Tektronix 7L5 User manual

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T ekt ronix, Inc.
P. O. Box 500
Beave rt on, Oregon 97077
07IH734-QO
TEKTRONI»
7L5
SPECTRUM
ANALYZER
OPERATORS
INSTRUCTION MANUAL
Serial Number
Scam bv Ou tso llr ce~Op t io n s - >

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WARRANTY
All TEKTRONIX Instruments are warranted against
defective materials and workmanship lor one year .
Any questions with respect to the warranty should
be taken up with your TEKTRONIX Field Engineeror
representative.
All requests for repairs and replacement parts
should be directed to the TEKTRONIX Field Ottice
or representative in you "r .-rea. This w II assure you
the tastest possible service. Please Include lhe
instrument Type Number or Part Number and SeriaL
Number with all requests for parts or service.
Speclflcalions and p Ice change privileges reserved.
Copyright @ 1976 by Tektronix , Inc ., Beaverton ,
Oregon . Printed in the United States of Am e rica . 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 ,
Inc .
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Section 1
Section 2
Section 3
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TABLE OF CONTENTS
General Information
Introduction
Description
Specification
Frequency Characteristics
Input Characteristics
Amplitude Characteristics
Sweep Characteristics
Output Connectors
Environmental Characteristics
Physical Characteristics
Accessories and
Options
Installation
Initial Inspection
Installation
Repackaging
Operating Instructions
Introduction
Functional Block Description
Front Panel Controls and Connectors
Calibrating the 7L5 to the Ostilloscope Mainframe
Operational Checkout (
Preliminary Preparation
Operational Check of Readout Characters
Dynamic Range Accuracy
Reference Level Accuracy
Input Buffer
Residual (Incidental) FM
Residual Response
Sensitivity
Check
Resolution Bandwidth Accuracy, Amplitude Deviation and Shape Factor
Using the Analyzer
Impedance
Matching
Signal Application
Edge Noise
Frequency Measurement Technique
Max Span Operation
Resolution and Resolution
Bandwidth
Digital Storage
Applications for Spectrum Analyzers
7L5 Operators
Page
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1734-1
Fig. 1-1. 7L5 Spectrum Analyzer,
7lS Operators
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Digitally signed by
ArtekMedia
DN:
cn=ArtekMedia,
o=ArtekMedia.com
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email=manuals@Ar
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c=US
Date: 2008.11.30
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Section 1-7L5 Operators
SPECIFICATION
..
Introduction
To effectively use the 7L5 Spectrum Analyzer, the
operation and capabilities
of the instrument must be
known.
This instruction manual covers general operating
information about the instrument. Service information,
such as
circuit description and calibration are contained
in the Service manual.
Description
The 7L5 is a 5 MHz spectrum analyzer with digital
storage. Frequency stability is within 5 Hz/hr and center
frequency (dot) can be read
with six digit accuracy
immediately after turn-on. Thereis no need to fine tunethe
display. Complex measurements and analysis can be
made
with relativeease. Built-in micro-processing circuits
decode control settings, process frequency and reference
level information, and optimize sweep time and resolution
for the selected frequency span.
The 7L5 with 80
dB or more of spurious free dynamic
range, provides the ability to measure wide relative
amplitudes.
Nanovolt sensitivity provides very low-level
signal and noise measurements.
The 7L5 display is fully calibrated in dBm, dBV, or
volts/div. The reference level can be accuratelyset to 1 dB
increments. A front panel input buffer control increases
front-end immunity to intermodulation distortion while
maintaining a constant reference level. To accommodate
a wide variety of impedance sources, the 7L5 uses quick
disconnect plug-in input impedance modules of 50 0,
750, 6000, 1 MO/28 pF and customized units to meet
special requirements.
Digital storage allows any 7000-Series mainframe, with
crt readout, to present clean, easy to photograph, dis-
plays. A smooth integrated display provides an accurate
analysis of most displays. Two complete displays can be
held in memory for comparison. Two modes select either
the conventional peak display or a digitally averaged
display.
ElECTR ICAl CHARACTER ISTICS
The following electrical characterstics apply when the
7L5
Spectrum Analyzer, in combination with a Plug-In
Module, are
normally installed in a 7000-Series os-
cilloscope and after a warm-up of ten minutes or more.
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Frequency Characteristics
Range
Input Frequency: 10 Hz through 5.0 MHz.
Dot Frequency: 0 Hz through 4999.75 kHz.
Accuracy
20°C to 30°C: ±(5 Hz + 2 X 10-6 of dot readout).
O°C to 50°C: ±(20 Hz + 10-5 of dot readout).
Drift
5 Hz/hour or less.
Residual (Incidental)
FM
50 Hz/div to 2 kHz/div: 1 Hz (p-p) or less.
5 kHz/div to 500 kHz/div: 40 Hz (p-p) or less.
Resolution
Bandwidth
Accuracy
30 kHz-30 Hz: Within 20% of selected resolution
(6 dB down).
10 Hz: Within 100 Hz ±20 Hz (70 dB down).
The COUPLED setting electronically selects
the best resolution bandwidth for each setting of
the FREQUENCY SPAN/DIV control.
Shape Factor
30
kHz-3 kHz: 5:1 or better (60:6 dB ratio).
1
kHz-10 Hz: 10:1 or better (60:6 dB ratio).
Amplitude Deviation
30
kHz-100 Hz: 0.5 dB or less.
30 kHz-10 Hz: 2.0 dB or less.
1-1

Specification-7L5 Operators
Input Characteristics
~
The application of a dc voltage to the INPUT of the
L1
or L2 Plug-In Modules may cause permanent
damage to the mixer circuit.
Input Impedance (Nominal):
L1 500
L2 750
L3 Selectable (500,6000, and 1 MO/28 pF).
Input Power (maximum input level for reference
levels of 0 dBm or greater):
L1 21 dBm or 2.5 V rms
L2
21 dBm or 3.07 V rms
L3
21 dBm-input terminated 500 or 6000;
100 V (peak ac + dc) input 1 MO/28 pF.
Input Power (maximum input level for reference
levels below 0 dBm):
L1 +10 dBm
L2 +10 dBm
L3 +10 dBm-input terminated 500 or 600 0,
and 100 V (peak ac + dc) with input of 1 MO/28 pF.
Amplitude Characteristics
NOTE
If digital storage is used, an additional quantization
error of 0.5% of full screen should be added to the
amplitude characteristics.
Residual Response
Internally generated spurious signals are -130 dBm
or less referred to the input (harmonics of the calibrator
are -125 dB) with L1 or L2 plug-in module and -143
dBV with the L3 plug-in module.
Sensitivity
The following tabulation of equivalent input noise
for each resolution bandwidth is measured with; the
INPUT BUFFER off, the VIDEO PEAK/AVG at max cw,
and the TIME/DIV set to 10 seconds.
1-2
Equivalent Input Noise
Resolution (equal to or better than)
Bandwidth
L1
L2 L3
10 Hz
-135 dBm
-135 dBm -148 dBV
30 Hz -133 dBm
-133 dBm -146 dBV
100 Hz
-130 dBm
-130 dBm -143 dBV
300 Hz
-125 dBm
-125 dBm -138 dBV
1 kHz
-120 dBm -120 dBm
-133 dBV
3 kHz
-115 dBm
-115 dBm -128 dBV
10 kHz
-110 dBm
-110 dBm -123 dBV
30 kHz
-105 dBm
-105 dBm -118 dBV
NOTE
Sensitivity is degraded an additional 8 dB when the
INPUT BUFFER is on; e.g., at 3 kHz, the equivalent
input noise would be -107 dBm instead of
-115 dBm. Noise level will increase by ap-
proximately 10 dB when operation is in video peak
mode.
Intermodulation Distortion
Intermodulation products from two on-screen
signals, within any frequency span are ?75 dB down
for third order products and at least 72 dB down for
second order products.
Second and third order intermodulation products
from two on-screen -53 dBV or less signals within any
frequency span are at least 80 dB down.
With the INPUT BUFFER switch on, the second and
third order intermodulation products, for any two on-
screen signals, within any frequency span, are at least
80
dB down.
Display Flatness
Peak to peak deviation, over any selected frequency
span: Quantization error must be added (see Note
under Amplitude Characteristics) if digital storage is
used.
L1 0.5
dB;
L2 0.5 dB;
L3 0.5 dB
Reference Level
Refers to top graticule line in Log mode. Calibrated
in 1 dB and 10 dB steps for the L1 and L2 modules and
1
dB/2 dB and 10 dB for L3 plug-in module.
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Range L1 L2 L3
Log
-128 dBm -128 dBm/ -128 dBm to
2 dB/Div to +21 dBm 139 dBV to
+21 dBm (500),
+21 dBm/
-139 dBm to
+10 dBV
+10dBm (6000),
-141 dBV to
+8 dBV (Hi Z)
Log
-70 dBm -70 dBm/ -70 dBm to
10 dB/Div
to +21 dBm
-81 dBV to +21 dBm (500),
+21 dBm/
-81 dBm to
+10 dBV
+10dBm (6000),
-83 dBV to
+8 dBV (Hi Z)
Incremental Accuracy
When calibrated at -40 dBV in Log mode.
L
1, L2 and L3: Within 0.2 dB/dB with cumulative
error of 0.25 dB/10 dB.
Lin
Mode Range: 20 nV/Divt0200 mV/Divwithin 5%
in 1-2-5 sequence.
NOTE
A >sign is displayed adjacent to the reference
level
readout when the reference level is not
calibrated due to an incompatible selection of
controls.
Display Dynamic Range/Accuracy
Log 10 dB/DIV Mode: Dynamic window is 80 dB.
Accuracy is within 0.05 dB/dB to 2 dB maximum.
Log 2 dB/DIV Mode: Dynamic window is 16 dB.
Accuracy is within 0.1 dB/dB to 1 dB maximum.
Sweep Characteristics
Frequency Span
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Provides calibrated frequency spans from 50 Hz/div
to max (500 kHz/div), within 4%, in 1-2-5 sequence.
Horizontal linearity is within 4% over the entire
10 div display.
A O-Hz/Div position is provided for time domain
operation.
Specification-7L5 Operators
Sweep Rate
Time per div is selectable from 10 s/Div to
0.1 ms/Div in 1-2-5 sequence. An AUTO position
permits automatic selection of optimu m time/d iv for the
selected resolution and span/div settings.
Sweep rate
accuracy is within 5% of the rate
selected.
Triggering
Provides two triggering sources, INT (internal) and
LINE, in
addition to a FREE-RUN position.
When INT is selected, ac coupled signal com-
ponents from the mainframe Trigger Source (left or
right vertical amplifiers) are used.
When
LINE is selected, ac coupled sample of
mainframe line voltage is used.
Three triggering modes are; NORM (normal), SGL
SWP/READY (single sweep), and MNL SWEEP
(manual sweep).
Trigger level is ~1.0 div of internal signal for both
NORM and SGL SWP modes over the approximate
frequency range of 30 Hz to 500 kHz.
Output Connectors
Video Out
Front-panel pin jack connector supplies the video
(vertical) output signal at an amplitude of 50 mV/div
±5% (about the crt vertical center) with source im-
pedance of 1 kO.
Horiz Out
A front-panel pin jack connectorsupplies horizontal
output signal (negative-going sawtooth that varies
from 0.0 V dc to approximately -6 V dc with a source
impedance of 5 kO.
Calibrator
Front panel BNC connector supplies a calibrated
500 kHz squarewave output signal (derived from the
analyzer's time base). Output amplitude is within
±0.15 dB of -40 dBV into impedance of the plug-in
rT'_ ..... III.o.
1-3
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Specification-7L5 Operators
ENVIRONMENTAL CHARACTERISTICS
The 7L5 Spectrum Analyzer will meet the foregoing
electrical characteristics within the environmental limits
of a 7000-Series oscilloscope. Complete details on en-
vironmental test procedures including failure criteria etc.,
can
be"obtained from a local Tektronix Field Office or
representative.
PHYSICAL CHARACTERISTICS
Net weight (instrument only): 8 pounds, 12 ounces.
ACCESSORIES AND OPTIONS
Standard Accessories
Graticule, Spectrum
Analyzer
Filter, light amber
Manual, Operating
Manual, Service
1-4
Tektronix Part No.
377-1159-02 (7000-Series)
378-0684-00
070-1734-00
070-2184-00
Optional Accessories
Plug-in Module,
50 ohm
Plug-in Module,
75 ohm
Plug-in Module
500,6000&
1 MO/28 pF
Probe (10X)
Attenuator, step,
50 ohm
Attenuator, step,
75 ohm
L1
L2
L3
P6105 (see L3 Manual)
2701
2703
OPTIONS
7L5 Option 21-(Log Display)
7L5 Option 25-(Tracking Generator)
7L5 Option 28-(Readout)
7L5 Option 30-(Option 21/25)
7L5
Option 31-(Option 21/28)
7L5
Option 32-(Option 25/28)
7L5
Option 33-(Options 21/25/28)
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Section 2-7L5 Operators
INSTALLATION
Initial Inspection
This instrument was inspected both mechanically and
electrically before shipment. It should be free of mars or
scratches and electrically meet or exceed all
specifications. Inspect the instrument for physical
damage and check the electrical performance by the
Operational Check procedure provided within these in-
structions. This procedure will verify that the instrument is
operating correctly and it will satisfy most receiving or
incoming inspection requirements. If all instrument
specifications are to be verified, refer to the Service
Instructions for the 7L5.
If there is physical damage or performance deficiency,
contact your local Tektronix Field Office or represen-
tative.
Installation
To install the7L5, align the upper and lower guide rails
with those in the receiving compartments of the main-
frame. Slide the instrument along the rails into the
mainframe. When the electrical
connectors at the rear of
the 7L5 make contact, apply firm, steady pressure to the
front panel until the rear connectors are engaged and the
front panel is approximately flush with the oscilloscope
front panel. To remove the 7L5, pull the release latch
labeled 7L5,
at the lower leftofthe front panel, and remove
the instrument.
REPACKAGING FOR SHIPMENT
If your Tektronix instrument is to be shipped to a
Tektronix Service Center for service or replacement,
attach a tag showing; owner (with address) and the name
of an individual, at your firm, that can be contacted.
Include complete instrument serial number and descrip-
tion of the service required.
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Save and re-use the container your instrument was
shipped in. If the
original packaging is not available or is
unfit for use, repackage as follows:
1. Obtain a shipping container of heavy corrugated
cardboard or wood with inside dimensions six inches or
greater than the instrument dimensions. This will allow
room for cushioning. Refer to Table 2-1 for carton test
strength requirements.
2. Wrap the instrument in heavy paper or polyethylene
sheeting to protect the instrument finish. Protect the front
panel with urethane f9am or cardboard strips.
3. Cushion the instrument on all sides by packing
dunnage or urethane foam between the carton and the
instrument,
allowing three inches on all sides.
4. Seal the shipping carton with shipping tape or an
industrial stapler.
TABLE 2-1
Gross
Weight (Ib)
Carton Test Strength (Ib)
0-10
10-30
30-120
120-140
140-160
200
275
375
500
600
If you have any questions, contact your local Tektronix
Field Office or representative.
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Section 3-7LS Operators
OPERATING INSTRUCTIONS
Introduction
This section contains; a simplified block diagram
description, function of the front panel controls and
connectors, an operational
check-out and familiarization
procedure, and a section devoted to the use and applica-
tion of the instrument. Service information is contained in
the Service Instruction manual.
FUNCTIONAL BLOCK DESCRIPTION
Functional Block Description
The 7L5 is a swept front end spectrum analyzer with
selectable front-end plug-in modules that permit the user
to obtain calibrated display for a number of different
impedances (i.e., 50 ohm, 600 ohm, etc.). The plug-in
module contains; selectable attenuation, the first mixer,
and an
input buffer selector that trades attenuation for IF
gain. Signal attenuation in the plug-in and gain of the IF
processing chain are controlled by a reference level logic
circuit in the 7L5 which provides calibrated settings in
1 dB or 10 dB steps overa range of approximately 146 dB
(depending on the plug-in module). A simplified block
diagram is shown in Fig. 3-1.
The input signal
to the 7L5 is mixed with thefrequency
of the main oscillator and the IF of 10.7 MHz is fed to and
amplified by the 10.7 MHz IF amplifier. Sincethe7L5 input
frequency range is 0 to 5 MHz, the main oscillator is tuned
and swept from 10.7
to 15.7 MHz. The frequency of the
main oscillator is controlled by two secondary (A and B)
oscillators that use a synthesizer technique to tune and
phase lock their frequencies. The sweep frequency
con-
trol circuit drives the oscillators according to thesettings
of front panel DOT FREQUENCY and FREQUENCY
SPAN/DIV controls.
@
The 10.7 MHz IF is processed through bandpass filters
and amplifiers and then mixed with the output from a
10.450oscillator, to down-convert the 10.7 MHztoan IF of
250 kHz. Gain of the 250 kHz amplifier is controlled bythe
reference level logic circuit which establishes the amount
of attenuation in the plug-in module and gain for the
250 kHz IF and Log amplifiers. The reference level is
selectable in 1 dB and 10 dB steps.
The 250 kHz IF signal
is processed throughthevariable
resolution filter circuits for bandwidth selections of 10 Hz
to 30 kHz. Thesignal is again amplified, detected, and the
video
is sent through amplifier circuits that provide the
10 dB/div, 2 dB/div, and linear gain characteristics.
The video signal is then fed to the display processing
circuits where the signal
is eitherstored and displayed,or,
if the storage mode
is not selected, the signal is passed
directly through the vertical output amplifier to the
mainframe circuit. If either or both the DISPLAY A or
DISPLAY B latches are enabled, the signal is converted to
digital data, stored in A or B memory,then converted back ~
to analog data and processed through the output
amplifiers to the mainframe. The vertical information is
digitized and stored at 512 horizontal address locations
across the screen. Therefore, the horizontal sweep infor-
mation is converted to digital data for storage, then
converted back to an analog signal for display. The
horizontal sweep ramp is processed the same as the
vertical signal. The vertical (video) information can be
averaged
or peak detected.
3·1

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FRONT PANEL CONTROLS AND
CONNECTORS
Pushing any front panel pushbutton switch activates a
bistable electronic circuit tochangeits output state. When
in the active state, the plastic
pushbutton is illuminated.
Pressing the pushbutton a second time changes the
output of the circuit to the inactivestate and extinguishes
the illuminated button.
Front panel
controls also include two special photo-
optic switch assemblies, the FREQUENCY SPAN/DIV-
RESOLUTION switch and the TIME/DIV switch. Deslgned
especially for the 7L5, each assembly is a
mechanical/photo-electric, digital switch, that provides a
TTL compatible five-bit binary output. The reliability of
these switches has been demonstrated and with normal
use theyshould last the life of the instrument. Dismantling
or field repair of these switches is discouraged since their
proper operation requires precision
alignment of their
internal components. If either switch assembly is damag-
ed
orsuspected of malfunction, it should be replaced as an
assembly.
The following describes the function of the front panel
selectors
for the7L5. A layout of the front panel is shown in
Fig. 3-2.
DOT FREQUENCY Changes the dot (marker) frequency
in coarse (10 kHz)
or fine (250 Hz)
steps over the
input frequency range
of 0 Hz to 5 MHz. The frequency of
the dot marker is displayed on the crt
readout in the upper right set of
characters. Dot frequency will not
extend beyond the 7L5 frequency
range, even
if the control is rotated.
When
power is applied, dot frequen-
cy starts at 0.000.
FINE
TUNING
@
Selectscoarse or fine incrementation
for the DOT FREQUENCY control.
When the FINE TUNING switch is
activated (illuminated), each
rotational click of the DOT FRE-
QUENCY
control changes the dot
frequency in increments of 250 Hz.
When the FINE
TUNING switch is
inactive (extinguished), each
rotational click of the DOT FRE-
QUENCY
control changes the dot
frequency in increments of 10 kHz.
Operating Instructlons-7LSOperators
DOT MKR
REFERENCE
LEVEL
VAR
INPUT BUFFER
Used
to horizontally position the fre-
quency dot.Thedisplayed frequency
readout characters enumerate the
actual frequency ofthe dot.When the
DOT MKR control is in its detent
position
(fully ccw), the frequency
dot and the selected frequency are
on the vertical center line
of the
graticule. The 7L5 can beoperated in
a start sweep
mode when the fre-
quency dot is positioned to the left
vertical graticule line. The
DOT MKR
control is disabled when the FRE-
QUENCY SPAN/DIV switch is
at
MAX.
Sets the full screen signal amplitude
level (dBm, dBV) required at the
INPUT to the plug-in module. This
level is relevant to the input im-
pedance
of the plug-in module.
Reference level is associated to the
top graticule line of the display area
and signal level is relative
to this
reference. The reference level range
depends on the plug-in module,
however, in the 2 dB/Div mode it
covers 149 dB, in the 10 dB/Div
mode the range is 90 dB and in the
Lin mode
20 nV/div to 200 mV/div.
The
control has two speeds or step-
ping increments; pulled out, each
increment is 10 dB, pushed in each
increment is 1 dB or in some cases
(dependent on the plug-in
module)~
2 dB.
The VAR (variable)
control provides
8
dB or more gain adjustment
between each calibrated reference
level step. A<symbol is displayed on
the crt, preceding the reference level
readout, whenever the reference
level is not calibrated (VAR is not in
its detent position).
The active (illuminated) state
of this
pushbutton switch inserts 8
dB of
signal attenuation at the input of the
first mixer and adds 8
dB of vertical
gain (after the variable resolution
filters). When used,
it reduces inter-
modulation distortion caused byex-
cessive input signal amplitude.
Because of its increased gain, the
noise figure is increased 8
dB when
this switch is activated.
3-3

Operating Instructlons-7l5 Operators
Repositions frequency dot
b<ltween grltic:u" c:ctnter
and left edg •.
Illumin ates wherHtwr the
RESOLUTION , TIME / OIV
and FREOUENCY SPAN/
OIV controll . r. lilt to
mutually incompootible
positions .
Attenuates input signal.
Can r. duc:e 1M di.tortion
caused by .xc:ctuive input
a mplitud e.
Veriab" r.f .. enQl
adjustment. 0..8 dB.
Two position r.ferenc:e
"veladjuJ1. Used to lilt
the •• letive a mplitud a of
input signal with r.5PKI
to referenQl ..... 1.
Calibrator output sigrHtt.
500 kHz "'lI1 @ -40dBV .
3-4
7L5 m.infum ...... s.
I.IIIc:h .
Tunes the dot frlquency
o .. r the frlquency rang e.
. •.
,. ... .
Ii
Selel;:ts coa ... ( 10 kHd or
firHt (250 Hzl incrementation
for f'lquency COntrol.
Vert;Cllamplifi. mode
lllleet pushbuttons .
Trigg
... Mod. lII"ct push -
~~t~~~~ __ ~~~~~~ ____ ;b; " ~'.';O;,"~~; .. s..;;;: Seetion 2 for
output signal to sla .. an
.xterna l d..... c:e (Z 5!!: 5 knl .
T;i",. ",",.~ llllect push -
buttons-See Section 2 for
' xPlanation .
Compensates for lIIIin
diff.enOlll between mIIin-
fr.me oscilloscopel .
V.<oii;"
0"',,", Ilgnal for
.xterne l d•..,icelluc:h as r. -
corder (Z £'!! 1 kn l.
Fig. 3-2A. 7L5 fronl panel controls end connectors.
@
•

@
Used to blank Or elip t....
signal
baseline when digital
storage il off . With Rorage
on, sets th e eursor leYIIlat
whieh the di s play is aver ·
IIi8d ( below eurlO.) or peak
dateoctad ( above eurlOrI.
RF input eonnector , P/O
plug';n mOd"' .. ~
Inhibits t .... " A" memory
from further update .
Activates digitalnorage and
selects the "A" or ''8'' por ·
tions of memory for di lplay.
•
• •
Operating Instructlons-7LS Operators
Permits monitoring of m ... ·
imum signal exe urs io ns over
an indefinite time pvriod.
TlM V OIY
Selects the frequeney span
per division, 50 Hz..sOO kHz.
Inelude s 0 Hz position for
domain analysis.
Select s the relOlution band·
width. 30 kHz to 10 Hz.
i k; i
Equal am plitude Cil l ibration - -';;;~~ L:: ~:= ~:~~:~Ai~:j::~~~~~.!~~~!! J
adjustment for 10 dB /d iY
and 2 dB / diY l ag a mplifier s.
•
Plug·in m,.d,," " •• , ~ Lateh.
Seleet:s
the ref &r enee level
scale fa
eto r dBm or dBV.
"!'.<U "_""',".l ~ -
10s.
Calibrates frequency
span p&r division. Used to
eompen sate f or ma i nframe
deflection sensitivity
diff&renees.
1734-4
Fig. 3- 28 . 7lS - l1 plug -In Ironl panel contrOl and connectors.
3·5
Scans br Ollisollrce·OptiolfS =>

Operating Instructions-7L5Operators
LOG 10 dB/DIV
LOG 2 dB/DIV
LIN
FREQUENCY
SPAN/DIV
RESOLUTION
TIME/DIV
UNCAL
3-6
The illuminated condition of this
pushbutton selects alogarithmicdis-
play
of 10 dB/div with a dynamic
range
of 80 dB.
The illuminated
condition of this
pushbutton selects alogarithmicdis-
play of 2 dB/div with a dynamic
range
of 16 dB.
The illuminated
condition of this
pushbutton selects a linear display.
Signal amplitude is a linear function
of input level.
TRIGGERING
Selects frequency spans from
_______ ~_~ __
50 Hz/div to 500 kHz/div (MAX posi-
tion). A 0 Hz position provides time
domain display with a bandpass
dependent on the setting
of the
RESOLUTION selector. In the 0 Hz
position the frequency
dot is not
displayed and when in the MAXposi-
tion the frequency dot position is
controlled by the DOT FREQUENCY
control.
Selects resolution bandwidths of
10 Hz to 30 kHz in a 1-3sequence. A
COUPLED position electronically
selects the best compatible resolu-
tion bandwidth setting for the FRE-
QUENCY SPAN/DIV selection.
Selects the analyzer's sweep rate.
Sweep rates are 10 s/div to
0.1 ms/div in a 5-2-1 sequence. An
AUTO position electronically
programs sweep rate so the display
remains calibrated for the selected
frequency span and resolution
bandwidth settings.
When the display
is uncalibrated
because the FREQUENCY
SPAN/DIV, RESOLUTION, and
TIME/DIV switch settings are incom-
patible, this indicator lights and a>
symbol is displayed on the crt as a
prefix to the reference level readout
characters.
LEVELISLOPE-
MNLSWP
DIGITAL
STORAGE
Two trigger sources (Line and Inter-
nal) plus a Free Run mode can be
selected. In the Free Run mode
(FREE RUN button activated) the
sweep free runs and will
not sync
with any
trigger signal. When the
LINE pushbutton is activated
(illuminated) the sweep is triggered
by the line voltage
to the mainframe.
The INT pushbutton selects ac
coupled signal components from the
mainframe Trigger Source (left or
right vertical).
Three trigger modes are provided:
NORM (normal), SGL SWP/READY
(single sweep/ready) and MNL
SWEEP (manually controlled
sweep). When the NORM button is
activated, thesweep is triggered from
the source selected; or, if the trigger
is not present, the sweep
automatically runs in about 10-
second intervals to provide a
baseline display. When the SGL
SWP/READY button is activated, the
sweep runs with the next trigger or in
about 10 seconds if trigger is not
present. In time domain operation
(FREQ SPAN/DIV at 0 Hz) pushing
the button activates the sweep ready
state.
The button lights to indicate
the
trigger circuit is armed and ready.
The sweep will run with the arrival
of
a trigger. The button remains il-
luminated until the sweep has com~~
pleted its run. This provides a ready -
indication
of the sweep state when
photographing a display.
A dual function control. As a level
slope/control, it adjusts the level
of
the trigger threshold on either a
positive
or negative slope. As a
manual sweep control, it positions
the
crt beam anywhere along the X-
axis. Maximum ccw corresponds toa
beam location at the left graticule
edge.
SAVE A: Activating the SAVE A
pushbutton dedicates one half
of the
digital storage memory to preserve
the binary equivalent
of the existing
waveform amplitude at 256 X-axis
locations. The A memory is inhibited
from further update until SAVE A is
deactivated (extinguished).
@
..J
-,
J
J
]

SWP CAL
LOG CAL
@
DISPLAY AlB: When DISPLAY A or
oISPLAY B is selected, the cor-
responding pushbutton switch is il-
luminated and the contents of
memory A or memory B is displayed.
With SAVE A off, all memory
locations are displayed contiguous-
ly. With SAVE A on, DISPLAY A and
DISPLAY B are selected. The con-
tents of both memories are interlaced
and displayed.
PEAK AVERAGE/BASELINE
CLIPPER: A dual function control.
When digital storage is off, this con-
trol operates as a conventional
baseline clipper, i.e., as the control is
rotated ccw, more of the vertical
display is progressively blanked or
clipped over the last 1/3 turn of the
control. When digital storage is on,
the PEAK AVERAGE control sets the
level
at which the vertical display is
either peak detected or digitally
averaged. Video signals above the
level set
by the PEAK AVERAGE
control (and denoted by a horizontal
cursor) are peak detected and stored.
Video signals below the level set by
the PEAK AVERAGE control are
digitally averaged and stored.
MAX HOLD: Enables the digital
storage memory to store the max-
imum signal levels within the period
the circuit is active (button il-
luminated). This maximum Signal
can then be saved and compared
with future signals for drift or
amplitude variations.
Adjusted during the operational
check to calibrate the sweep. This
adjustment compensates for
differences in deflection sensitivity
between mainframe oscilloscopes.
The SWP CAL control should be
adjusted or checked for proper set-
ting each time the 7L5 is installed in
an
oscilloscope.
Adjusted during the operational
check to calibrate the 2 dB/div and
the 10 dB/div displays. This adjust-
ment is used to compensate for
differences in vertical gain between
mainframe oscilloscopes. The LOG
CAL control should be adjusted or
checked for proper setting each time
the 7L5 is installed in an os-
cilloscope.
Operating Instructions-7LSOperators
AMPL CAL (L1
Plug-In Module)
HORIZ POS
VERT POS
dBm/dBV
The AMPL CAL control is adjusted
during the initial calibration to
calibrate the full screen reference
level.
This control is used to compen-
sate for gain differences in the RF
and IF portions of the instrument.
The AMPL CAL control should be
adjusted or Checked for proper set-
ting each time a plug-in module is
installed in the 7L5.
Positions the display or baseline on
the crt X-axis.
Positions the display or baseline on
the crt Y-axis.
Located on the plug-in module front
panel, the dBm/dBV control selects
the reference level scale factor;
decibels with respect to one milliwatt
or decibels with respect to one volt.
Calibrating the 7LS to the Oscilloscope Mainframe
1. Install or verify the presence of a plug-in module
(see Optional Accessories, Section 1).
2. Select oscilloscope Vertical Mode, Horizontal Mode
and Trigger Source (Right or Left) corresponding wit~
plug-in compartments occupied by the spectrum·"
analyzer. Turn on the mainframe power and allow a 10
minute warm-up period.
3. Set the front panel controls as follows:
DOT MKR max
ccw (detent position)
FREQUENCY
SPAN/DIV
MAX (500 kHz)
RESOLUTION
COUPLED
VAR max
ccw (detent position)
BASELINE
CLIPPER max cw
LOG 10 dB/DIV
on
REFERENCE LEVEL
-40 dBV
INPUT BUFFER
off
FREE RUN on
NORM on
SAVE A off
MAX HOLD
off
dBm/dBV
dBV (plug-in module
switch)
TIME/DIV
AUTO
3-7
Scam by OlllSou,ce-Options ->

Operating Instructions-7L5 Operators
4. Connect the CALIBRATOR signal to the INPUT
connector on the plug-in module with a short length of
coaxial cable. Adjust the SWP CAL and the HORIZ
POSITION controls to align the second and tenth vertical
signals
with the second and tenth vertical graticule lines
counting from the left edge.
5. Set the FREQUENCY SPAN/DIV to 2 kHz, Display
Mode 2 dB/div, and DISPLAY Aand Bon. Adjustthe VERT
POSITION control to place the display baseline on the
bottom horizontal graticule line.
6. Set RESOLUTION control to 3 kHz and DOT FRE-
QUENCY to 500.00 kHz.
7. Select the LOG 10 dB/DIV pushbutton and adjust
the LOG CAL control for a full screen (8 division) display.
8. Select the LOG 2 dB/D IV pushbutton and adjust the
AMPL CAL (on plug-in module) for a full screen display.
9. Repeat steps 7 and 8 until the displayed waveforms
are 8vertical divisions in both log amplifier settings. (Refer
to Fig. 3-3, Log Amplifier Calibration Composite
Waveform.) If desired, check linearity of the 10 dB/div
display by increasing the REFERENCE LEVEL in 10 dB
steps. Adjust LOG CAL slightly to correct any non-
linearity.
'11
~
5 ace
HZ
1 I \
L \
I ,
} \
/ \
. ~
--'l •. :>. J ..L? b.. .
r\.
..""
".
i1W
l734-5
Fig. 3-3. Log amplifier calibration composite waveform.
3-8
OPERATIONAL CHECKOUT
Introduction
This is an operational checkout procedure intended to
satisfy
most customer's recelvmg inspection re-
quirements and to provide instrument familiarization for
the new user. We recommend using this checkout as part
of the users routine maintenance program and a
preliminary check before performing the Performance
Check portion of the Service Instruction manual.
The front panel CALIBRATOR output is an accurate
signal source and is used in the following procedures to
verify operational status of the instrument. Calibnitor
frequency accuracy may be verified by applying it to an
accurate digital counter.
Some procedures require a step attenuator and two
short lengths of coaxial cable. To verify the absolute
reference level specifications, the attenuator accuracy
must be calibrated or verified at some specific frequency,
to within 0.03 dB/dB with a cumulative error not to exceed
0.1 dB for any change up to 10 dB. Incremental accuracy
can be verified and a good indication of the absolute
reference level accuracy can be obtained by using two
Tektronix Step Attenuators, such as the 2701 (see Op-
tional Accessories, Section 1). These attenuators provide
a good indication of operation even though their accuracy
specifications are not within the limits described.
1_ Preliminary Preparation
Preset the front panel controls and selectors as
described under Calibrating the 7L5 to the Oscilloscope
Mainframe and perform the calibration procedure as
previously described.
2_ Operational Check of Readout Characters
With the 7L5 installed and operating in a 7000-Series
mainframe, perform the following steps to check the
readout operation.
Dot Frequency Readout
a. Verify that the dot frequency readout is 0.00 kHz
after initial turn-on. (Readout characters for the dot
frequency are located near the top edge of the crt and can
be
identified by the suffix characters kHz).
b.
With the FINE TUNING pushbutton not illuminated
(inactive), verify that the DOT FREQUENCY control
changes the value of the readout characters in 10kHz
increments.
@
Scans by OlllSoll,ce-Opt;o1lS =>

l_~
c. Rotating DOT FREQUENCY control cw should
increasethe readoutand ccw rotation should decreasethe
readout.
d. Activate the FINE
TUNING pushbutton and verify
that the DOT FREQUENCY control changes the value of
the readout characters in 250 Hz increments.
e. Verify that continuous cw rotation of the DOT
FREQUENCY control causes no change of the readout
characters
after an indicated 4999.75 kHz.
NOTE
Following a change of the DOT FREQUENCY
control, the first click in the opposite direction will
have no effect.
Reference Leyel Readout (L1
Plug-In Module)
f. Select the LOG 2 dB/DIV mode and set the
dBm/dBV switch (on the plug-in module) to dBm. Verify
that the indicated value of the reference level changes by
13 dB (e.g., -40 dBV = -27 dBm). Reference level
readout characters are located nearthe top edge of the crt
and can be identified by the suffix characters dBm or dBV.
g. With the UNCAL light off, rotate the VAR (variable)
control and verify thata< symbol (notcalibrated) prefixes
the reference level readout. Rotate the VAR
control to its
maximum ccw (detent) position and verify that the <
symbol is no longer displayed.
h. Pull the REFERENCE LEVEL control out to its
coarse position and verify
that the value of the reference
level readout changes in 10 dB steps. Push the
REFERENCE LEVEL
control in to its fine position and
verify that the value of the reference level readoutchanges
in 1
dB steps.
i. Verify, that rotation of the REFERENCE LEVEL
control beyond the reference level limits of; -128 dBm
(-141 dBV), in the 1 dB/step position, or; -70 dBm
(-83 dBV) in the 10 dB/step position-for the one
extreme-and +21 dBm (8 dBV) for the other extreme
remains constant. (These extremesare
applicable on Iy for
50 0 plug-in modules.)
j. With the REFERENCE LEVEL control at max ccw
position, select the LIN mode and verify that the readout
changes to
200 mY.
@
GY
Operating Instructlons-7L5 Operators
k. Rotate the REFERENCE LEVEL cw and verify that
the readout changes
from mV to Jl.V to nV in a 2-1-5
sequence. Verify that continuous cw rotation of the
REFERENCE LEVEL
control causes no change of the
corresponding readout characters beyond 20 nV.
Time/Diy Readout
I. Set the FREQUECNY SPAN/DIV switch to O. Rotate
the
TIME/DIV control to each of its positions and verify
that its front panel designations correspond to the crt
readout characters. (Readout characters for the sweep
time
per division are located nearthe bottom right edge of
the crt and can be identified by the suffix character S
when the FREQUENCY SPAN/DIV is set to 0.)
Frequency Span/Diy Readout
m. Set
TIME/DIV control to AUTO and the
RESOLUTION control to COUPLED. Rotate the FRE-
QUENCY
SPAN/DIV control to each of its positions and
verify that the readout characters correspond
with the
front panel designations and change in accordance with
the readout listed in Table 3-1. (Readout characters
for
frequency span per division setting occupy the same crt
position as the time per division readout characters. They
are located nearthe
bottom edge of the crt and except for
the 0 span setting, can be identified by the suffix
characters Hz.)
TABLE 3-1
FREQUENCY SPAN/DIV
FREQUENCY SPAN/DIV
control settings readout
0 10 ms
50 (Hz)
50 Hz
.1 kHz
100 Hz
.2 kHz
200 Hz
.5 kHz
500 Hz
1 kHz 1 kHz
2 kHz 2 kHz
5 kHz 5 kHz
10 kHz
10 kHz
20 kHz 20 kHz
50 kHz
50 kHz
.1 MHz
100 kHz
.2 MHz
200 kHz
MAX
500 kHz
Resolution Readout
n. Rotate the RESOLUTION
control to each of its
positions and verify
that the readout characters corres-
pond with the front panel designations. (Readout
characters
for the resolution function are located nearthe
bottom edge of the crt and can be identified by the suffix
characters Hz.)
3-9
~

Operating Instructions-7LS Operators
o. With the RESOLUTION control in the COUPLED
position, rotate the FREQUENCY SPAN/DIV to each of its
positions and verify that the RESOLUTION readout
characters change in accord with Table 3-2.
TABLE 3-2
FREQUENCY SPAN/DIV
control settings
MAX (500 kHz)
200 kHz
100 kHz
50 kHz
20 kHz
10 kHz
5 kHz
2
kHz
1 kHz
.5 kHz
.2 kHz
.1 kHz
50 (Hz)
o
RESOLUTION
readout
30 kHz
30 kHz
30 kHz
10 kHz
3 kHz
3 kHz
1 kHz
300 Hz
300 Hz
100 Hz
30 Hz
30 Hz
10 Hz
30 kHz
Vertical Amplifier Mode Readout
p. Select the 10 dB/DIV pushbutton switch and verify
that the readout characters for the vertical amplifier mode
indicate 10 dB/. Readout characters for the vertical
amplifier mode are located near the lower edge of the crt
and for the log positions, can be identified by the suffix
symbol/.
q. Select the 2 dB/DIV mode and verify that the
readout characters indicate 2 dB/.
r. Push the LIN pushbutton and verify an absense of
readout characters for vertical amplifier mode.
Uncalibrated Readout
s. Set the RESOLUTION control to COUPLED and the
FREQUENCY SPAN/DIV control to MAX. Rotate the
TIME/DIV cw until the UNCAL light is illuminated. Verify
that a > symbol prefixes the referenced level readout
characters. Rotate the TIME/DIV ccw until the UNCAL
light is extinguished. Verify that the> symbol is no longer
displayed.
3-10
UE,th
3. Dynamic RJ.I' .. '1 I ,
NOTE
The full dynamic range of the Log 10 dB/div and the
Log 2 dB/div is not measured in the following
paragraphs. If the log amplifiers include a negative
error, full range verification would require signal
level measurement below the display baseline. Since
this is not possible, the following steps verify 78 of
the 80 dB range and 15 dB of the 16 dB range for the
two log amplifier selections.
LOG 10 dB/DIV (Dynamic window is 80 dB, accuracy is
±0.05 dB/dB to 2 dB maximum)
a. Set the 7L5 controls as follows:
DOT FREQUENCY 500.00 kHz
RESOLUTION COUPLED
FREQUENCY SPAN/DIV 0.1 kHz
TIME/DIV AUTO
REFERENCE LEVEL -40 dBV
dBm/dBV (L1 plug-in) dBV
b. Apply the CALIBRATOR signal through external
attenuator(s), such as Tektronix, 2701 (for 500)-see
Optional Accessories in Section 1-to the INPUTconnec-
tor. Select the LOG 10 dB/DIV pushbutton.
c. Increase external attenuation in 10 dB steps to
70 dB and verify that each step decreases the displayed
signal level 10 dB ±0.5 dB.
d. Increase external attenuation by 8 dB (for a total of
78 dB) and verify that the total overall decrease in signal
amplitude is 78 dB ±2.0 dB.
LOG 2 dB/DIV (Dynamic window is 16 dB, accuracy is
±0.01 dB/dB to ±1 dB maximum)
e. Set the external attenuators to 0 dB. Set the FRE-
QUENCY SPAN/DIV to 50 Hz, RESOLUTION to 30 Hz
and
select the 2 dB/DIV pushbutton.
f. Add 15 dB attenuation, with the external 1 dB step
attenuator, in 2 dB and 1 dB increments. Verify that the
signal level change, is within 0.1 dB/dB of added attenua-
tion to a maximum of 1.0 dB deviation over the 15 dB
range.
LIN Linearity
g. Select the LIN pushbutton and adjust the
REFERENCE LEVEL
control for a crt readout of 500 I1V/
(per division).
@