974 by Tektronix, Inc .,
Beaverton,
Oregon
. Printed in the
United
States of America . All
rights reserved . Contents of this publication may not
be reproduced in any form without permission of
Tektronix, Inc .
U .S .A
. and foreign TEKTRONIX products covered
by U .S . and foreign patents and/or patents pending .
TEKTRONIX is a registered trademark of Tektronix,
I

TABLE
OF CONTENTS
SECTION 1 GENERAL INFORMATION
&
SPECIFICATIONS Page
Electrical Characteristics 1-2
Environmental Characteristics 1-4
Accessories
SECTION 2 OPERATING INSTRUCTIONS
Introduction 2-1
Function of the Front Panel Controls .
Operational Check 2-5
Using the Analyzer
2-9
Signal Application
Resolution, Sensitivity, and Frequency Span 2-10
Gain Desensitization Near 0 Hz
2-11
Using the Video Filter
Selecting Sweep Rate
Triggering the
Display 2-12
Manual Scan of the Spectrum
How to Use an External Sweep Source
External Trigger Operation
Using the CAL OUT
Signal
Reference
for Accurate
Frequency and Amplitude Measurements 2-13
Using the Analyzer Below 100 kHz 2-14
SECTION 3
PERFORMANCE CHECK
Operational Performance and Instrument Familiarization 3-1
Equipment Required
Preliminary Preparation
Check the 10 dB/Div and LIN Mode Calibration
Check
the Frequency Readout Accuracy 3-2
Check the Range of the REF VAR Control, the
Range and Accuracy of the Gain Selector, and
the Gain Accuracy of the 10 dB Pushbutton
Check the Operation of the Video Filters 3-3
Check
Sensitivity
Check Spurious Signals from Internal Sources
(Residual Responses)
3-5
Check Resolution Bandwidth and Shape Factor
Check Incidental Wing 3-6
Check Sweep Circuit Operation with the TIME/DIV in the
MANUAL, and OFF Positions 3-7
Performance Checks
Requiring Test Equipment
Equipment Required
Check the Calibrator Frequency 3-9
Check Calibrator Output Level
Check RF Attenuator Accuracy 3-10
Check Display Flatness
Check
Intermodulation Distortion 3-11
Check Pulse Stretcher Operation 3-12
Check Triggering Operation and Sensitivity 3-13
Check The External Horizontal Input Voltage Requirement 3-14
Check the Video Output Level
3-15
Check
Frequency
Span
Accuracy and Linearity
Check Time/Div Accuracy 3-16

TABLE OF CONTENTS (cont)
SECTION 4
SECTION 5
CALIBRATION Page
Equipment Required
4-1
Short Form Procedure and Record
Time Base Section
Adjust Sweep Length, Offset, and Triggering 4-3
Function IF Alignment 4-6
Adjust the LIN
Mode Baseline Offset
Adjust the Gain Compensation
and
Calibrate the
Reference Level
1st LO Phase Lock Loop
Error Amplifier Offset Adjustment 4-8
Frequency Span and 1st LO Calibration
Adjust the
Frequency Span of the 1st LO and the
16-19 MHz
Oscillators
Calibrate the Center Frequency and Frequency Readout 4-10
Phase Lock Calibration Adjustments
Adjust Memory Gain
4-11
Adjust Error Amplifier Gain
Resolution
Adjust the Bandpass of the 105 MHz IF Amplifier
and
300 kHz Filter
4-12
Adjust the Resolution Gain Leveling Compensation 4-14
Adjust the Post Resolution Amplifier Gain
4-16
Minimize Intermodulation Products
50 MHz Calibrator
Adjust the
Calibrator Output
CIRCUIT DESCRIPTION
Block Diagram Description 5-1
Detailed Circuit Description
5-2
RF
or
Microwave
Circuits
Phase Lock and Frequency Stablization 5-3
YIG Driver, Voltage Memory and Phase Lock Logic 5-4
Frequency Tuning Control and Readout 5-5
Tuning
Control
YIG Driver
Frequency Span 5-6
Marker Generator
105 MHz
IF Amplifier, 3rd Mixer and Oscillator
10 MHz IF Pre-resolution Amplifier and
Resolution Filter Circuits
YIG Oscillator Power Supply 5-7
30
Hz Filter
50 MHz Calibrator
Function IF Amplifier
Video
Filter,
Pulse stretcher, Baseline Clipper
& Vertical Output 5-8
Frequency Readout 5-9
Uncal Circuit
5-11
Sweep Triggering Sweep Generator and
Horizontal Amplifiers 5-12

TABLE
OF
CONTENTS (cont)
CHANGE INFORMATION
SECTION 6 MAINTENANCE INSTRUCTIONS Page
Preventive Maintenance 6-1
Cleaning
Lubrication
Visual Inspection
Transistor and Integrated Circuit Checks
Performance Checks and Recalibration
Troubleshooting 6-2
Troubleshooting Aids
Diagrams
Circuit
Board
Illustrations
Wiring Color Code
Multiple Terminal (Harmonic) Connector Holders
Resistor Code
Capacitor Marking
Diode Color Code
Transistor and Integrated Circuit Electrode Configuration
Diode Checks 6-3
IC Checks
General Troubleshooting Techinque
Corrective Maintenance 6-5
Obtaining
Replacement
Parts
Repair and Exchange Program
Soldering Technique
Replacing Square Pins for Multi-pin Connectors 6-6
Replacing Assemblies
Front Panel Controls and Selectors
Circuit Board Assemblies 6-8
DVM Logic and Readout Circuit Board
Replacing the Sweep Circuit Board
Replacing the IF Function Circuit Board 6-10
Replacing the Resolution Circuit Board
Replacing
Circuit Boards in the Honeycomb Assembly
Replacing Microwave Assemblies
Replacing the 2 .095 GHz Filter Assembly A10,
or the Multiplier-Bandpass Filter A401 6-11
Replacing the Multipler 2 .18 GHz Bandpass
Filter and 16-19 MHz Mixer Circuit Board Assembly 6-13
SECTION 7 OPTIONS AND MODIFICATIONS
SECTION 8 ELECTRICAL PARTS LIST
SECTION 9 DIAGRAMS AND CIRCUIT BOARD ILLUSTRATIONS
SECTION 10 MECHANICAL PARTS LIST

Fig . 1-1 . 71-13 Spectrum Analyzer .

INTRODUCTION
GENERAL INFORMATION
AND
SPECIFICATIONS
Abbreviations used in the text and
diagrams are based
on
ANSI Y 1 .1, 1972 Standards . This manual is divided into
ten major sections that provide the following information :
Section
1 - General Information and Specifications :
Contains the instrument description and specifications .
Section 2 - Operation Instructions : Information
relative to installing and operating the instrument .
Section 3 - Performance Check : Provides procedures
to check the operational performance of the instrument
plus additional performance check procedures that re-
quire test equipment to verify that instrument perfor-
mance is in accordance to specifications .
Section 4 - Calibration Procedure : Describes test
equipment setup and adjustment procedures required to
calibrate the instrument .
Section 5 - Circuit Description : Provides basic and
general circuit analysis
that
may be useful
when servicing
or operating the instrument .
Section 6 - Maintenance Instructions : Describes
routine
and
corrective maintenance procedures with
detailed instructions for replacing assemblies, sub-
assemblies, and individual components . Troubleshooting
procedures, plus general information that may aid in
servicing the instrument, are also provided . An exploded
drawing is part of Section 10 .
Section 7 - Options : Describes options available for
the instrument .
Section 8 - Electrical Parts List : Provides
information
necessary to order replaceable parts and assemblies .
Section 9 - Diagrams : Provides functional block
diagram and detailed circuit schematics . Located adja-
cent to the diagram (usually on the back of the preceding
diagram) are pictoral layout drawings that show sub-
Section 1-71-13
assembly and component locations . IC logic diagrams,
waveforms and voltage data, for troubleshooting orcircuit
analysis, are also provided adjacent to or on the diagram
.
Section 10 - Mechanical Parts List, Exploded
Drawings and Accessories : Provides information
necessary to order replaceable parts . The Parts List is
cross-referenced to the Electrical Parts List . Exploded
drawing shows sequence of assembly and identifies
assemblies .
Changes and Corrections : Provides updating informa-
tion
for
the manual
in
the
form
of inserts
. These inserts are
incorporated
into the
manual
text and diagrams when the
manual is reprinted .
DESCRIPTION
The 71-13 Spectrum Analyzer is a high-performance
communication
spectrum
analyzer that plugs into and
operates with the 7000-Series mainframe oscilloscopes . It
is a swept front end analyzer that displays absolute
amplitude
information
of
signals within the frequency
span of 0 Hz to 1 .8 GHz . Time domain characteristics,
within a 3 MHz bandpass, can also be displayed .
Important features of
the 71-13
are :
1) Greater than
70 dB dynamic range . 2) Sensitivity down to
-128 dBm .
3) Resolution capability from 3 MHz to 30 Hz .
4) Incidental Wing less than 10 Hz . 5) Fully calibrated
display modes of either 10 dB/Div, 2 dB/Div, or Linear ;
and a calibrated reference level in dBm . 6) Calibrated
sweep spans from 100 MHz/Div to 200 Hz/Div . 7) Digital
frequency readout . 8)
Full
range of
video filtering for noise
averaging . 9) Baseline clipping to subdue the bright
baseline of displays when photographing . 10) Pulse
stretching, to enhance pulsed spectra when
using
wide
frequency spans and resolution bandwidths .
11)
Access
for a tracking generator . 12) Frequency and amplitude
reference calibrator .
If the 7000-Series mainframe features crt readout, the
signal
parameters and
other pertinent information, such
as resolution bandwidth, video filtering, and frequency
span, are displayed on the crt readout to simplify the
operation of the instrument . Records can then be made of
pertinent data by
photographing the display .

Specification-7L13
The analyzer requires three plug-in widths in the 7000-
Series mainframe .
The following characteristics
and
features of
the 7L13
Spectrum
Analyzer are applicable after a warmup period
of 30 minutes or more .
CENTER
FREQUENCY
Resolution of the Center Frequency Indicator : Within
1 MHz .
The center frequency is indicated by LED readout on
the 7L13 and crt readout when the 7000-Series mainframe
has this feature .
FREQUENCY SPAN
Calibrated spans from 200 Hz/Div to 100 MHz/Div in a
1-2-5 sequence, plus O Hz and MAX SPAN positions . In the
0 Hz position, the analyzer is a fixed tuned receiver for
time domain analysis . In the MAX SPAN position the
frequency span
is approximately 1
.8 GHz .
Accuracy : Within 5%of the indicated frequency separa-
tion . Linearity over the center 8 divisions is within
5%
.
RESOLUTION
Six resolution bandwidth selections from 30 Hz to
3 MHz, in decade steps, are provided . Resolution
bandwidth may
be coupled or uncoupled from the fre-
quency span selector .
Bandwidth accuracy : Resolution bandwidth, at the
6 dB down point, is within
20% of
the
resolution selected .
Shape factor (60 :6 dB ratio) : 12 :1 or better for 30 Hz
resolution and 4 :1 or better with resolution of 300 Hz or
more except 3 MHz . Maximum bandwidth 60 dB down
with 3 MHz resolution, is 13 MHz .
Signal level change over the
six resolution bandwidth
selections is less than 0 .5 dB .
ELECTRICAL
CHARACTERISTICS
Range : 1 kHz to 1 .8 GHz .
Accuracy : f(5 MHz + 20% of the Freq Span/Div) .
STABILITY (after a 2 hour warmup period)
Within 2 kHz per hour at a fixed temperature, when '^
phase locked ; within 50 kHz when not phase locked .
INCIDENTAL FM (see Fig .
3-5)
10 Hz (peak-to-peak) or less when phase locked, and
10
kHz
(peak-to-peak) or less
for
5 seconds when out of
phase locked mode .
VIDEO FILTERING
Three selections of video filtering ; 10 Hz, 300 Hz
and
30 kHz are provided for signal or noise averaging .
DISPLAY
LOG 10 dB/DIV : Provides a calibrated 70 dB dynamic
range with an
accuracy that is within 0 .1 dB/1 dB to a
maximum of 1 .5 dB over the full dynamic range .
LOG 2 dB/DIV : Provides a calibrated 14 dB dynamic
range with an accuracy that
is
within t0
.4
dB/2 dB
to a
maximum of 1 .0 dB over the 14 dB dynamic range .
LIN : Provides a linear display from approximately
0 .7 /jV (100 dBm) full scale, to 7 .07 volts
(+30
dBm) .
Amplitude linearity is within 10% over the graticule height .
REFERENCE LEVEL
Reference level operation is in calibrated 10 dB steps
from -110 dBm
to +30 dBm,
within
t2 dB
.
(Accuracy
includes the attenuator and gain switching effects when
the two
are not offsetting each other .) Reference level
operation below 100 kHz becomes limited to a rangefrom
+30 dBm to-50 dBm as the center frequency approaches
1 kHz .
Reference level deviation,
between display modes, is
less than 2 dB from 2 dB/DIV to 10 dB/DIV and less than
0 .5 divisions from 2 dB/DIV to LIN . This deviation is a
function
of the oscilloscope vertical linearity .
An LINCAL indicator signifies when
the display is not
calibrated .
DISPLAY FLATNESS
+1 dB, -2 dB with respect
to
the level at 50 MHz, over
any selected frequency span .

CALIBRATOR
50 MHz ±0 .01% with an absolute amplitude level of
-30 dBm ±0 .3 dB, at 25°C . 50 MHz harmonics are
generated to provide a comb of
markers for
frequency
span calibration .
CW
SENSITIVITY (Signal
+
noise
=
2x noise, In LIN
display mode)
The following characteristics are applicable from
100 kHz to 1 .8 GHz : Below 100 kHz the sensitivity
degrades approximately 0 .3 dB/kHz ; for example, the
sensitivity at 50 kHz with 30 Hz resolution is, -113 dBm or
better ; at 1 kHz, -98 dBm or better .
SPURIOUS SIGNALS FROM INTERNAL SOURCES
(Residual
Response)
Equal
to or less than -100 dBm, referred to the 1st
mixer input .
INTERMODULATION DISTORTION (Fig . 3-6)
100
kHz -
1 .8 GHz : Third order intermodulation
products
are
down 70 dB or more from two -30 dBm
signals within any frequency span, second order products
are down 70 dB or more from two -40 dBm signals within
any frequency span .
100 kHz - 1 kHz : Intermodulation products (3rd and
2nd) are down 50 dB or more for the same input level as
above .
GAIN
The gain range is 80 dB total . An eight position selector
changes the IF gain 70 dB in 10 dB (±1 .0 dB) steps and a
10
dB pushbutton
adds an
additional
10
dB
of
gain when
the REFERENCE LEVEL is -100 dBm and 30 Hz resolu-
tion bandwidth is used, in the 2 dB/DIV or LIN mode .
Four positions (blue sector) of the selector provide
30 dB of change in all display modes . The remaining four
RFATTENUATOR
NOTE
SWEEP MODES AND RATE
TRIGGERING
Specification-7L13
positions provide an additional 40 dB of gain only in the
2
dB/DIV and LIN modes . The 10 dB pushbutton provides
the
additional 10 dB of gain, when the resolution bandwith
is 30 Hz and the REFERENCE LEVEL
is -100
dBm in
the
2 dB/DIV or LIN mode .
The REF VARiable control provides
continuous
gain
adjustment between each calibrated REFERENCE LEVEL
setting .
Provides 60 dB of attenuation in
calibrated 10 dB steps .
Accuracy is ±0 .2 dB or 1 % of the dB reading, whichever is
greater
.
The maximum input power level
to
the
RFA ttenuator
is 1 watt average and 200 watts peak . +13 dBm will
destroy the 1st mixer .
Selection of an external sweep source, manual sweep,
or calibrated sweep rates from 10 s/Div to 1 ps/Div in a 1-
2-5 sequence are provided . Sweep rate accuracy is within
5% of that selected .
Three triggering sources can
be selected .
INTernal
selects the vertical or video component from either vertical
plug-in
compartment, EXTernal selects the signal applied
to the EXT IN HORIZ/TRIG connector and LINE selects a
sample of the mainframe line voltage
.
INTernal signal
is ac
coupled with an approximate frequency range from 15 Hz
to 1 MHz . The external and line signals are do coupled .
Input
impedance for the external input is about 30 kid for
the trigger
mode and 9 kQ for external horizontal sweep
mode .
Trigger sensitivities are : 1)
<0
.5 division of internal
signal (peak-to-peak) and <0 .5 volt of signal (peak-to-
peak) of external signal for NORM mode . 2) <0 .5 division
of
internal signal
peak-to-peak and <0 .5 volt of external
signal for SGL SWP mode .
RESOLUTION BANDWIDTH SIGNAL LEVEL
30 Hz -128 dBm
300 Hz -120 dBm
MAXIMUM INPUT POWER LEVEL
3 kHz -110 dBm
30 kHz -100 dBm
-30
dBm with the
RF Attenuator at 0 dB, for linear
.3 MHz -90 dBm
operation, +30 dBm with the RF
Attenuator at 60 dB .
3 MHz -80 dBm
(+30 dBm is
also
the
power
rating of
the RF Attenuator .)

Specification-71-13
In the NORM mode
the sweep will automatically recur
at
the end of holdoff time if a trigger signal
is absent, to
provide a baseline on
the crt .
The SGL SWP and "start"
buttons function together to
provide a single sweep
each time the "start" button is
pushed .
VIDEO
OUTPUT CONNECTOR
Provides 50 mV t5%
of video signal per display
division, about the
crt vertical center . Source impedance is
approximately
1 kit . A maximum of 50 mV offset
may be
introduced by
the error from the
mainframe vertical
centering interface .
EXTERNAL
HORIZONTAL/TRIGGER INPUT
CONNECTOR
Requires 0 V to 10 V t1
V, to sweep the full frequency
span .
Requires 0 .5 volt peak-to-peak
to trigger the sweep
circuits .
Maximum safe input ; 50 volts (dc + peak ac) .
ENVIRONMENTAL CHARACTERISTICS
This instrument
will meet the electrical characteristics
over
the environmental limits of the 7000-Series
main-
frame . Complete details on test procedures,
including
failure criteria, etc ., can be obtained
from Tektronix, Inc .
Contract your local
Tektronix Field Office or represen-
tative .
ACCESSORIES AND OPTIONS
STANDARD ACCESSORIES
1 . Spectrum Analyzer
Graticule : Clear plastic implo-
sion shield
with
LOG,
LIN, REF and f (frequency)
direction
markings . Tektronix Part No .
337-1439-01 for 7403N
oscilloscope and 337-1159-02
for other 7000-Series os-
cilloscopes .
attenuator with DC block
OPTIONS TO 7000-SERIES
OSCILLOSCOPES
1 . CRT with P7 phosphor and time
domain graticule .
The external graticule
for spectrum analysis (part of
standard accessories) should be
used .
2 . CRT with P7 phosphor and an
internal spectrum
analyzer graticule (designated
P7SA) . This is
recommended when the oscilloscope
mainframe is to be
used exclusively with spectrum
analyzer systems .
2 . Filter
Light Amber 378-0684-01
3 .
50 i2 Coaxial Cable,
012-0113-00
with BNC connectors,
6 foot
4 . BNC Male to
N Female Adapter 103-0058-00
5 . Manual
070-1673-00
OPTIONAL ACCESSORIES
1 . DC Block (for
applying 015-0221-00
signals
riding on a DC poten-
tial) . Maximum potential is
50VDC
2 . 75 0 to 50 i2 minimum loss
011-0112-00

INTRODUCTION
OPERATING
INSTRUCTIONS
This section describes : 1) Function
of
the
front panel
controls, selectors, indicators and connectors
.
2) Installation
of the 71-13 into a 7000-Series oscilloscope
.
3) General
operation information, such as : Adjustments
required to mate the 71-13 to a
7000-Series oscilloscope .
Signal application to the RF
INput
.
How to use the
calibrator for accurate frequency and
power level
measurements, etc . 4) Some typical applications
.'
The first steps of the General
Operating information
calibrate and check the analyzer Frequency,
Span/Div,
and the display modes .
These steps serve as part of an
acceptance
check and describe how to obtain a display
on
the oscilloscope crt .
Performing this Operational Checkout
procedure will
acquaint you with the
functions of the controls and
selectors and the overall
operation of the 71-13 .
FREQUENCY
CONTROLS
A
safety latch must be released before the 71-13
can
be pulled from the
oscilloscope compartment . The
unit will pull out part way,
when the front panel
release is pulled, then the spring
safety latch must be
pushed up to free the unit so it can
be pulled the rest
of
the
way out . This safety latch is located un-
derneath the right rail
near the front corner (see
Fig . 2-113) .
FUNCTION OF THE
FRONT PANEL
CONTROLS AND ADJUSTMENTS
The following is a general
description of the 71-13
controls, indicators and connectors . This description will
familiarize
you
with
theirfunction and Figs . 2-1Aand 2-1 B
illustrate their
location .
TUNING : The center frequency is tuned by a
two-speed
control with a ratio
of approximately 1 :2 .8 in the position
and 45 :1 in the slow orfine
position . In addition, the tuning
range
is decreased to 1 MHz (±9500 kHz) when the
FREQ
SPAN/DIV is 50 kHz or
less .
I A treatise on spectrum analyzer
measurements and applications
Is contained In
Tektronix Measurements Concepts Booklet ;
"Spectrum Analyzer Measurement Theory and
Practice :", Part
No . 082-1334-00 .
A MARKER indicator lights when the FREQ SPAN/DIV
is at the MAX SPAN position
and a notch on the baseline of
the display
indicates the center portion of the span that
will be displayed when the
FREQ SPAN/DIV is reduced .
The center frequency
or
marker frequency
is indicated
by an LED digital readout dial .
CAL : Calibrates the frequency
readout so it represents
the center of the span .
NOTE
When operating with
Freq Spans of 50 kHz/Div or
less, the AUTO PHASE
LOCKED switch must be
OFF if you want the center frequency
and LED
readout to change when tuning .
FREQ SPAN/DIV : This switch selects the
frequency
span of the display . The
calibrated range of the selector is
100 MHz/DIV to 200 Hz/DIV in a 1, 2,
5 sequence .
A
MAX
SPAN position
provides approximately 1 .8 GHz of spec-
trum
and a 0 Hz position converts the analyzer to a fixed
tuned receiver for time domain
displays . Time analysis of
the signal characteristics, within the bandwidth
capabilities selected with the
RESOLUTION control, can
then be
performed .
Section 2-71-13
The FREQ
SPAN/DIV knob is large enough to
provide ease in switching ; however,
excess torque
applied when the selector is at either
of
its extreme
positions may cause the aluminum bushing inside
the
knob to slip . When this occurs, the selectors may
double detent
or
switch
with a grinding noise . Refer
to Knob Removal and Installation instructions
in the
Maintenance section of the manual for realignment .
RESOLUTION : This control selects the
resolution
bandwidth for the
analyzer . The calibrated range (within
20%) is 30 Hz to 3 MHz in decade steps . The
RESOLUTION is normally coupled to the FREQ
SPAN/DIV control
so the display amplitude remains
constant as
the FREQ SPAN is changed ; however, a
concentric sleeve labeled PULL TO UNLOCK will uncou-
ple the two
selectors when it is pulled out and allow
independent settings of each control .

Operating Instructions-7L13
Fig . 2- 1 A . Front panel controls and selectors .

Fig
.
2-28
.
Front panel controls and selectors .
Operating Instructions-7L13
2-3

Operating Instructions-71 .13
DISPLAY CONTROLS AND
SELECTORS
LOG 10 dB/DIV : Selects a calibrated display with a
dynamic range of 70 dB (to the7th graticule line, from the
reference) at 10 dB/DIV . The bottom graticule division is
not calibrated
.
LOG 2 dB/DIV : When this pushbutton is depressed, the
dynamic range of the display is a calibrated 14 dB at
2 dB/DIV .
LIN : Selects a linear display . The LIN graticule calibra-
tion permits relative signal level measurements as follows :
Adjust the level of one signal
to
the
1 .0 line, with thegain or
RF Attenuation . Read the level of the other signals as a
percentage of this reference .
REFERENCE LEVEL (RF
Attenuator and IF Gain) :
These are concentric controls that are connected in an
electro-mechanical differential arrangement . They select
input attenuation
to
the input
mixer, and the IF gain . They
indicate, via readout windows ; REFERENCE LEVEL in
dBm, of the full scale display, MAXimum signal input
level
(in dBm) for linear operation, and the input RF attenuation
(from
0 to 60 dB) .
The RF attenuation is in series with the input signal path
to the input
mixer, therefore its settings affect the
maximum input signal level
to
the 71-13
. With 0 dB
attenuation, maximim input signal level for linear opera-
tion, is -30 dBm . Changing the RF Attenuator to 60 dB
increases the maximum input
signal level to +30 dBm .
The IF gain selector has a range of 70 dB in
10 dB steps .
The
combination of RF Attenuator and IF gain settings
establishes the REFERENCE LEVEL
; therefore, both
controls function as REFERENCE LEVEL selectors . The
maximum sensitivity of the display will not exceed
-130 dBm .
Since the dynamic window is 70 dB in the
10 dB/DIV display mode, the REFERENCE
LEVEL
readout is valid to -60 dBm . With the RF Attenuator at
0 dB and the IF gain fully
ccw, the REFERENCE LEVEL is
-30 dBm . Increasing the IF gain 30 dB, changes the
REFERENCE LEVEL
to -60 dBm, which is the limit for a
calibrated reference level in the10
dB/DIV mode . The blue
tint, that borders the 10 dB/DIV switch and four positions
of the gain selector, correlates REFERENCE LEVEL
readout to the gain settings applicable in the 10 dB/DIV
mode
.
Readings,
with the gain selector outside the blue
tint sector are erroneous
because the gain is electrically
locked out ; the crt readout will display the <
symbol to
signify that the reading is incorrect .
In the 2 dB/DIV mode, the full 70 dB range of the gain
selector is usable . Switching the
gain fully cw with the RF
Attenuator at 0 dB, produces an accurate
-100 dBm
2-4
reference level . The
dynamic
range
of the display is now
-114 dBm (-100 dBm + 14 dB display window to the 7th
graticule
line) . An additional 10 dB of gain, fora calibrated
-124 dBm, can be switched in with the 10 dB GAIN
pushbutton,
when
the RESOLUTION is 30 Hz .
VIDEO FILTERS
: Three filters (30 kHz, 300 Hz, and
10 Hz) can
be switched in to restrict the video bandwidth
and reduce high frequency components for display
noise
averaging . Two pushbuttons select 30 kHz or 300 Hz
when depressed, and 10 Hz when both are depressed .
BASELINE CLIPPER : This
controls the vertical
amplitude of that portion (baseline plus signal) of the
display that the intensity is subdued .
CONTRAST : Adjusts the brightness ratio between the
clipped
(subdued) baseline and the unclipped display .
The display intensity is set by the mainframe Intensity
control .
PULSE STRETCHER : Switching this on, stretches the
falltime of pulsed signals to enhance the visibility
of
pulsed RF signals that may be within wide frequency
spans and resolution bandwidths
.
LOG and AMP CAL : The
LOG adjustment calibrates the
logarithmic accuracy of the display . The AMP adjusts the
REFERENCE
LEVEL to the top graticule line .
AUTO PHASE LOCKED : This switch is used to disable
the phase lock for some applications, such as tuning the
analyzer more than 1 MHz when the analyzer is used as a
tuned receiver (0 span) .
VERTICAL
POSITION : Positions the crt beam ver-
tically .
HORIZ POSITION : Positions the crt beam horizontally .
OUTPUT
AND INPUT CONNECTORS
VIDEO OUT : Provides ±50 mV of video per displayed
division of signal . The amplitude and polarity of this signal
is relative to the graticule vertical centerline . Source
impedance is about 1 kf2 . This signal can
be used to
drive
an external device such as a recorder .
TRACK GEN : A source of control signals for a Tracking
Generator . Pin 5of the connector is the source of a +10 V
to -10 V sweep ramp, with +10 V representing the
left
edge of the display and -10 V the right side of the display .

RF IN : A 50 f2 input connector for applying the input
signal to the 71-13 . REFERENCE LEVEL readout refers to
the signal level at this connector
. Any signals riding on
some do
potential must be applied through a do block .
Refer to the General Operating Procedure with regard to
signal
applications .
1st and 2nd LO OUT : These connectors provide access
to the output of
the respective local oscillators . They must
be
terminated into 50 O . Keep the termination plugs on the
output jacks unless
these ports are connected to an
external device such as a tracking generator .
CAL OUT : Provides an accurate -30 dBm, 50 MHz
signal source . This signal provides an absolute reference
on the display to calibrate the REFERENCE LEVEL and
check dBm readings .
Harmonics
of
the 50 MHz fun-
damental provide a comb of markers across the frequency
span for accurate frequency and span measurements .
SWEEP CONTROLS
TRIGGERING SOURCE : Three sweep triggering
sources can be selected plus a free run mode : INTernal
selects the vertical orvideo component from eithervertical
plug-in compartment . The signal is ac coupled with an
approximate frequency range from 15 Hz to 1 MHz ;
EXTernal selects the signal that is applied to the EXT IN
HORIZ/TRIG connector ; and LINE selects a sample of the
mainframe
line
voltage .
External and line signals are do
coupled
to the triggering circuits . Maximum signal input
to the external input connector should not exceed 50 volt
(dc + ac peak) for triggering . Input impedance for the
external input is about 30 kf2 .
The FREE RUN mode will not sync the sweep to any
triggering signal .
MODE : Two modes are available, NORM and SGL
SWP . In the NORM mode the sweep will automatically
recur at
the
end of
holdoff time, if a trigger signal is absent .
This feature provides a baseline on the display . In this
mode triggering occurs at the slope and level selected by
the SLOPE/LEVEL controls unless the triggering signal is
below the required amplitude or beyond the frequency
limits of
the
circuit .
Minimum signal amplitudefor internal
triggering is 0 .5 division of signal (peak-to-peak) and
0 .5 volt of signal for external triggering .
In the SGL SWP mode, the sweep is triggered by
pushing the adjoining button . This button lights during
sweep time and serves as an indicator to determine
camera shutter time when photographing slow scan-time
displays . Minimum signal amplitude
for triggering
is
0 .5 division of signal and 0 .5 volt of external signal .
OPERATIONAL CHECK
NOTE
Operating Instructions-71 .13
TIME/DIV and
MANUAL SCAN : Three sweep modes,
plus an off state, are provided
: A calibrated TIME/DIV in a
1, 2, 5
sequence from 10 s/DIV to 1 Ns/DIV, a manual
sweep control, and an external sweep .
The TIME/DIV
control selects the sweep
rates and the modes .
In the OFF position, the
crt
beam
is horizontally
centered and the analyzer
becomes a fixed tuned receiver
at the frequency
indicated by the readout .
The EXT position connects any signal applied to the
EXT/HORIZ TRIG connector to the horizontal deflection
circuits of the 71-13 . External sweep
voltage (0 V to 10 V)
signal can be used to
slave the 71 .13 to an external device
such as a recorder
.
The
MANUAL position connects the sweep circuits of
the 71-13 to the MANUAL SCAN control, so the crt beam
deflection can be manually controlled .
SWEEP CAL : The adjustment calibrates the amplitude
of the sweep voltage to the FREQ SPAN circuits and
compensates for differences in deflection sensitivities
between oscilloscopes .
1 . Preliminary Operational Procedure
that
Calibrates the 71-13 to the Osciliscope
Mainframe
When the 71_13 plug-in unit is installed in a7000-Series
mainframe, the spectrum analyzer
should be calibrated to
ensure correlation between plug-in
and the mainframe
deflection sensitivities . We recommend
that the front
panel calibration
procedure be performed anytime the
instrument
is
first turned on, to ensure optimum accuracy .
a . Plug the 71-13 Spectrum
Analyzer into the 7000-
Series
mainframe . Ensure that the 71-13 is securely latched
in the compartment . This is a safeguard to ensure
that the
instrument
does not slide out,
if the mainframe is tipped
forward .
A safety
latch is used to reduce the possibility of the
instrument slipping out of the mainframe .
b . Connect the oscilloscope mainframe to a suitable
power source and switch the power on . Allow about
30
minutes for instrument stablization
.
2- 5

2- 6
Operating Instructions-71 .13
c .

Set the front panel controls as illustrated in Fig . 2-2
and connect the CAL OUT signal through a short coaxial
cable to the RF INput
.
d . Adjust the oscilloscope Intensity, Focus and
Astigmatism controls
for
optimum display definition with
normal intensity .
e . Depress the 2 dB/DIV display mode button . Posi-
tion the baseline of the display to the bottom graticule line
with the VERTICAL POSITION control and center the
display
with
the
HORIZ
POSITION control .
f . Depress the 10 dB/DIV (LOG) display button .
Display should now resemble that shown in Fig . 2-2 .
NOTE
When the
oscilloscope has a crt with P7 phosphor, a
viewing
hood will help shield ambient light
and
enhance the display information .
2 .
Calibrate the Frequency Readout
Due to hysteresis in the tuning system, the calibration
and accuracy of the readout must be performed and
checked by approaching
each check point from the same
direction (low to high) .
a . Apply the calibrator signal to the RF INput, switch
the
FREQ SPAN/DIV to MAX SPAN, and tune the CENTER
FREQUENCY to 0000 .
b . Decrease the FREQ SPAN/DIV setting
to 10
MHz
and increase the CENTER FREQUENCY until the 50 MHz
calibrator signal is tuned to the centerl ine of the graticule .
NOTE
It is important
to tune
the signal
from low to high . If
the tuning direction is reversed, repeat the
procedure by returning the FREQ SPAN/DIV to MAX
SPAN and the CENTER FREQUENCY to 0000 to
establish the same reference point on the hysteresis
loop .
c . When the 50 MHz signal is centered on screen,
adjust
the frequency CAL for a CENTER
FREQUENCY
readout of 50 MHz .
3 . Calibrate the Sweep Span
a . Switch the FREQ SPAN/DIV to MAX SPAN position .
b . Position the 0 Hz response, or LO feedthrough, on
the zero
(left) graticule line with the HORIZ POSITION
control .
c .
With the CAL
OUT
signal
applied to
the RF INput,
decrease the FREQ SPAN/DIV to 50 MHz and tune the 5th
marker (250 MHz) to the center graticule line (see Fig . 2-
3) .
d .
Calibrate the
frequency span to 50
MHz/DIV
by
adjusting the SWP CAL for 1 marker/division . It may be
necessary to keep the 250 MHz marker centered with the
frequency
TUNING
control as
the
sweep is calibrated .
Final display should resemble that illustrated in Fig . 2-3 .
4 . Check and Adjust LOG-AMPL Calibration
The LOG CAL adjustment calibrates the gain of the
analyzer
vertical output so the 2
dB/DIV
and 10
dB/DIV
modes
may
be accurately
set . The AMPL CAL adjustment
sets the reference level to thetop graticule line . There is no
interaction between these two, adjustments .
a . Set the 71-13 selectors and controls as directed in
step 2 and tune the fundamental 50 MHz calibrator signal
to the center of the graticule .
b . Uncouple the RESOLUTION selector from the
FREQ SPAN/DIV by
pulling
out the
PULL
TO UNLOCK
sleeve, then switch the FREQ SPAN/DIV to 5 MHz . The
RESOLUTION should remain at 3 MHz . As the FREQ
SPAN
is decreased, it may be necessary to re-adjust the
tuning control to keep the signal centered on screen .
c . Switch the Display Mode to 2 dB/DIV and position
the
baseline of the display on the bottom gratiucle
line
with the VERTICAL POSITION .
d . Adjust
the
AMPL CAL and the LOG
CAL (if
necessary) to
bring
the 50
MHz signal within the
graticule
window . Adjust the AMPL CAL to establish a signal
reference amplitude of 8 divisions (Fig . 2-4 shows a full
screen display) .
e . Switch

in

10 dB

of attenuation with the RF

'~
Attenuator . Amplitude change should equal 5 divisions at

-
2 dB/DIV .

Operating Instructions-71-13
Top line is dBm level
indicated by REFERENCE
LEVEL window and
Readout .
Display Mode : 10 dB/DIV
Frequency : 250 MHz
UNCAL Light
OUT
RF Attenuator : 0 dB
CENTER
FREQUENCY
RESOLUTION
Termination caps on

CAL OUT : Connect to
Output Ports

RF
Input
PULSE STRETCHER Out
Sleeve
pushed in so
FREQ
SPAN/DIV and
RESOLUTION are
coupled
together .
FREQ
SPAN/DIV : 50 MHz
Fig . 2-2 . Front panel selector positions and
signal connections for initial operational check and front panel calibration .

Operating Instructions-71-13
Set the 250 MHz (5th) marker at
0
Hz response

the centerline with the HORIZ
POSITION
control .
I "M IM,
11

11

1I1
"

,s'~
1
,ll,

ll~"
0 J

1
MHz , pz I-Jodam
Fig . 2-3 . Calibrating
the sweep span .
40
-so
050 -J(~dDm
1)
Adjust
LOG CAL for
10 dB amplitude
change
with 10 dB
change in
RF Attenuator .
2) Adjust AMP CAL to
position -30 dBm signal
to the REFERENCE
LEVEL (top graticule
line) .
_

__
T
__ -

,
k,
J ~MHZI Ai:S
Baseline of the display
must be
positioned on
the bottom
graticule line .
Fig . 2-4 . Calibrating the LOG and REFERENCE LEVEL
. (Double
exposure to illustrate the relationship of the two displays .)
f . If the change is more than 5 divisions
(e .g .,
amplitude decreases from 8 to 2 .5 div), adjust LOG CAL
to
further increase the amplitude change (i .e ., decrease the
signal amplitude)
.
Conversely, if
the change is less than
5 divisions (e .g ., amplitude changes from 8 to . 3 .5 div),
adjust the LOG CAL to further decrease the amplitude
change (i
.e ., increase
the
signal amplitude) . Correct for
approximately 1/2 the total indicated error . This
adjust-
ment may seem opposite to what is expected ; however, the
LOG CAL adjustment also shifts the reference level . This,
therefore will require a correction
to the amplitude
change .
2- 8
g . Switch out the 10 dB of RF Attenuation . Now adjust
the AMPL CAL to return the signal level to the reference
line . (Ensure that the baseline of the display is still on the
bottom graticule
line
.)
h . Repeat these steps until the 2 dB/DIV display is
calibrated (see Fig . 2-4), then return the RF Attenuator to
0 dB (REFERENCE LEVEL -30 dBm) . Ensure that the
-30 dBm signal is 8 divisions
in amplitude
.
NOTE
An alternate method of calibrating the display is to
switch between the 10 d8/DIVand2 d8/DIVdisplay
modes while adjusting the LOG CAL so the display
amplitudes are equal, then adjust the AMPL CAL so
the display amplitude, in 2 d8/DIV mode, equals
-30 dBm reference . Check the final calibration in
the 2 d8/DIV
mode .
i . Switch the display modes from 2 dB/DIV to
10
dB/DIV, then from 2 dB/DIV to LIN . Signal amplitude
reference level should not change more than 2 dB from
2 dB/DIV
to 10 dB/DIV, or 0 .5
division from 2
dB/DIV to
LIN mode .
5 . Check the 10 dB/DIV and LIN Mode Display
Operation
a . After completing the LOG CAL and AMPL CAL
adjustments, described in step 4, depress the 10 dB/DIV
button . Ensure that the RF Attenuator is at 0 dB and the
Gain selector is fully ccw so the REFERENCE LEVEL
reads -30 dBm .
b . Switch the FREQ SPAN/DIV to 1 MHz and the
RESOLUTION to .3 MHz . Tune the 50 MHz marker to the
graticule center .
c . Increase the RF
Attenuator setting in 10 dB steps
and note that the signal amplitude decreases 1 divison
each step .
d
.
Switch the RF Attenuator back to 10 dB, and
depress the LIN
display mode button .
e . Ensure that the baseline of the display is at the
bottom graticule line, and the 50 MHz signal is centered,
then adjust the VARIABLE
Gain control for a signal
amplitude of 6 .3 divisions .
f . Switch the RF Attenuator to 20 dB to add 10 dB of
attenuation, and note that the signal amplitude decreases

to approximately 2 divisions for a ratio change of 3 .16 (this
is equivalent to 10 dB in LIN mode) .
g . Return the RF Attenuator to 0 dB, the
VARIABLE
Gain control to CAL . The signal amplitude should return
to full screen and the REFERENCE LEVEL should indicate
-30 dBm .
6 . Adjust Contrast and Check Baseline Clipper
Operation
a . With the BASELINE CLIPPER control set midrange,
adjust the CONTRAST control for the desired ratio
between the clipped or subdued portion
and the restof the
display . Usually the contrast is adjusted so the clipped
baseline portion is just visible .
b . Adjust the BASELINE CLIPPER control so the
baseline is subdued . If there
is excessive noise it may be
desirable to clip noise level as well .
NOTE
The contrast ratio between theclippedportionofthe
display baseline and the rest of the display is
affected by the sweep rate, frequency span, resolu-
tion, and ambient light .
1 .
Signal Application
Fig . 2-5 . Volts-dBm-Watts conversion chart for
50
t2
Impedance .
Operating Instructions-71-13
USING THE ANALYZER
The
RF INput impedance to the 71-13 is 50 O
.
At high
frequencies, impedance mismatches between the RF
INput and the signal source can cause reflections in the
transmission line and degrade instrument performance .
Flatness, sensitivity, spurious response, etc ., are all
affected .
To reduce mismatch, use good quality 50
f2
coaxial cable to connect the signal source to the RF INput
and keep the cable as short as possible . Cable losses
become excessive above frequencies of 1 GHz .
Avoid applying high level signals (above -30 dBm) to
the 1st mixer of the 71-13 . High level signals overload the
mixer and
may produce spurious
signals
. A conversion
chart shown in Fig . 2-5 will aid in determining inputsignal
level, in dBm,pV, anduW, from a voltage
or
power
source .
The input maximum power level to the RFAttenuator
is 1 watt average or 200 watts peak . When the RF
input signals are riding on a do potential, use the do
block (Part No . 015-0221-00), to prevent the do from
reaching the 1st mixer . When the signal source is
75 n and you are using the75 to 50 0 minimum loss
attenuator, a do block is not required because one is
incorporated in
the attenuator
.
NORMAL OPERATING
RANGE
OdB
NOTE :

Volts RMS . . . multiply by
2 .8 for
peak-to-peak .
0 dBm 1 milliwatt
2-
9
~100pv 1Av 10'av 100uv 1mv ~10mv 100mv
OdBm -130d13m -120dBm -110d13m -100dBm -90dBm -80dBm -70dBm -60dBm -50dBm -40dBm
-30dBm -20dBm -10dBm
11W 11W 0 .001pw 0 .01pw 0 .1PW 1 .0pw 10pw 100PW 1 .0nW
10nW 1OOnW
1 .OgW 10JAW
100kW

2- 1 0
Operating Instructions-71-13
Spurious response, caused
by signal overload into the
1st mixer,
can be minimized if the signal
amplitude is kept
within the graticule limits .
A recommended procedure is to
adjust
the Gain selector for some baseline noise
on the
display, then increase
the RF Attenuator setting until the
strongest
signals are within the
graticule limits . If this does
not
bring these signals within limits, add
external
atten uato rs .
The 71-13 can be used
with a 75 f2 signal source by
using a 75 f2 to 50
f2 minimum loss attenuator . This
attenuator is available
as an optional accessory (refer to
the optional
accessories list in the catalog or
Accessory
page in the manual for ordering
information) . Sensitivity
and power levels are
often rated in dBm (dB with reference
to
1 mW regardless of impedance) . Sensitivity and power
levels
for 75 fl systems are usually rated in dBmV
(dB with
reference to 1 mV across 75
f2) . Fig . 2-6 is a circuit
diagram of a suitable
matching pad for this purpose .
The
conversion
from dBmV to dBm, and dBm
(75 0) to dBm
(50
0)
through the matching attenuators,
is shown in
Fig . 2-7 and described as follows
:
[1]

(dBmV, into 75 f2) - (dBm, at 50 f2 end)
=54 .46 dB
ordBmV=54 .5 dB+dBm .
Forexample :-30 dBm@50 ()
= 54 .5 dB + (-30
dBm) or + 24 .5 dBmV at the 75 f2 input .
[21 dBm @ 75 f1 = dBm @ 50 f1
+ 5 .72 dB . For
example : -30 dBm
@ 50 f2 + 5 .72 dB = 24 dBm @ 75 0 .
[3]
For some applications you may wish to
know the
relationship between dBm and
dBNV . For 50 f2 systems
dB,uV = (dBm) + 107 dB .
Fig . 2-6 . Circuit of a 75-0 to 50-f) matching
pad
(ac coupled) .
2 . Resolution,
Sensitivity, and Frequency Span
Resolution is
the ability of a spectrum analyzer to
discretely display adjacent signals
within a frequency
span . This resolution
ability is a function of analyzer
[31
dBMV
(5092)
+87
+67
+47
0
-107 -100
[21 [11
dBm
dBmV
(75 s2)

(75 s2)
M INE NOME
EMIMMOMME
No MEMNON,
MEEMERNME
EMEMOMMIN
MPAAVMMMIM
Mi
-104 .7
-80 -60 -40
-20
dBm (50 92)
Fig . 2-7 . Graph
to Illustrate relationship between
dBm, dBmV,
and dBMV
.
bandwidth, sweep speed, frequency
span, and incidental
FM . The frequency span and
sweep time are adjusted for
minimum bandwidth
to a cw signal . Theoretically, resolu-
tion and
resolution bandwidth become
synonymous at
very long sweep times .
Resolution
bandwidth is measured and
specified for
the 71-13 as the
bandwidth (separation)
at the 6 dB down
point on
the signal .
As the analyzer sweep rate
is increased, the signal
amplitude will decrease
and bandwidth will increase,
signifying that both
sensitivity and resolution have been
degraded .
The best resolution with no
video filter, for a given
frequency span and sweep
time is expressed as :
Bandwidth determines both noise
level and the resolu-
tion capability of the
analyzer . As the bandwidth
decreases, the
signal-to-noise level and, therefore,
sen-
sitivity
increases . Maximum sensitivity,
therefore, is ob-
tained at the higher resolution settings .
The frequency
span is symmetrical about
the center
frequency .
The frequency span to be used,
depends on the
application . Wide frequency spans are used
to monitor a
-Frequency Span
(in kHz)
R
o
_
Sweep Time (in ms)
O