Tektronix 7L12 User manual

L~~

I N ST RU CTIO N
ΜΑΝ U ΑΙ
070-1298-01
7
L 12
SPECTRUM
A N A L Y Z
ER
Serial N umber

-

'
Te k
tronix,
Inc .
t Ρ .
Ο . Box 500

Ao-

B eaverton, Orego n 97005

+

Ph one : 644-0161 t Ca b les : Te k tronix
772

W
ARRANTY
All TEKTRONIX instruments
are warrante d against
defective materials an d
workmanship for one year . Any
q uestions
with res p
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 dp rice change privileges reserv
Copyright @ 1972, new material 1973, b y Tektronix,
Inc ., Beaverton, Oregon . Printed in the United States of
America . All rights reser v ed . Contents of this p ublication
may not b e repro duced in any form without permission of
Te k tronix, Inca
U .S .A . and foreign T EK TR O N IX prod ucts covered b y
U
.S
.
a nd foreign p ate n ts and /or p atents p ending
.
TEKTRONIX is α registered trademark of
Tektronix, In

TA
BLE
O F CO
N TEN
TS
SE CTIO N
1

Sp ecifications

P age
Introduction
E lectrical C ha r acteristics

1-1
S
E CTIO N 2

O
p erating
I n st ru ctio n s
Introduction

2-1
Fun ction
of t he Fr on t P anel Controls and Connectors

2-1
Ge
n
eral O p erati ng I n fo r mation

2-6
P reliminary
F ro nt Pan el Setu p an d Cali b ration

2-6
P
roce
du r e
to M atc h t he71_12 to t he Oscillosco p e
Cali b rati ng t
he Swee
p
2-6
C h
ec
k and
Ad ju st L og-Am
p
Cali b ratio n 2-8
C h ec k L in M odeand
10 d B /Div O p eration

2-9
A dj ust Contrast an d C
h
ec
k B aseline Cli
pp er
O pe r atio n 2-9
U si ng t heAnalyzer
Signal Ap p lication

2-9
R esolution, Se n sitivity an d Fr e q uency S p a n
2-11
Gain Desensitizatio n N ea r 0 Hz

2-11
Selecti ng
Sweep R ate

2-11
Trigge r ing t he Dis p lay

2-12
How to Swee p t he Disp lay U sing
an E
xternal
Swee p Sou r ce

2-13
E xternal Trigge r e d Op e r ation U sing α V e r tical Am p lifie r
Plug-in U nit as t h e Source

2-14
U sing t he Cal Out Sig n al R eference fo r Accurate F r e qu ency
an d Ap p licatio n s

2-15
Applications

2-15
S E CTIO N 3

P erfo r mance C h
ec
k
Pr eliminary P re p aration

3-1
C hec k 10 dB /DI V
a nd L I
N M
od e Cali b ratio n s

3-1
C hec k t he F re q
ue n cy R ea d ou t Accuracy

3-1
C hec k Gain
Selecto
r
Accuracy an d V a r ia b le R a n ge

3-2
C h ec k O p eration of the V i deo F
ilte r 3-2
C h ec k Sen sitivity

3-2
C h ec kF or S p ur io us Sig n als ( R esi d
ual
R
esponse)

3-4
C h ec k R esol u tion Bandwi
d
t hs
and S hape F actor

3-5
C h ec k I n
ci
d ental FM

3-6
P e r fo r ma n
ce
C heck
s R equ i r i ng Test Equ i p me n t
E q u i p ment R e q
uire d 3-7
C h ec k Cali b rato r F re q
uency

3-8
C h ec k Cali brator O u t pu t

3-8
C h ec k RF Atte n uato ι Accuracy

3-9
C h ec k Dis p lay F lat n ess

3-9
Ch
ec
k Intermodu
latio n Disto r tio n 3-10
Ch ec k V ideo P rocesso r Ope r atio n
3-10
Ch ec k Time/Div Acc ur acy a nd V a r ia b le R ange

3-11
C h ec k Trigge r i ng Ope r ation and Sen sitivity

3-12
C h eck t h e H orizo n tal I npu t V oltage R equ irement

3-13
C h ec k Fre qSp an Accuracy an d L inea r ity

3-13

TABLE OF CONTENTS
(cont)
SECTION4

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 300kHz
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
SECTION5

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)
SECTION6

Maintenance Information

Page
Preventive Maintenance
Cleaning

6-1
Lubrication

6-1
Transistor and IC Checks

6-1
Performance Checksand 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
SECTION9

Mechanical Parts List and Illustrations
(Exploded View)

9-1

Fig . 1-1 . 71-12 Spectrum Analyzer

SPE CI F ICATIO N
S
Section 1-7 L
12
Introduction

Sectio
n 9, Mec h anical P arts L ist, Exp
lode d d rawi n gs an d
Th is manual contai n s
information re q uired to operate,
Accessories : Pr ovi d es informatio n
necessary to or d er re-
test, cali b rate, a n d service t h e 71_12
Spectrum Analyzer .

p
lacea b le p arts . P art L ist is cross-reference
d to t h e Electrical
T
h e manual is d ivi d e d into ten ma j or sections
;

P
arts L ist .
E
xp lo ded drawi n g s h ows
se quence of assemb ly
an d
i
d entifie d assemb lies .
Section
1, General Information an d Specifications
.
Section 2, O p eration I n structions : Information relative
to installing
and o p erating t h e i n stru m en t .
Sectio n
10, Manual C h anges an d Correctio n s
:
P
rovi d es
h istory
and
upd
ating i n formatio n for t h e
ma
n
ual in t he
form of inserts
. As t
he
ma n ual is u pd ate d
t
h
ese inse r ts are
incor p orate d
into t
he
man u al text and d iagrams .
Section 3, P erformance
C
h ec
k : P rovi d es α com p lete
p roce du re to ch ec k
operatio n al performance for an in-

Description
co m ing acce p tance c h ec k ,
o
r
any ad d itional performance
c h ec k s t h at re q uire test e q ui p
ment to verify instrument

The 7 L 12 Spectr u m Analyzer is
α d ual-wi d t h p l u g-i n
specificatio n s .

u nit,
for t h e 7000-Series Oscilloscopes
. Wh e n use dwith any
of t h
ese oscilloscopes, it d is p lays
α s pectrum of signal
e n ergy
wit
h
in any freque ncy s p an to
1 .8 GH z . T h e unit
con tai n s h orizo
n tal sweep a nd timing
circuits, fo r fre-
Section 4, Calibration P roce
d ure : Descri b es test eq ui p -

quency an d time
d omain displays, a n d also
means b y w h ic h
ment set u p anda d j ustment p
roce d ures re q uired to align t h e

an exter n
al
sweep
source can be a pp lie d to slave
t
he
71_12
instru m ents inter n al a d ju stmen ts .

to exter n al d evices,
suc
h
as α r ecor d er .
Section
5, Circuit Description : P rovi d es b asic
and
general circuit
analysis th at may b e useful w hen servicing or
o p erating
t
he
instr
u
me n t .
Section 6, Mainte n ance I n
structions : Descri b es routine
andco r rective maintenance p roce d ures
wit h d etaile d in-
structions for replacing assemblies, su b
-assem b lies, and
in d ivi d ual com p onents . An exp lo ded
d
rawing
is
p
art of
section 9 . Trou b le-s h ooting procedu res plus
general infor-
mation t h at may ai d in servici n g t h e instr u ments
are also
p
rovide d .
Section 7, E
lectrical
P
arts L ist : P rovi d es
information

F re q uency
Sp an
necessary
to or d
er
replacea b le p arts and assemblies .
S PE CI F
ICATIO N S
ELE CT R ICA L C H A R
ACT ER ISTICS
T h e
following ch aracteristics a n d
features of t he 71_12
Spectrum A
n alyzer are applica b le after
α warm
up
pe r io d of
30
minutes
or more .
Center F
requency Operating R angean
d Acc u racy
From
0 .1
MH z
to 1 .8 GH z . R ea dout accuracy
is with in
± (10 MH z + 1°/
ο
of t
he
dial rea d o u t) .
Cali
b rate d steps, i n 1-2-5 sequence, from
500
Ητ
/Div to
100 MH z/Div .
Accuracy is wit h in 5% of t h es
pan selecte d
an d li n
earity is wit h in 5%, over t h e center 8d
ivisions of α
Section 8 . Diagrams : P rovi d es functional
b loc k d iag r am

10 division d
is p lay .
and d etaile d circuit sc h ematics . P ictoral
layout d rawings,
w h ic h
s
h
ow assembly, su b -assem b ly, an d com p
onent loca
tio n s are
locate d ad j ace n t to t h e d iagram (us u ally
on t he

Two a d ditio n al p
ositio
n
s MAX SP A N an d0 provi
d
e
bac k
of t
h
e p rece d ing diagram

p age)
. W
aveforms and
ap p roximately 1 .8 GH z
(180
MH
z/Div) of span, or fixed
voltage
d ata, for trou b les h ooti ng or circuit analysis,
ar e also

fre
q uency operation, for time
domain d is p lay . Sp an is
provi
d e d a dj acent to or on t he d iagram .

con ti n uo u sly varia b le between steps .

Specifications-71_12
Dis p lay F latness

R
esolution
±1 .5 dB over any selecte d frequency
s pan , with r es p ect

F
ive resolutio n b and wi d
t
h
selections from
300 Hz to
to t he d is p lay level at 50 MH z .

3 MH z,
in d eca d e steps, are p
rovide d . B an dwid t h accuracy,
at
t
h
e 6 d Bd ow n level, is
wit h in 20% of t h e resolution
selecte
d . S hap e factor over t he
60 d
B
to 6 d B level is 4
:1 or
Dis p lay M o d es

b etter
(see
F
ig . 3-4) . Signal level
ch a n ge over t he five
L OG 10 d B /DI V : P rovi d es α cali b
rate d 70 dB d ynamic

band wi d
t
h
s is less t h an 0 .5 dB .
range .

Accuracy

wit h i n 1 dB /10 dB
to α maxim u m of
1 .5 d
B
over t h e 70 dB d ynamic range .

Sensitivity F
or Α C W Signal
Signal
+
n oise =
Twice noise in L I N
vertical mo d e (see
L OG 2 d B /DI V : P rovides
α cali b rate d 14 dB d ynamic

F
ig . 3-2)
.
T h e
followi ng sensitivity
characteristics apply at
range . Accuracy wit h i n ±0 .4 d B /2
d
B
to α maximum of

50 MH z . Sensitivity
may d ecrease
grad u ally to 2 d B at
1 .0 dB over t he 14 d B range .

1 .7 GH z
an d to
4
d B at 1 .8 GH z .
L I N : P rovi
d
es
α linear d isplay wit h in 10%, over t h e

Sig
n al L evel

R esolution B a n dwi d
t h
graticule h eig h
t .
-115 d B m

300 Hz
-108 dB m

3 kH z
R eference L evel

-100 dB m

30 kH z
-90 d B m

.3 MH z
Calibrate d levels in d eca de ste p
s, from -100 dB
m
to

-80
d B m

3 MH z
+30 d B m,

wit h i n ±2 dB .

(I n clu d es
attenuator and gain
switc h ing effects w hen t he two are
not off-setting eac h
ot h er .) R efere n ce level d eviation b etween d isplay
modes is
;

IntermO d ulat ί on Distortion (See Fig .
3-6)
less t
ha
n 2 dB from 2 dB /DI V to 10 dB /DI V and less t han

T h ird order is d
ow
n70
d B or more from two
-30 d B m
0 .5 d ivision from 2 d B /DI V to L I N . N ote : T h is d eviation is

signals wit h in any fre quency
s p a n . Seco nd or d er
is d own
α
function
of t h e oscilloscope vertical linearity .

70 dB or more from two-40
d
B
m signals .
Calibrator

Sp urious Signals F rom
Internal Sources
50 MHz ±0 .01% wit han absol u te
amplitu d e level of
-30
dB
m
±0 .3 dB, at 25 ° C .
RF
Attenuator
( R
esi d u al R esponse)
Eq ual to or less t h
an -100 d Bm, referre d
to t
he
1st
mixer in p ut .
Cali b rated 10 d B ste p s . Accuracy ;
±0 .2 d
B
or 1% of d B
Inci d
ental FM (See F ig . 3-5)
rea
d
ing, w
h ic h ever is greater .

200 H z
(P-P) maximum, w hen ph
ase loc k e d , or 20 kH z
(P-P) maximum
in 5 secon d s, w h en
ou t of ph ase loc k mo d e .
Gain
F ou r selector positio
n s, b or d ered by
α blue sector,
Stability
p rovide
30 dB of
ch
ange, in 10 dB steps, for t he
10 dB /DI V

W it h in

50 kH z,

over

α

1

h ou r p erio d
at α fixe d
d is p lay
mode
. T
h ese four, p lus fo u r a d ditio n
al
p
ositions,

tempe r at u re, w h en p h
ase loc k e d . W it h in 100 kH z
w
hen not
p rovi d e 70 d B
of
gain
ch ange for t h e 2d B /DI V
and t he L I N

p
h ase loc k e d over
α
1 h
ou r perio d , at α fixe d tem p
erat u re .
mo de d isplays .
Accuracy

is with in ±1 d B
/10 dB step to α total of

Maximum
In p ut P ower Level
±1 .5 dB w h en t he V A R IA BLE
control is in its CA L d etent
.

L inear
O pe r ation- RF attenuator at
0 dB
;
-30 dB m .
Safe In pu t levels- RF atten u ator
at 0 d B ;
+13
d B m . RF
Th e

V
A R
IA BLE

control, wit ha
p p roximately 10d13

atte n
uator at 60 dB ;
+30
dB m (1 W
average, 200 W p ea k ) .
ra n ge,
provides continuo u s gain a dj ustment
b etwee n eac h

NOTE : Th
ese are i nput levels to t he
1st mixer and t h e
calibrate d step .

power rating
of t he atte n uator .

Sweep Rate

t he SINGLE
S WEEP mode . Sweep
automatically recurs at
Calibrate d sweeps, from 10 ms/Div
(SPECTRUM posi-

the end
of sweep holdoff time in the FREE
RUN mo de .
tion)
to 1 μ s/Div (within 2°/ ο ), are
provided in 1-2-5
se q uence . Α
V
ARIABLE
control p rovides
continuous vari-

Vertical O ut p ut
Connector
ation between steps
. When the ΤΙΜΕ /DIV selector
is in the

P
rovides 50 mV
±5°/ ο vi deo signal per d
isplayed d ivision,
SPECTRUM position,
the r ange of the V ARIABLE control

about

the

CRT

vertical

center .

Source im p
e d ance

is
is increase d a p proximately
100 Χ allowing the Time/Div
to

app
roximately
1 k
Ω
. Α maximum of 50 mV
offset may b e
be increased to about 1 s/Div .

intro duced by
error f rom the mainframe
vertical centering
interface .
Triggering
Specifications-7L12
Signal
source is AC coup le d from either
the vertical
H orizontal Input
Connector
amplifier channels
or the p ower line . Frequency
range is

R eq uires α 10 V
±1 V
signal,
with α starting reference
of
approximately
15 Hz to 1 MHz . Sensitivities
for t he trig-

0 V ±1 V from
α low
impe
d ance (300 Ω or
less)
source,
to
gered modes are :
1) <0 .5 division for the Ρ - Ρ AUTO
mo de

normalize

the

external

sweep

voltage

to

the

7L12
2) <0 .3 division for the N ORM
mo d e 3) <1 .5 division
for

frequency span .

O
PER ATI N
G
I N
ST RU CTIO N S
T h e first ste p s of t he Ge n eral
Operati n g informatio n
cali b rate an d ch ec k t h e analyzer Fre q uency
Sp a n /Div and
t h e d is p lay modes . T h ese steps serve as p art of an
acce p ta n ce c h ec k an d d escribe h ow
to o
b
tain α d is p lay on
th e oscilloscope CR T . T he Pe r
fo
r mance
C h ec k section of
th is man u al refers
to
t h ese ste p
s as p art of an acceptance
ch ec k o u t p roce d ur e .
P erformi ng this O p erational C h ec kout p r oced ure,
is
recommen d ed to ac q uai n t you wit h t h e f u nctio n s
of t
he
cont r ols an d selecto rs a nd t h e ove r all operation of t he
7 L 12 .
Α safety latc h , i n add ition to t h e f r o n tpanel release,
m
u st be released before t h e 7 L 12 can be pulled from
t h e oscillosco
p
e
com
p
artment . The u nit will pull out
par
t
way
w h
en t h e
fr
o
n
t
panel r
elease is pu lle d , t he n
t h e spri ng safety latc h mu st be
pushed up before t he
un it will pull t h e r est of t he way
out . T
h
is safety
latc h is locate d un d erneat h t he r ig h t r ail near
t he
front cor ner (see F ig . 2-1) .
T r
iggering
SO UR C E
CA U TIO N
Sectio n 2-71_12
Introduction

515 Hz to >1 MH z . T he ΙΝΤ pu s h - bu tton, selects t he input
signal to t he 71_12 as t he trigger source . T he L I NE
T h is sectio n d escri b es : 1) Installatio n of t he 71_12 i n
to α

pus
h - b utton, selects α sample of t he p ower li n e voltage as
7000-Series Oscillosco pe . 2) Function of t he front p anel

the trigger source . Α t h ir d p us h - b utto n ca u ses t h e swee p
controls, selectors, indicators and connecto r s . 3) Ge n eral

circ u it to free ru n .
op eratio n i n formatio n , such as ; ad ju stmen ts re qu i r e d to
mate t he 7 L 12 to α 7000-Series Oscillosco p e, signal
application to t
h
e
RF
i np ut, h ow to use t he cali b rator for
accurate fre qu ency an
d power level meas u remen ts, etc . 4)1

MOD E
Some ty p ical app lications .
Ρ - Ρ A U TO : Triggering occurs at t he level
a
nd slo
pe
selecte d by t he LEVEL and SL O PE co n trols . T h ep ea k to
pea k trigge r signal amplit ude r equ i r e d for ΙΝΤ triggeri n g
must eq ual or excee d0 .5 d ivision . If trigger sig n al is a b se n t,
or beyon d t he am p lit ude an d fre q uency limits s p ecifie d , t h e
sweep will free run (after h ol d -off time) at t he rate selecte d
b y the ΤΙΜΕ /DI V selector . T he LEVEL control range
a d a p ts to ch anges in the triggering signal am p litu d e so its
ra n ge corres po nd s to t he p ea k to peak signal am p lit ud e .
N O RM : Triggering occurs
at t
h e level
and slo p e selecte d
b y t he SL O PE and LEVEL controls . T he minim u m signal
am p litu de for triggering must e q ual or excee d 0 .3 d ivision
on the display . T he LEVEL control selects t he sig n al
am
p
litu de level . Triggering does not occu r , w he n t he setti ng
of t h e LEVEL con trol is b eyo nd the sig n al am p litude level .
SI N GL E S W Ρ : After
t
he RE ADY in
d icator is lig
h
te d ,
triggering will occur w h en t he signal
ap p roac h es 1 .5
d ivisio n
s of am
p lit u
de . Swee p is initiate d as t he signal
am p litu de
and
slo
pe pass t
h
ro
ugh
t
h
at selected b y t h e
SL O PE an d LEVEL co n t r ols . Th e circuit
must b e r eset b y
p u s h ing t h e RE S E T b utton b efore an ot h er sweep
can be
t r iggere d .
RE S E T- RE ADY : Α pu s hb utto n t h at resets t he t r iggeri ng
ci r cuit for si n gle sweep operation . RE S E T- RE ADY bu tto n
FUN CTIO N O F
THE FR O N T P A NEL

lig h ts w hen p us h e d , to in d icate t h at t h e circuit is r ea dy to
CO N T R
O
L S AND
AD JUST MEN TS

be trigge r e d .
Eit he r the vertical
chan nels o r t h e power li ne may b e
selecte d as t he trigger
sour ce, b y the front pan el push-
buttons . It is AC co up le d a nd h
as α fre q uency ra n ge from
LEVEL
Α cont r ol t h at selects t h e am p lit ude
at
w h
ic
h
triggering
occ ur s for t h e va r io u s triggering modes .
SL O PE
1 T EK T RON IX Meas ur e m en t
Con ce
p
t boo k let ; "S p ectr u mA n alyze r
Meas ur ements T h eory
and Practice" . Part No . 062-1334-00 is

Α
switc h that selects t he (+) positive
or (-) n egative
recom m e nd e d tr
eatise on app licatio n s a nd m eas ur ement eval u atio n .

slo p e of t he sig n al for triggeri ng
direction .

O p eration-7 L 12
2-2
F requ ency r ea do ut fo r ST A R T or
C E N T ER of t h e d isplay .
FI NE t un i n g con trols
t h
at
are
used in t hep h ase lock ed m o de
wit h FREQ S P A
N
/DI V 0 .1
MHz
or less .
A b sol u te le vel at t
h e top of t he
gratic
u
le w it h r efere n ce to t he
settings of t
he R F atte nu ato r
and
Gai
n
selecto
r .
In
10 dB /Div mo d e
Gai n selector
m u st be i n b l ue
secto r for read i n gs to b e ap pli-
cab
le .
RF I n p ut con n ector .
Input im-
pedance 50
Ω .
Pull t
h
is latch to f r ee instrument
f r
o m t h e m ai n fra m e i n terface .
Safet y
latc
h
und er right r ail mu st
be release d by pu shi ng up on the
spring latc hbefo r e t h e
71-12 will
pull
co m pletel y
out of t he i n str u -
me n t .
W h en de p resse da nd t h e F RE Q
S P A N /DI V setti ng is less th an
MAX SP AN , the FRE Q
UEN CY
rea d o u t is the cen te r or STA
R
T
of the d is play .
Cali b rates
LOG display acc ur acy .
Sig n ifies w he n
lig
h ted,
th
at α
fre-
qu
e n cy ma rk e r
is
d is p laye d . T h is
ma rk er indicates
t h
at p
o r tio n of
-t he 1 .8 G H z
span
wh ic h will b e
displayed wh
e n the FRE Q S P A N
is re duce d f r o m t h e
MAX SPAN
positio n .
M ai n t un i n g co n t r ol fo r t h e fre-
quency .
Gain
selector . Switches gai n in
10 dBsteps . B l ue
sector
appli-
cable
to 10
dB /DI
V mo de .
V A RIA BLE Gai n
control .
RF atte nu ator selector an d r ead -
o ut . S w itc h es in 10 dB steps .
ΜΑΧ I N PU T rea
d
o
ut cha n ges to
correspond
w it h atte n uator set-
tings .
Sets t h eR
EFEREN
C
E LEVEL to
t he top g r aticule li n e
.
F ig
. 2-1
Α . Co
n t r ols, selecto r s an d i n d icators t h at r elate to t h ed isplay, f r e que n cy, dy na m ic ra nge, and refe r e n ce levels
.

Vi
d eo
bandpass
is
r
e
d
uce
d
as indi-
cated w hen t h ese pus h butto n s are
depr esse d
2
ο
filter
h ig h fre q uen cy "
co mp o nents s u ch as n oise .
P u lse d RF is stretc
h ed , w hend e-
p ressed, so spect r a is enhanced ._
Use d w it h w
i
de
fre qspa n s
and
resol u tio n band widt h s
.
I np ut
j ac
k for a p plyi ng extern al
swee
p f r om
αreco
r d er .
Selects sweep rate
. T h e S PEC-
T RU M p ositionp rovi d es
10 ms/Div (V
A RIA BLE in CA L
)
and is use d p r i m arily for fre-
que n cy d o m ai n d is p lays . A MPL I -
F I E R p ositio n , is use d w h e n an
exter n al swee p sou r ce (at t h e
HO R IZ IN j ack o r L eft V ert
Plug-in) is used .
Ι
RE SO LU TIO N selector and
r
ead
-
o u t w i ndo w .
V ideo ou tput sig n al for reco rd er
O pe r atio n -7 L
12
V
A
R IA
BLE
ΤΙΜΕ /DI V co nt r ol .
R ange increase d to 100 Χ w hen
ΤΙΜΕ /DI V selecto r is i n
S
PE C-
T RUM P OSITIO N . ( P ushto un-
lock) .
A dj usts t
h e ratio of b rig htness
between
t
he cli pp
e d baseline
and
t h e
r
e
m
ai
n i n g d
is p lay .
Co
mp ensates for d iffere n ces of
oscillosco p e d eflection
sensitiv-
ities .
Co n trols the am p lit u d e (a bove t h e
baseline) of t
h e cli pp e
d (su b du ed)
portion .
U sed wh
en FR E Q
S
P A N <100
kH z/Di v to switch
p h
ase lock on
or off
.
VA RIA
BL
EFRE
Q S
P
A
N
control
-" (
P u s hed to unloc k ) .
Pull o u t to u n co up le RESOLU-
TION selector from FRED S P A N /
DI V so eac h can be set
independently .
Safet yL atc h : Push
up on s p
ring
safety latc h to r elease i n str u me n t
after it is pa r t way out .
F ig
.
2-1 Β . Controls a nd selecto r s t h at relate to thed is play ; swee p , frequen cy span, resol u tio n , vi d eo p rocessi n gand phase lock
.
2-
3

Operation-71_12
H orizontal Swee p

VER T
OUT Co
nn ector
ΤΙΜΕ /DI V
Selects cali br ate d
sweep rates (V A R IA BLE
con
trol
pus
h
e d
in) from 10 ms/Div . (S PE CT RUM positio n ) to
1 μ s/Div,
i
n α 1-2-5 se
q uen ce .
An
AM PL I F I ER p osition
allows t h e analyzer to b e swep t from an exter n al source .
T
h e S
PE
CT
RUM
position provides α cali
b
rate d
10 m s/Div sweep rate an d increases t
h
e range of t
h
e
VA R IA BLE control to 100 Χ , w h ic h allows the Time/Div to
b e i nc r ease d to a ppr oximately 1 s/Div for s p ectr u m a n alysis .
T he A MPL I F I ER positio n is use d to sweep t h e un it from

CO N T R AST
an exte rn al swee p so ur ce w h ic h can be ap p lie d t hr o ugh one
of t he Vertical Am p lifier units or t h roug h t h e H O
R
IZ IN

A dj usts t he br ig h tness ratio b etween t h e cli pp ed (s u b-
co nn ector on t he 7L12 . Exter n al swee p may b e use d to

d
ue d ) baseline and t h e un cli pp e d d is p lay . Dis p lay intensity
slave t h e spectrum a n alyzer to α r eco r d er or ot
h
er external

is set b y t he oscilloscope
I
n te n sity cont r ol .
d evice .
VA R IA BLE
Pr ovi d es con ti nuous a d ju stment over t
h
e
ΤΙΜΕ /DIV
range .
T
h e V
A R IA BLE
control ra
n ge is i n crease
d
fro m 3
Χ
to 100 Χ in t
he S PE CT RUM p osition .
S
WEEP
CA
L
Cali b rates t he amplitude of t he sweep voltage to t he
FRE Q S P A N /DI V circuits and com p e n sates for differences
in d eflectio n sensitivities b etween oscilloscopes .
H O R IZ POS
A
d ju
sts
the
h
orizo
n tal ce n teri ng of t h e d isplay
.
H O R IZ IN J ack
U sed to apply t h e h o r izo n tal (sweep) drive
d irectly,
from αch a rt r ecor d er or oth er d evice, to t he 71_12
h orizontal circ u its w h e n t he ΤΙΜΕ /DI V selector is switc hed
to the A MPL I F I ER p osition . R e q uires α sweep voltage
of
0 V to 10 V ±1 V, from α
low
impedance
so
u
rce .
T
h
e
±1 .0 V tolerance, at t he u pp er end , is use d to cali b
rate t
h e
external voltage ram p , ma k ing t he fre q uency s p a n of t h e
7Ll2 acc u
rate
.
Provides ±50 m V of vi deo signal p er d is p
layed
division .
T h e am p litu d e a nd p olarity of t h is signal is relative to t he
gratic u le vertical centerline . Source impedance
is a
bout
1 kn . T he sig n al ca n b e used to d rive
an
external recor d er .
Dis p lay Controls and Selectors
BAS EL I NE CL I PPER
Controls t he vertical am p litu de of t h at p ortion (baseline
p lus signal) of t he d is p lay t h at is d ecrease d o r subdued in
inte n sity .
VID
E
O FI L T ER S
T h ree filters
(30 kH
z,
300 Hz and 3
Hz)
can b
e
switc
hed
in to restrict t h e video b an d wid t hand re du ce h ig h
f r equency com p onents . Two pu s h-bu tto n s select 30 kH z or
300 H z w h en dep resse d individ u ally and 3 Hz is selecte d
w
h
en b ot h b utto n s are push e d in .
VID E O PR OC E SSO R
E
n h ances the visibility of p ulse d RF sig n als with in wi de
f r e q uency spans an d resol u tion ban d wid t h s b y stretc h i ng
t he fall time of p ulse d sig n als .
FRE Q SPAN /DI V
Selects t h e f r equency s p an (0 .5 kH z/Div to 100 MH z/
Div
i n α 1-2-5 se quen ce) for t
he
d isplay . T he VA RIA BLE
co
n
trol must be
pus he d in for
α
cali
b rate d dis p lay . Two
a d d itio n al positio n s, MAX SP AN an d0 are
also p rovi d e d .
T he MAX SP A N position, increases t he fre qu ency s p
an to
app r oximately 1 .8 GH z . Α fre quen cy ma rk er n otc h is
also
d is p laye d to in d icate w h at p ortion of t he spectr u m will b e
displaye d w hen t h e FRE Q S P A N /DI V is red u ce d . T h e Ο
positio n co n verts t he analyze r to α t une d r eceiver, for time
d omai n d is p lay . Time analysis of signal cha r acte r istics,
wit h in t he band wi d t h capa b ilities selecte dby t h e RESOLU-
TION setting, can t hen be a n alyse d .
CA UTION
T he FREQ SPAN knob provides
ease in
switching ;
VER
TICA L Control and Output Co n nector

however, if excess torque is
applied
after the switch is
VER T P OS

i n either its full CW or CCW position, the
aluminum
bushing inside the k nob may slip . This will misalign
P ositio n s the C RT b eam vertically .

t he coupling between t he RESOLUTION and FREQ

SP A N
selecto r s . If t he coupling is misaligne d ,
t
h
e

dBm) of t h e to p g r atic u le li ne . REFEREN C E LEVEL is
selectors will d
ou
b
le d ete n t o r switc h wit h α g r in d ing

also d is p laye d
on CR T's of oscillosco p es with r ea d o u t
n oise . R efer to Kn
o
b
R emoval a nd Installation

feat ur e .
i n
structions i n th e M ai
n
tenance section of t h e man u al
for realignme
n t .
VA R IA BLE (FRE Q SP AN /DI V )

Α bl u e tint bor d ers t h e10
dB IDI Vd is p lay switc h ,
Push-push type switc h an d control .
Wh e n it is ou t of its

an d fo ur p ositio n s of the
Gain selector, T h is is
to
correlate REFEREN CE LEVE
L rea dou t to Gai n
CA L d etent, t he control pr ovi d
es va
r
ia b le freque n cy s pan

switc h settings that a r e a pp
licable in t he 10 dB lDl V
between each step of t h e FRE Q S P A N /DI
V selector . T he

dis p lay mo d e . R ea d ings ou
tsi d e t h e blue sector are
co n trol m u st b e i n t he CA L d ete n t fo r cali b
rated
FRE
Q
S P AN d is p
lays .

e r r
oneous b ecause the gain is elect
r ically loc ke d o u t,
T h e
C R T r ea d out will d is p lay the
< symbol to
signify
t he rea d i n gs are er r oneo
us . T h e d ynamic
RE SO LU TIO N

win d ow
of the d isplay will n ot
excee d -130dB m
(REFEREN
C E LEVEL of 60dB m p
l u s 70 dB
Selects

five

cali b rate d resol u tio n

b an d wid t h s, f r om

d ynamic
range of t he 10 dB /DI Vd
isplay)
.
/ η t he
300 Hz to 3 MH z (wit h i n 20%), i nd eca d e
ste p s . S hape

2 dB lDl V d is p
lay mo d e, t he f u ll 70 dB range of
t h e
facto r of t he respo n se, over t h e 60dB to 6 dB amplitu
d e

Gain selecto r is
usable . Switch ing t he Gai n fully
C W
levels, is 4 :1 or b etter .

with t he RF attenuato
r at 0 d B, p rod u ces
an acc u rate
-100 d 8m r eference
level . T he d yn amic range
of t h e
d is p lay
is now -114dB m (-100 d Bm
plus 14 d 8
PULL TO
UNL OC
K

graticule wi nd
ow, to t h e 7t h gr atic u le li n e) .
Α
con
cent r ic
sleeve aro un d t h e VA R IA BLE cont r ol t h
at
u nloc ks t he RESO
LU
TIO N
from t he FRE Q SP A N /DI V
selector,
an d allows
eac
h selector to b e in dep e nden tly set .
L OG 10 dB /DI V
Selects α d isplay
mo
d e with
α cali b rate d d ynamic range
of 70 d B (to t he
7t
h graticule
li ne from t h e to p ) at
10 dB /DI V . T he b ottom gratic
u le d ivision is not cali b rate d .
L OG 2 dB /DI V
Wh en t h is b u tton is dep resse d , t he
dynamic range of t he
display is α cali b rated 14 dB
at
2
dB
/DI
V .
L I N
Selects α li n ear d is p lay, t h at correspo nd s
to t
he
linear
cali b ration on t h e left si de of t h e g r aticule overlay
.
REFEREN
C E LEVEL, RF Attenuatio n ,
an d
M
AXim u m
Powe r L evel
I
nd icato r s and Selectors
Concentric controls t h at
ar
econ
n ected i n an
electro-
m ec h
a n ical d ifferential a r ra n geme n
t w h ic h select i nput
atten u
atio n and i nstrumen t gain .
VA R IA BLE (Gain) Control
ΝΟΤΕ
Operatio n
-71-12
Pr ovi d es at least 10 dB of gain va r
iatio n .
T
he
REFER-
EN C E LEVEL rea d out
on t
h
e CRT
ch
anges to t h e <
sym b ol to i nd icate an u n
calibrate d con d ition w hen it is out
of its CA L d etent . T he
readout of t
he
REFEREN C E
LEVEL window on t h e 71_12 is
only ap p
lica
b le w h en t h is
co n trol is in its CA L d etent .
FRE
Q UEN CYMH z
Dial r ea d s o u t t he STA R T-C EN T ER
or
MA
RKER
fre quency
of t h e d is p lay . Fre q uency and d ial rea
dout are
tu n ed b y the COA RS Econ
trol .
De p ressing t he STA RT pu s h-b
utto
n,
selects t he start of
t he d is p lay or left (ze r o) gratic u le li ne
as t
h
e fre que n cy t h at
is
i
nd icate d b y t he d ial r ea d out . De p ressing
t
he
C EN
T
ER
p us h -b
u
tto
n
selects the ce n ter of t he d is p
lay as t he
fre quency
i n dicate d in t h e r ea d out wind
ow
. Wh en
t he
FRE Q SP A N /DI
V is switc h e d to MAX SP A N p
osition, the
MA RKER i nd
icato r is lig
h
ted an d α notc hon the b aseline
of t h e d is p lay i nd
icates the ce n ter of t h at p ortion of t h e
s pa n t h at will bed is p
layed w
hen
t he FRE Q S P A N is
reduce d .
T
he I np ut atten u ation (f r
om 0 dB to 60 dB) and Gai n

F
I NE Fr equency Co n trols
(0 dB
to 70 d
B)
are selecte d in 10 d B
steps . An electro-
mec ha n
ical arra n ge m e n t a nd r ea dout win
d ows esta b lis h an d Two concentric con trols t h at p
rovide fine tuning ad j ust-
indicate
to t
he
user, MAXim u m p ower in pu
t
level
(in dBm),

ment d u r i ng ph ase loc kop eratio n
or at s p ans w h ic ha r e
RF atten u
ation (i n
dB),
and t he REFEREN
C
E
LEVEL (i n 0 .1 MH z/Div or less .

Operation-7L12
L OG a nd AMP CA L Ad j ustments

7000-Se r ies Oscilloscope .
Ens ur e
t
h
at t
he 71_12 is securely
T h e L OG a dj ustme n t cali b rates t h e logarithmic dis p lay

latc he d in
t
he com partmen
t so it cannot fall out if t he
accuracy a nd t he AMP ad ju stmen t sets t he REFEREN C E

oscillosco
pe is ti
pp
e d
forwar
d .
LEVEL to t h e top graticule line .
AU TO PH AS EL OC K Switc h
U se d , in t h e p h ase loc ked mo d es, to d isa b le th e ph ase
loc k . T h e COA RSE t un ing cont r ol will t hen tune t he center
fre q uency wit hou t t h e 1st L
O ju m p
i n g b etween loc k
p
oints . T h
is p rovi
d es
α
wider tuning ra n ge t han t h
at of t
h e
F IN Ε controls .
CA
L
OU
T Connector

d . A
d j ust t
he
oscilloscope Intensity, Foc
u
s and Astig-
matism controls for optim u m display d efinition wit h
P rovi d es an accurate -30 dBm, 50 MH z sig n al . T h is

n ormal intensity .
signal pr ovi d es an a b solute reference on t h e d is p lay to
ch ec k d B m rea d ings an d calibrate t h e REFEREN C E
LEVEL . H
armo
n ics
of
t he 50 MH z f undamental provide

e . Depress t he 2 d B /DI V dis p lay mode button . P osition
pic k et fe n ce mar k ers across
t
he fre q uency
span
for acc u
rate

t
h
e b aseli ne of t
h
e d isplay to t
h
e b ottom
g
r atic
u
le
line
wit
h
fre q ue ncy andsp
a
n measureme n ts .

t h e VER T POSition
con
trol
and
ce n ter
t
he d is p
lay
wit h t he
H O R
IZ
P
OSitio
ncon trol .
RF I Np ut Connector
Α 50 Ω i nput con nector for a pp lyi ng t he input RF signal
to t he 71_12 .
REFEREN CE LEVEL
in d icator refers to t
h
e
RF level
at t
he RF I Np ut . R efer to General O p erati ng
Information in regar d s to sig n al app lications .
G ENER A L O PER ATI NG I NF O RM ATIO N 2

Wh
e n t h e oscillosco p e has α CR T wit h Ρ 7 ph osp ho r, α
viewing
h oo d will help s h iel d am b ient lig h t and
en h a n ce t he d is p lay information .
Th is section d escri b es h ow to mate t he 7 L 12 to α
7000-Series Oscilloscope an d h ow to u se th e main feat ur es
of t he instr u ment i n ma k i n g various measurements .
ΝΟΤΕ
E
xter nal
graticules
are d esigne d so t h ey will compen-
sate
for parallax of t h e came r a . Gratic u le mar k ings
will t h erefore be co r rect on ph otog r ap h e d d is p lays .
Instructions on h ow to instal/ g r aticule over lays, will
be foun d i n t h e mainframemanual un
d er t he s u btitle
lig h t filte r s .
li n e wit h t h e H O R ΙΖ POS cont r ol .
1 . P reliminary F ront Panel Setup an d Calibration
P rocedure to M atc h t h e 71_12 to t h e Oscillosco pe
Deflection Sensitivity

ε . Co nn ect t he CA L O U T sig n al to t h e RF I Np ut,
α . P l u g the 7 L l2 Sp ectr u mA n alyzer into the center two

d
ec r ease t h e FRE Q SP AN /DI V to 50 MH z a nd t u ne the 5t h
compartme n ts, of α four p lug-in 7000-Series Oscillosco p e,

mar k er (250 MH z) to t he center gratic u le line (see Fig . 2-3) .
or into t he rig
h
t two com
p
ar tments, of α t
h
ree plug-in
2 Α t r eatise on sp ect ru m a
n alyze r m eas ur e m en ts a
nd
a pp licatio n
s is
co n tai ned in T EK TRON IX Meas ur e m e n ts Co n ce p t Book let ; "Spec-
t rum A n alyze r M eas ur e m e n t T h eo r y a n d Pr actice :", Pa r t No .
062-1334-00 .
b . Co n nect t he oscillosco p e mainframe to α suita b le
p ower source an d switc h t he PO WER on . Allow ab out 20
to 30 minutes for i nstrumen t sta b ilization .
ε . Set t he fro n t p anel controls as ill u st r ated in Fig . 2-2
an d connect the CA L OU
T
sig n al t h roug hα s h ort coaxial
ca b le to t h e RF I N put .
f . De p ress t he 10 dB /DI V ( L OG) d is p
lay b
u
tto n . Dis-
play s h oul d now resemb le t h at s h own in Fig . 2-2 .
ΝΟΤΕ
2 . Calibrate t he Swee p S p an
α . Switch t he
FRE Q
SP
AN /DI
V to MAX S
P A N
posi-
tion,
en sure t
h
at t
he
VA
R IA BLE ( F
re q Span) control is
p us hed in .
b . P osition t h e 0 Hz res p onse on t he zero (left) graticule
d . Cali b rate t h
efre
quency s p an to 50
ΜΗτ /Div
by
a dju sti ng t
he S WPCA L for 1 mar k er/divisio n . It will be
necessa r y
to k
ee p t he 250 MH z ma rker cente r ed with t he
COA RS E FRE Q UEN CY control as t h e swee p is cali br ate d .
Fi n al d is p lay sh o u ld resem b le t h at illustrate d in F ig . 2-3 .

Top li ne is d B m
level i nd i-
cate d
in REFEREN CE
L EVEL wi n d ow
VIDEO PR OC E SSO R :
Switc h Ou t
I N T EN SIT Y : CC W
F OC U S : M i d ra nge
ϊ
FRE D S P A N IDI V : 50 MHz
Operation-7L12
BOTH
VID E O F I L TE R S :
S w itc h es O u t
Sleeve pushed in so FREQ
SP AN an d RE SO LU TIO N
are co up led toget h er .
F ig . 2-2 . 7 L 12 S p ectr u m Analyze r in α 7000-Series oscilloscope ill u st r ating initial setti ngs of f r ont p a n el controls a nd selecto r s . Circle d ( Ο )
pus hbu ttons d e n ote bu tton depresse d or positio nof selecto r .
2-7

Operation-7L12
F ig . 2-3 . Cali b rati ng t h e sweep s p a n .

F ig . 2-4 . Calibrati ng t h e L OG a nd RE F EREN C E LEVEL of t he dis-
play
(Do ub le ex p os u re to
illustrate
t h e two d is p lays wit h reference
to eac h ot
h e r
) .
3 . C h ec kan d A d j ust LOG-AMP
Calibration

graticule d ivisions . Am p litude ch ange sh ould eq ual 5
d ivisions at 2 d B/D I V .
T he L OGCA L a d j
ustment cali b rates
t
he d isplay so it is
logarit h mic . T he
AMP CA L a d j ustment sets the reference
level to the top
graticule line . T here is no interaction
between t h ese two a
d j ustments .

f . If t he ch ange is more t han 5 divisions
(e
.g ., am p litu de
d ecreases from 8 to 2 .5 div .), ad j ust L OGCA Lto furt h er
d ecrease t
he signal
am
p
litu d e or increase t
he
am
p litu
d e
α
.
Set t h e 7L 12 selectors an d controls as d irecte d in step

change . Conversely if t h e c h
a
nge
is
less
t
han 5 divisions
2 an d
tune t he fundamental 50 MH z calibrator signal to t he

(e
.g .,
am p litu d
e c h anges from
8 to 3 .5 div
.),
ad ju st t
he
L
OG
center of t
h e graticule .

CA L to increase t
h
e signal
amplitu
d e . NOTE : Correct for
ap p
roximatel y1/2
t
he
total
i n
dicate d error
. T h
is ad j ust-
ment
may
seem
opp
osite
to
w h
at
is expected
;
h owever, th e
b . U ncou p le

t he

RE SO LU TION selector

from

t
h e

L OGCA L
ad
j ustment s h ifts t he reference level ma k ing t h e
FRE Q S P A N /DI V , by p ulling ou t t h e PULL TO
UNL OC K

net result α correction to t h e am p litude c h ange .
sleeve, th en switc
h
t
h e FRE Q S P A N /DI V to 5 MH z . T h
e
RE SO LU TIO N s hould remain at 3
MH z .
As t
he FRE Q
SP A N is d ecrease d , it may b
e necessary to re-a d j ust t h e

g . Switc h out t he 10 d B of RF Attenuation . Ad j ust t h e
tuning control to keep t he signal
centered
on
screen .

AMP CA L to return t he signal level to t he reference line .
( Ensure t hat t heb aseline of t h e d isplay is still on t he
b ottom graticule line .)
c . Switc h t h e Dis p lay M o de to 2 d
B /DI V
an
d position
t
h e b aseline of t h e d isplay on t h e b ottom
graticule line with
t h e VER T P OS control .

h . R epeat t h ese ste p s until t h e 2 dB /DI V L OG dis p lay is
calibrate d (see F ig . 2-4)
.
R eturn t he RF Attenuator to 0 dB
(REFEREN C E LEVEL -30 dB m), t h en ad j ust AMP CA L
d . A d j ust the AMP CA
Land
t
he L OGCA L (if neces-

to p osition the to p of t he -30 d B m signal on the reference
sary) to b ring the 50 MH
z signal wit h in t h e graticule win-

line . E nsure t h at t h e -30 d B m sig nal is 8d ivisio
nsin
dow . A d j ust t h e AMP
CA Lto establis h α signal reference

am p litu de .
am p litu d eof8d
ivisions ( F ig . 2-4 s h ows α full screen dis-
play) .
i . C h ange

t h e

d isplay

modes

from

2d B /DI V to
10 d B /DI V , t h en to L I N . Signal am p litu de reference le
v el
e . Switc
h in
10d13
of attenuation with t h e RF Atten-

s hould not c h ange more t h an

2 dB
from

2 d
B /DI V to
uator and
note t h e am p litude c h ange of t he signal in

10 d B /DI V , or 0 .5 d ivision from
2
d
B/DI V
to
L I N mo d e .
2- 8
0 H z r espo nse
Set 250 MHz (5t h ) ma rk er at t he
gratic u le ce nter wit h H O R IZ P OS
con trol
.
Afte r LOG is cali b rate d a dju st
AMP, wit h -30 dB m
signal, so to p
of g r atic u le r eprese
n
ts -30 dB
m .
11

2d

d is p lay
~

mo d
e f o r
amplitude
Ilk,
n geof~ divisions
'
ιιιιια r ιιιιι
~ ι 01 01
ι
11 ιΙΝΝιι
ιΙΝΝΕ ® ιιΙΟ ®® E!
B aseli n e of t h e d is p lay m ust be on
t h e b ottom gratic ule line .

4 . C h ec
k t h e 10d B /DI V and L I N M o de Dis p lay

g .
R eturn t h e RF attenuator to 0
dB,
t
h e VARIABLE
O p eration

Gain control to CA L . T h e signal am
p litude s h ould ret u rn to
full screen an d t h e
REFEREN C E LEVEL s h o u ld in d icate
α .
After completi ng t h e

L OG CA L and AMP CA
L
-30
dB m .
ad ju
stments, d escri b e d i n ste p 3, d epress t h e 10 d
B /DI V
b utton,
ensure t h at t h e RF attenuator is at 0d
B
and t
h e
Gai n
selector is fully CC W so t h e
REFEREN C E LEVEL

5 . A d j ust Co
n trast an d C h ec k B aseline Cli pp er
rea d s
-30 d B m .

Operation
b .
Switc h t h e FRE Q S
P A N /DI
V to 1
MH z
andt
h e
RE SO LU TIO N to .3 MH
z .
Center t
h
e 50
MHz mar k er to
t h e graticule cen ter .
ε . Increase t h e RF atten
u
ator
setting in 10 d B ste p s and
note t h at t h e sig n al am
p litu d e d ecreases 1 d ivision eac h
ste p .
d . Switc
h
t
h e RF atte n uator bac k to 10 d B , an d depress
t h e L
I N
d is p lay
mode b utton .
e . E ns u re t h at t h
eb aseli n e of t h e d isplay is at t h e
b ottom graticule line, and t
h e 50 MH z sig n al is centered
t h en a d j ust t h e V
A R IA BLE Gai n cont r ol for α signal
amplitu de of 6 .3 d
ivisions .
NOTE : V olts RM S--multi p ly 6 γ
2.8
for
peak to p ea k .
0 dB m =
1 milliwatt
N O RM A L O PER ATI N G
R A N G E
F ig .
2-
5 . V olts- dB m- W atts conversio n c h a r t for 50 2 impe d a n ce .
Operation-71_12
T h e contrast ratio t h at is set between t
h e cli p ped
portion of t h ed isplay b aseli n e a n dt h e rest of t
h ed isplay
depe n ds on swee p rate,
FRE Q
S
P A N , RE SO LU TIO N , a n d
am b ient lig h t .
α . W it h t h e
B
AS
EL I NE CL I PPER set mi d range, ad j ust
t h e CO N
T R AST
for t
h e desire d ratio b etween t h e cli p ped
or s u bdue d portio
n
and
t h e rest of t h e d is p lay . ( U sually t h e
co n trast is ad j
ustedso t h e clippe d b aseline portion is j ust
visi b le .)
b . Ad j ust t
h e B AS EL I NE CL I PPER co n trol so t h e
b aseline is su b d
ued
.
If t h ere is excessive noise it may b e
d esirable to clip t
h
is
noise level as well .
1 . Signal A pp lication
U SI
N
GTHE
A N A L YZ ER
f
.
Switc
h
t
h e RF attenuator to 20 d B to a d d10 d B of

T h e
RF I N put im p e d ance to t h e 71_12 is 50 Ω . At h ig h
attenuatio
n ,
and
note t h at t h e signal amplit u de decreases to

f requencies,
im p ed ance mismatc h es b etween t h e
RF I N p u
t
ap p
roximately 2 divisions for α ratio c h ange of 3.16 (t
h
is is

and t
h e signal source can cause reflections in t
h
e
trans-
e q
u
ivalent to
10 d B in L I N mo d e) .

mission line w h ic h degra d es instrument
performance . F lat-
ιι

Ι
Ι 0μ v

100 μv

1 mV

1 O MV

1 OO MV

1 V
Ι

Ι
-IOO dBm -90 dBm -80 dBm -70 dBm -60 dBm -50 dBm -40
dBm -30 dBm
-20
dBm -IO dBm O dBm +IO dBm +20 d8 m
ο .
ΙΡω
ι. ο ρ
ω
ιορω ιοορω
ι. οn ω
ιο n
ω ιΟΟηω ι. ο μ ω ιο μ ω ιο 0μ ω ι. Ο mω ιο mω l00 m ω
M AXI MUM SIG N A L
W IT H O U T DA M AG E ,
TO THE UN IT IS +30 d B m

Operation-702
n ess, se n sitivity, spurious response, etc . are all affecte d . To

d B mV to dB m an d dB m (75 Ω ) to d
B
m
(50 Ω ) t
h
roug
h
re d uce mismatc h , use good quality 50 Ω coaxial ca b le to

matc h ing atte nu ators is s h ow n in Fig . 2-7 and d escri bed
as
co n nect t h e sig n al source to t he
RF I
N put and k ee p t h e

follows :
ca b le as s h ort as possible . Cable losses b ecome
excessive
a bove fre qu e
n cies
of 1
G H z .

( d B m V, i n to 75 Ω ) - (d B m,
at 50
Ω e
nd) = 54 .46 d B
Avoid app lying h ig h level signals (a b ove -30 dBm) to
t h e 1st mixer of t h e 71_12 . H ig h level sig n als overload t h e
mixer an d may pro d uce s p urio u s signals . Α conversio n c h art
is s h ow n in Fig . 2-5 to ai d in d etermini n g in p ut sig n
al
level,
in d B m, μ V, an dμW, from α voltage or p ower so u rce .
The maxim u m p ower inp u t level to t he RF atten-
u ator is 1 watt average o r 200 watts p ea k . Wh en t h e
RF inp u t sig n als are ri d ing on α DC potential, use t h e
DC Bloc k ( P ar t No . 015-0221-00), to preven t t h e
DC
from
r
eac h ing t he 1st mixe r . Wh en t he sig n al sour ce is
75 Ω an d
you
are
using t he 75 Ω to 50 Ω minim u m
loss atten u ato r , α DC bloc k
is not req u ire db eca u se
one is incorporate
d
in t he
atte nu
ator .
The 71_12 can be used with α 75 Ω signal source b y using
α 75 Ω to 50 Ω min imum loss attenuator . T h is attenuator is
availa b le as an o p tional accessory (refer to t he op tio n al
accesso r ies list i n t he catalog or
Accesso r y p age in t he
manual fo r or d eri ng i n fo r mation ) .
Sensitivity and p ower
levels are often rate d in d B m ( d B with refere nce to
1 m W
r egar d less of imped ance) . Sen sitivity and
p ower levels
for
75 Ω systems is us u ally rate d in dB m V ( dB wit h r efere n
ce
to
1 mV across 75 Ω ) . Fig . 2-6 is α ci r cuit diagram of α s u it-
able matching p ad for this p urpose . The conversion from
eg
7592
~
RL
86
.792 ~

50 Ω
.047 43
.392
0- Ο Ο
[11 T h erefore dB mV =
54 .5 + d
B
m ; e .g ., -30 dB m (at
the 50 Ω in p ut) req u ires (-30) + (+54
.5) or +24 .5 dB mV at
the 75 Ω i np ut .
[21

dB m (75 Ω input) =d B m +5,72
(50 Ω output) ;
e .g .,
α -30 dB m in p ut to t h e RF

I Np
ut of t he 71_12
re q uires,
(-30) + (+5 .7) or -24 .3 dB m at t he 75 Ω in p
ut of
t h e pa d .
[31 For some a p plicatio n s you
may wis h to k now t h e
relations h i p b etween dB m an d d B μV .
For 50
Ω
t
h
is is
d B μV = (d B
m) +
107 d B .
T h ese t h ree relations h i p s are s h
own in Fig . 2-7 for easy
grap h ical con version .
Sp u rious response, caused b y signal
overload into t
he
1st
mixer, can b e mi n imize d if t he sig n al amplitude is k ep t
wit
h
in t h
e
graticule limits . Α recomme nde d proce d ure is to
a
d j
ust t
h
e Gain selector for some b aseline noise on t h e
dis p lay, t h en increase
t
he RF
Atte n uator d B setti ng un til
t h e strongest sig n als are with in
t
he
graticule limits . If t h is
does n ot b ring t h ese signals wit h in limits,
a dd ad d itional
external attenuators .
[31
dBμ V
(500)
+87
+35
-24 .7
+15
-44 Ι 7
-5
-64 .7
-25
7
+7

--}--i
-45
+67
+47
+27
0

-104 .7
-107 -100

-80

-60

-40

-20
dBm
(50
Ω
)
F ig . 2-6 . Ci rc u it of α75 Ω to 50 92 m atc h i n g pa d (AC co up le d
) .

F ig . 2- 7 . G r a ph ill u st r ati n g dBm to dB μ V r elatio n s h i p .
[21 [1]
dBm
dBmV
(75 92)

(75 Ω )