Tektronix 7L5 User manual

Te k tro n ix, Inc .
Ρ . Ο . Box 500
B eaverton, Orego n 97077

Serial N umber
070-2184-01
W ARN I N G
T~ J ctro n nc
CO MM ITT E D TO E XC ELLEN C E
THE
F
O
LL
O W
I N
G S
ERV ICI N
G
I N STRU CTIO N S A RE
F
O
R
U S
E
BY
Q
UA
L I F I E D PER SO NNEL ONL Y . T O
A V OID PER SO N A L I NJUR Y, DONOT PERF ORM ANY
SERV ICI N G OT HER THAN THAT CO
N TAI NE D IN
OPER
ATI N
G
I NST
RU CTIO
N
S
UNLE SS YO U ARE
QU A L I F I E D TODOSO .
7
L 5
E c τ R υ
I N ST RU CTIO N M A NU A L
F i r st P
ri
n
ti
n gN
O
V
197 6

Copyrig h t ~
, '1976,1978 Te k tro n ix,
Inc . Al Ι rights
reserved .
Co nte n ts of
t h is
publicatio n may not
be repro d
uce d in
a n y form
wit h out t h e written
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Te k tro n ix, Inc .
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Te k tro n ix, Inc .
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bsidiaries are
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ts and/or p e n
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S E CTION 1

G ENER A LI NF ORM ATIO N

S ECTION 4

CA L I BRATION PR OC E D URE
I n tr o du ctio n a nd Descriptio n 1-1

Co mp lete o r P artial Calibratio n 4-1
Manual Organization

1-2

H istory Information

4-1
Electrical Characteristics

1-2

Interaction

4-1
Frequency

1-2

Equipment Required

4-1
Input

1-3

Short Form
Procedure and Record

4-2
Amplitude

1-3

Preliminary Procedure

4-3
Sweep

1-4

1 .
Check/Adjust
the
Reference
Output Connectors

1-4

Oscillator Frequency

4-6
Environmental Characteristics

1-5

2 . Check/Adjust the
Calibrator
Physical Characteristics

1-5

Output L evel

4-6
Accessories and Options

1-5

3 . Frequency Span/Div Calibration

4-7
Installation

1-5

4 .
Sweep Timing

4-9
R epackaging for Shipment

1-6

5 . 1st L O and 1st L O Phase L
ock
Calibration

4-10
SECTION 2

CIRCUIT DESCRIPTION

6 . Function I F Calibration

4-11
B lock Diagrams

2-1

7 . Calibrate the 250 kHz, 2nd
I F Processing Chain

2-1

M
ixer,
and 10 .7 MHz Input F ilter

4-12
Sweep Control and Frequency

8 . V ariable
Resolution Calibration

4-13
R eference

2-2

9 .
Digital
Storage Calibration
Frequency Control Circuits

2-3

(SN Β
069999 a nd below)

4-16
Readout

2-5

9
Α .
Digital Storage Calibration
Display Processing

2-6

(SN Β
070000 a nd up)

4-18
Detailed
Circuit Description

2-7
Sweep Control

2-7

SECTION
5

M AINTENANCE
Trigger Logic and Sweep

Introduction

5-1
Control

2-11

Preventive M aintenance

5-1
Frequency
Span and Readout

2-13

Cleaning

5-1
Tune Reference = Ν L oops

2-13

Lubrication

5-2
Α&Β Oscillator and Control

2-14

V isual
Inspection

5-2
1st LO/1st L O L ock

2-15

Transistor and I ntegrated
Reference L evel, R eadout, and

Circuit Checks

5-2
Timeslot

2-15

Troubleshooting

5-2
R eadoutand Timeslot Decode

2-18

Troubleshooting
Aids

5-2
IF Processing Chain

2-19

Finding F aulty
Semiconductors

5-3
V ariable R esolution

2-20

General Troubleshooting
10
kHz &
30
kHz F
ilters and

Techniques

5-5
P ost VR Amplifier

2-22

Corrective M
aintenance

5-5
L og/Lin Amplifier

2-22

Disassembly of the 7L5 and
Detector and Video Amplifier

2-22

Replacing Assemblies

5-7
Display Processing

2-23

Removing the Front P anel

5-7
H orizontal and Vertical Display
Removing the IF Module
Processing

2-23

Assembly

5-7
Average Calculator (SN Β 069999

R emoving the
Sweep Board

5-8
and below)

2-24

Removing the RF Module

5-9
Digital
Storage (SN Β 069999

Reassembling the 71-5

5-9
and below)

2-25
Digital Storage
and Averaging

Internal Operational Adjustments

5-9
(SN Β 070000and
up)

2-30

SECTION 6

OPTION INFORMATION
S ECTION 3

PERFORMANCE C HECK
REV . Α ΜΑΥ 197 8
TA BLE O F CO N T EN TS
Introduction

3-1

SECTION
7

REPLACEABLE ELECTRICAL
Equipment Required
o
r

PARTS
R ecommended

3-1
1 . Sweep Triggering

3-2

SECTION 8

DIAGRAMS AND
CIRCUIT
2 . Dot Frequency Range and

BOARD ILLUSTRATIONS
Accuracy

3-2
3 . Display F latness

3-3

SECTION 9

REPLACEABLE MECHANICAL
4 . Frequency Span Accuracy &

PARTS
AND EXPLODED
L inearity

3-4

DRAWINGS
5 . Sweep Rate Accuracy

3-5

CHANGE INFORMATION
6 . Intermodulation Distortion

3-6
7 . Display
Frequency Stability

3-7
71-5 Service

F ig . 1-1
. 71-5 Sp ect r u m Analyze r .
REV Α , ΜΑΥ 1978

G
ENER A L I
NF O RM ATIO N
I N T R OD U CTIO N A N D D E SC R I P TIO N

To accommo d ate α wi d e variety of
im p
eda
n
ce so ur ces,
To effectively use t h
e
71-5
Spect r um A n alyzer, t h e

the 71-5
uses q uic k disconnect
p
lug-in
i npu t im p e d a n ce
op eratio n
and ca p abilities of t h e instrume n t m u st be

mo
d ules of 50 Ω , 75 Ω , 600 Ω , 1 ΜΩ /28 p F and customiz-
kn ow n . T h is instructio n ma nu al
covers ge n eral se r vice

ed
u nits to meet s p ecial re qu ireme n ts .
i n formation for t h e i n strume n t . It contai n s t h es
p ecifica-
tion, test an d cali b ratio n procedure, circ u it descriptio n ,

When t h e 71_5's digital storage ca p ab ility is em p loye d ,
a n d mai n
te
n
ance p rocedu r e fo r t h e 71-5 .
one or
two
com
p lete
dis p
lays ca n b e h eld in memory for
subsequent viewi n g, com p ariso n , or grap h ic r e pr o d uc-
T h e 71-5 is α 5 MH z spectrum an alyzer wit
h d igital

tion . T h is capability co n verts α n o n storage, 7000-Se r ies
sto r age . Fr eque n cy stability is wit h i n 5H z/ h r and center

oscilloscope d isplay into α stored dis p lay . T he small d ot
fre q uency (dot) ca n be r ea d wit h six d igit
accuracy

size (of t h e conve n tional oscillosco p e) used wit h t he 7 Ι -5
imme d iately after
turn-on ; t h erefore t h ere is no n ee d to

e nh a n ces t h e resol u tio n of low am p litu d e sig n als an d
fi ne tu n e t h e
dis p lay . Com p lex measu r eme n ts an d
ot
h er fi n
e d
etails t h at are often lost wit h α variable
a n alysis ca n be made wit hrelative
ease . B uilt-in

p
ersistence oscillosco p
e .
In
storage mo d e, t h e vertical
micro p rocessi n g circuits d eco d e co n trol setti n gs, p
rocess

dis p lay m ay be bisected byan averagi n g t h res h old, a b ove
freque n cy a n d refere n ce level i n formatio n ,
a
n
d o p timize

w h ic h vi d eo p ea k d etectio n occurs (p r ior to storage) and
swee p time a n d resolutio n for t h e selecte d f r equency

below w h ic h vi d eo signal averagi n g occurs ( p rior to
s p a n . At
turn-on,
t h
e 71-5 is p reset to α refe r en ce level of

storage) . De n ote d by α cursor, t h e ave r aging t h res h old is
+17 d B m (50 Ω in p ut) a nd ce n ter fre
q ue n cy of 00 .0 kH z .

co n ti n uo u sly a dj ustable wit h α f r o n t p an el co n t r ol . T he
T h is provides i n put atte n uation to pr otect t h e fro n t-e n
d

storage circ u itry inclu d es α maximum h ol d capability .
circuitry a n dα mar k er to verify correct ope r ation .

T h is feature allows mo n ito r i n g of sig n als t h at may c h a n ge
wit h time to p rovi d eαgra ph ic r ecor d of amplitu d e/f r e-
T h e 71-5 wit h 80 d B
or more of s p urious free dy n amic

q
ue
n
cy excu
r
sio n .
ra n ge p rovides t h e ability
to measure wide relative
amplitu d es . N a n ovolt se n sitivity provides ve r y
low-level
signal
a n d noise requireme n ts .
T h e 71-5 dis p lay is fully calibrated in dBm, dBV,
or
volts/div . T h
e
reference
level ca n be accurately set i n 1 dB
i n creme n ts .
Α front p a n el i np ut buffer co n t r
ol
i n
creases
fro n
t-end
imm un ity to intermod u latio n d istortio n w h ile mai n tai n i n g
αconsta n
t reference level .
W A RN I NG
7L 5 Service
T he following se r vice i n structions are for p e r so nn el
qu alified
to
se r vice elect ronic circuits . P ersonnel n
ot
familiar wit h elect r ical ci r cuit op eratio n s hou ld n ot
p e r fo r m an y se r vice ot h er t h a n t h at
co
n taine d
in
t h e
Operating I n stuctio n ma n ual .

Gene r al I n fo r matio n - 7 L 5 Service
M A
NU
A L
O R GA N IZATIO N A N D

Sectio n
8-Diagrams : Fu n ctio n al bloc k diagrams and
CO
N T
EN T

d etaile d circuit
sc
h
ematics are p rovided . L ocate da dj a-
ce n t to t h ed iagram (usually on t h e bac k
of
t h epreceding
d iagram) are p ictorial layo u t drawings t h at s h ow sub-
T h e abbreviations, grap h
ic symbols, and logic sym-

assem b ly an d com p onent locatio n s . I n tegrate d circ u it
bology u
sed i n t h e text a n d diagrams of t h
is manual are in

d iagrams,

wavefo r ms

a n d

voltage

data

for
accord wit h a n
d based on A N SI Υ 1 .1-1972, A N SI Υ
32 .3-

troubles h ooting
or
ci r
cuit an alysis are also p r ovi d e d
1975, a nd A N SI Υ 32 .14-1973
(America n N atio n al Sta n dar d

ad j ace n t to or on t h e diagram .
I
n stitute, 345 E ast 47 Street ; N ew
Yor k
,
Ν
.
Υ
.
10017) .
C
h
a n ge information is co n tai n ed on i n sert p
ages att h e
bac k
of
t h e
ma nu al . Origi n al p ages are i d e n tifie d by t h e
sy mb ol @ a nd
revise d p ages a r e i d entifed by α revisio n
d ate i n t h e lowe r i n
si d e cor ne r of t he page . If t h e se r ial
n um b er of your instr u me n t is
lowe
r
th an t h e o n e on t h e
title
p age, t h e man u al con tai n s r evisio ns t h
at may not
apply to yo ur i n
strume n t . H istory i n fo r matio n , a p plicable
to p revio u s pro d ucts, wit h
t
h
e u p date d d ata, is integ r ate d
w h en t h e p age
or d iagram is revised . T h e followi n g
d esc r i b es t h e sectio n s a nd i n
fo
r
matio n provi d e d in t h is
m a n ual .
Sectio n 1-Ge n eral I nformation :
Co
n tai n
s
t h
e
i n
st ru
-
m en t d escri p tio n a nd specification .
Sectio n 2-Ci r cuit Descri p tio n : P rovi d es b asic and
ge n eral circ u it t h eory . T h is i n fo r matio n may be u sef u l
w h en se r vici n gor
o p erati
n g
t
h
e
i
n strument .
Sectio n 3- Pe r forma n ce C h ec k : P rocedu res to verify
t h at t h e i n str u me n t is p erformi n g wit h i n its sp ecifie d
limits .
Sectio n 4-Calibratio n Proce d ure : Test equ ipme n t
set up a n d ad ju stme n t p rocedures r e q uire d to calibrate t h
e
i n st r ument .
Sectio n 5- M ai n tena n ce : Descri bes
ro
u ti n
e a
n
d cor-

Accuracy
rective maintena n ce procedures wit h d etailed i n st r uctio n s
for r eplaci n g assemblies, s ub -assemblies, or i nd ivi du al

20°C to 30°C
: ±(5 Hz + 2χ10 -6 of d ot r eadout) .
com p o n ents . An
ex
p
loded dr awing is pa r t of Section 9 .
Troubles h ooting p roced u res p l us general i n
formatio n
0°C to 50°C : ±(20Hz + 10 -5 of d
ot
r
eado u t) .
t h at may ai d i n servici n g t h e i n st r ument are also
pr ovided .
Sectio n 6-Options
Informatio n : Describes optio n s to
t h e i n st ru me n t or directs t h e reader to w h ere t h e
o p
tio n
s
are d oc u me n ted .
Sectio n 7- Replaceable E
lectrical P arts : P rovi des in-

50 Ητ /d iv to 2 kH z/ d iv : 1 H z
(p-p) or less .
formatio n n ecessary to o rd er re p
laceable parts a n d
assemblies .

5 kH
z/ d iv to 500 kH z/ d iv : 40 Hz (p-p) or less .
Sectio n 9- Rep laceable M ec ha n ical P arts, E xplo ded
D r awings a n
d
Accessories
:
P rovi d es info r matio n
n ecessa r y to ord e r re p laceable parts . T h e Re p lacea b le
P arts list is c r oss- r efere n ced to t h eR ep lacea b le E lect r ical
P arts list . T h e explode d drawing i d e n tifies assemblies a n d
m ech a n ical com p o n e n ts .
C h
a
n
ge
I n
formation : P rovi d es up dati n g info r matio n in
t h e form
of
i n
serts for t h e ma n ual . T h ese i n serts are later
i n cor p orate d i n to t h e ma nu
al text and d iagrams w h en t h e
ma n ual is r epri n ted .
ELE CT R ICA L CHA R ACT ER
ISTICS
T h e followi n g
elect r ical c h aracterstics apply w h e n th e
71_5 S p ectr u m A n alyzer, i n
combinatio n wit h a Plug-in
M odule, are n ormally i n stalled i n α 7000-Series
os-
cillosco p e a n d after α warm-up of ten mi nu
tes or more .
Fr e q ue n cy
Characteristics
R ange
I np ut F re que n cy : 10 Hz t hr oug h 5 .0 MHz .
Dot F reque n cy : 0 H z t h
ro
u gh
4999 .75
kHz
.
Drift
5 Hz/hour o r less .
Residual (inci den tal) FM

R
esolution B a
n
dwidt h Amplitude C ha r acteristics
Acc u racy
NOTE
30 kH z-30 Hz : Within 20% of selected resolution
(6 dB dow n ) .

If digital storage is use d , an additional quantization
e rr o r of 0 .5 ο/ο of full sc r een s h oul d be a dd e d to t h e
10 H z : W it h i n 100 H z ±20 Hz (70
d B down) .

amplitude c
ha r
acte
r istics .
T h e CO UPLE D setti n g electronically selects
t he best resolution b a nd widt h fo r eac h setti n g of
t he FRE Q UEN CY SP AN /DI V co n trol .
S h ape F actor
30
kH
z-3 kH z : 5 :1 o r b ette r (60 :6 dB ratio) .
1 kH z-10 Hz : 10 :1 o r b ette r (60 :6 dB ratio) .
Amplitu d e Deviatio n
30 kH z-100 Hz : 0 .5 dB or less .
30 kH z-10 Hz : 2 .0 dB o r less .
Input
C
ha r acteristics
CA U TIO N
The
application of αdo voltage to t h e I NPU T of t h e
L 1 or L 2
Plug-In
M od ules
may cause p ermane
n
t
damage to t h e mixe r circuit .
I n put Impe d ance
(
N omi n al) :
L 1

50 Ω
L2 75 - 0
L
3

Selectable (50 Ω , 600 Ω , an d 1 ΜΩ /28 pF) .
R esi d ual R esponse
I n
te
rn ally ge n erate d spurious signals are-130 dB m
o r less r eferred to t h e i nput ( h armonics of t h e calib r ato r
are -125 d B m) wit h L 1 o r L2 p l u g-in mo dule an d
-143 d BV wit h t he L 3 p l u g-i n mo du le .
Se n sitivity
General
I n formatio n -71-5 Service
Th e followi n g tabulatio n of eq uivale n t in p ut
n
oise
fo r eac h resolutio
nban dwidt h
is meas
ured wit h ; t h e
I NPU T BUFFER off, t
h
e
V
ID
E O ΡΕΑΚ
/A
VG
at
max cw,
a nd t he ΤΙΜΕ /DI V set to 10 seco nds .
Eq uivale n t I np ut N oise
R esol u tio n (e q ual to o r better t ha n )
B a nd wi d t h L 1 L2L 3
10 Hz

-135 dB m

- l 35 dB m
30 Hz

-133 dB m

-133 dB m
100 H z

-130 d B m

-130 dB
m
300 Hz

-125 dB m

-125dB m
1 kH z

-120 dB m

-120dB m
3 kH z

-115 d B m

-115dB m
10 kH z

- l 10 d B m

-110dB m
30 kH z

-105 dB
m

-105 d
B m
ΝΟΤΕ
- l 48 d BV
-146 d BV
-143
d
BV
-138 d BV
-133 d BV
-128 d BV
-123
dBV
-118 dBV
Se n sitivity is deg r a d edan additional 8 dB w h en t h e
I NPU T BUFFER is on ; e .g ., at 3 kH z, t h e equivale
n t
input

noise

wo u ld

be

-107 d Bm

instea d of
-115 dBm .

N oise level will inc r ease by ap-
proximately 10 dB w h en operation is in vi d eo pea k
mode .
L 1

21 d
B m o r 2 .5 V r ms
L 2

21 dB m
or 3 .07 V rms
L 3

21 d B m-i npu t te r min ate d 50 Ω
or 600
Ω ;

Intermodulatio n Disto r tio n
100 V ( peak ac + d c) i nput 1 ΜΩ /28 pF .
I ntermodulation pr o du cts f r om two on-screen
Inpu t P owe r (maximum i np ut level for refere nce levels
of 0 dB m o r greater) :
sig n als, wit h i n any frequency sp a
n are >75
dB
d ow n
I n put P owe r (maximum i n
put level fo r refere nce levels

for
t h ir
d o
r
der p ro
du cts and at least 72 dB d ow n fo r
b elow 0 d Bm) :

seco nd o rd er p r oducts .
L 1

+10
dB
m
L 2

+10
d
Bm

Seco nd and t h i r d or d er intermodulatio n p ro d ucts
L 3

+10 d Bm -i np ut termi nated 50 Ω
o r 600 Ω ,

from two
on-screen
-53 dBV or less sig n als wit h i n any
and 100 V (pea k ac + dc) wit h i np ut of 1 ΜΩ /28
pF
.

freq uency spa n a r e at least 80 dB d ow n .

Gene r al Informatio n -71- 5 Service
W it h t he
I
NPU
T BUFFER switc h on, t he t h ird order

Sweep C h aracte r istics
i n termo d ulatio n pro d ucts, for any two on-screen

Freque ncy S pan . P rovides calibrated frequency spans
sig n als, wit h i n any fre q uency span , a r e at least 80 dB
from 50 Ητ /div to maximum 500 kH z/ d iv, wit h i n 4 ο / ο , i n 1-2-
dow n .

5 se q uence .
Dis p lay F lat n ess
P eak to p
eak deviatio n , over any selected fre q ue
ncy
sp an : Qua
n tizatio n error must be a dd e d (see
N ote un der
Am p litu d e C h aracteristics) if d igital
storage is use d .
H orizontal linearity is wit h i n 4 ο/ο
over
t h
ee
n tire
10
div
d isplay .
L 1

0 .5 dB ;

Α 0- H z/Div p ositio n is p rovi d ed for time d omain
L 2

0 .5
dB ;

operation .
L3

0 .5 dB ;
R efere nce L evel

Swee pR ate . Time per div is selecta b le from 10 s/ d iv to
0 .1
ms/div i n
α
1-2-5
seque
nce . An
AU TO p ositio n permits
R efers to to p g r aticule li
ne i n L
og
mode . Cali b rated i n
automatic selection
of o p
timum time/ d iv for t he selecte d
1 d B a nd 10 dB
ste ps
for
t he L 1 a nd L2 modules a nd

r esolution an d spa n / d iv .
1
d
B /2 dB a nd 10 dB for L 3 p lug-in module .
R a n ge L 1
L2L 3
L og

-128 d
B m

-128 dBm/

-128 dB m to
2 d B /Div

to
+21 dB m

139 d BV to

+21 dB m (50
Ω ),
Triggeri
ng .
Provides twotriggering so
urces, 1 Ν 7 (inter-
+21 d B m/

-139 dB m to

ηα
1)
and
L
I
NE, i n a dd itio n to α FREE-RUN position .
+10dBV

+10 d B m (600 Ω ),
-141 dBV to

When ΙΝΤ is selected, ac cou p led
sig n al com p
o
nen
ts
+8 dBV (
H i Ζ )

from t h e mainframe
Trigge r Source (left or rig h t vertical
L og

-70 d Bm

-70 d B m/

-70 d B m to

am p lifie r s) a r e u sed .
10 dB /Div to +21 d B m

-81 d
BV to

+21 dB m (50 Ω ),
+21 d B m/

-81 d B m to
+10 d BV

+10 dB m (600
Ω ),

Wh en
L I
NE is
selecte d , ac cou p led sam p le of main
-83
dBV
to

frame line
voltage
is
use d .
+8 d BV ( H i Ζ )
Incremental
Accuracy
Wh e n calibrated at -40 d BV in
L
og
mode :
L 1, L 2 an d
L
3 :Within
0 .2d B /d B wit h c u mulative error of
0 .25 d B /10
dB .
L i n M od e Ra n ge : 20 m V /Divto 200
mV /Div wit h in 5 ο/ο i n
1-2-5 se q uence .
ΝΟΤΕ
Α >s ί gn is dis p laye dad jacent to t h e r efe
r
ence level
r eadout wh en t h e refe r ence level is not calib
r
ate d
due to an incompatible selection of co
n t r ols .
Disp lay Dy n amic R an ge/Accu r acy
Swee p rate accuracy is wit
h
in 5 ο/ο of
t he rate selecte d .
T h ree triggeri ng modes are ;
N
O
RM
(normal), SG L
S WP / RE ADY (si n gle sweep), an d MNL S WEEP (ma nu al
swee p ) .
Trigger level is >1 .0 d iv of i n ternal sig n al for bot h
N
O
RM and SG L S WP modes over t h e a pp roximate
fre que
n
cy
range
of 30 Hz to
500 kH z .
Out p ut Co n nectors
V
ideo Out
. F ro n t-panel pi n j ac k conn ector sup p lies t he
vi deo (vertical) out pu t sig n al at an amplitude of 50 mV / d iv
±5 ο/ο (about t he c rt vertical cen ter) wit h sou rce impe d ance
of 1 k Ω .
L og 10 dB /Div M ode : Dynamic wi nd ow is 80 dB .
Acc u racy is
wit h i n 0
.05 d
B
/d
B
to
2 dB maximum .

H oriz Out . Α front-panel pi n j ack conn ecto r s upp lies
h orizontal output signal ( n egative-goi n g sawtoot h t h at
L og 2 d B /Div M ode : Dynamic wind ow is 16 d B . Ac-

varies from 0 .0 V d o to approximately -6 V dc) wit h α
curacy is
wit h in
0 .1 dB / dB to 1 d B maximum .

source im p ed ance of 5 k Ω .
REV . Α ΜΑΥ 1978

Calibrator . F ro n t panel BNC co
nn ector s u pplies α

I N
STA LL ATIO N
cali
b rate d 500 kH z s q uarewave
o u tput sig n al ( d e r
ive d
from t he an alyzer's
time b ase) . Out pu t am p lit ude is
wit h i n
±0 .15 dB of -40 d
BV i n to t he im ped a nce of
t he p lug-i n

I n itial I nsp ectio n
mo d ule .

Th is i n strume n t was i n s p ecte
d both mec h a n ically and
electrically before sh
ipment . It should be f r ee of
mars o r
En
vi r
on
mental C h aracteristics

scratc hes a nd
elect r ically meet or exceed
t h e s p ecifica-
T he 71_5 S p ect r um
A n alyzer will meet t h e
foregoi n g

tio n . I nspect
t h e i n strume n t fo r ph ysical
damage an d
electrical ch aracte
r istics wit h in t he enviro
n me n tal limits

chec k t he
electrical p erfo r mance
b y t h e O p e r atio n al
of α 7000-Se
r ies oscillosco pe . Com
p lete details on en -

C
heck procedure p rovided
wit h i n t he O pe r ators I n struc-
vironmental
test proce d ures, i n clu
d ing failure criteria etc .,

tio n Manual . T h is proce
dur e will ve r ify t h at t he
i n str u me n t
can b e
o b tained from α local
Te k tronix F iel d Office or

is op erati ng co
r rectly an d it will satisfy
most r eceivi n g or
re p
rese n tative .

incomi ng
i nspection re q uireme n ts .
If t h e instr u me n t
s p ecification
is to b e ve r ified, refer to
t h eP erforma nce
C
heck p roced u re i n t h is
man u al .
Ph ysical C
ha r acte r istics
N et weig h t (i n str u
me n t only) : 8 pou n ds, 12 oun
ces .
ACC E SSO
R I E S A N D O P TIO N S
R efer to t he R e p lacea b le
M
ech
a n ical P arts L ist for α
com p lete listi n g of t he stan
d ard an d op tional accessories
.
Options
Ge n
eral Information-71-5
Service
If t h ere is p h ysical d
amage or p erforma n ce d
eficie n cy,
co n tact your local Te
k tro n ix F ield Office or
r e p rese n -
tative .
71_5 O p tion
21-( L og Dis p lay)
71_5 Optio n 25-(Trac k i ng Ge n e r ator)

Installatio n
71_5 O p tion 28-( R ead o u t)

Install i n α
7000-Series main frame an d afte r α 10 mi
nu te
71_5 Optio n 30-(O p tio n 21/25)

or more warm-up,
ch eck p erfo r ma nce . To
cali b rate or
71_5Option 31-(Optio
n 21/28)

service t h e
71-5, co nn ect it to t he 7000-Se
r
ies
mai n fr ame
71_5Option 32-(Optio
n 25/28)

i n terface
t hroug h flexible p lug-i n exten
d ers (see Eq ui p-
71_5 O p tio
n 33-(Optio ns 21/25/28)

me
n t R equire d ; Calibratio n sectio
n ) .
REV . Α
ΜΑΥ 1978

Gene r al I nfo r mation-71-5
Service
REP AC K AGI N G F O R S H I PMEN T
If you r Te k tronix i n st ru
me
n
t is to b e s h i ppe d to α
Te k tro n ix Se r vice Ce n ter for service
or re p laceme n t
attac h α tag s h owi n g ; ow n er (wit h add r ess) an d t h e n
ame
of
an
i n
divi du al at your firm t hatca n be contacted . Include
com p lete i n strume n t
serial
n
um b er a n dα d escriptio n of
t h e service r e q uired .
Save a
n
d re- u se t h e p ac k age you r instrume n t was

G r oss W eig h t (Ib)
s h i pp ed i n . If t h e origi n
al pac k agi n g is n ot available or is
u n fit for use, repac k age as follows :

0-10
10-30
1. O b tai n αsh i pp i n g co n tai n er of h eavy co r r u gate d
30-120
ca rdb oard or woo d wit h i n si d e d ime n sio n s at least
six

120-140
i n c h
es g
r
eater t h an t he i n st r ume n t d ime n sio n s . T h is will

140-160
allow r oom for cus h io n ing . R efer to
Table 1-1 for carto n
test stre n gt h re qu ireme n ts .
2 . Wr a p t h e i n strument i n h eavy pap e r o r p olyet h ylene
s h eeti n g
to protect t h e inst ru me n t fi n is h . P rotect t h e fro n t
p a n el wit h u r et h ane foam or car d
boar d strips .
3 . Cus h io n t he i n str u me n t on all
sides b yp ac k i ng
dunn
age o r u ret h ane foam betwee n t h e ca r to n and t h
e
i n strume n t, allowi n g t h
ree inc h es on all si d es .
4 . Seal t he s h i p pi n g carto n wit h s h i pp i n g
ta p e or an
industrial sta p le r .
TA BLE 1-1
Ca
r
to
nTest
St r e n gt h (l b )
200
275
375
500
600
If
you
h aveany qu
estio
n
s, co
n
tact your local Te k tronix
F ield Office o r r e p rese n tative .

CI R C U IT D E SC
R I P
TIO N
Section 2-71-5
Service
Int r od uction

T h e video sig n al is t h en fed to t
he display processi ng
T he 71_5 is α swept fr o n t-en d spect
r
um
an alyzer wit h
circ u its w h ere t h e sig n al is eit h er store d a nd dis p laye d , or
selecta b le f r o n
t-e ndp lug-in mod u les t h at permit t he use r
if t he storage mo d e is n ot selected, t he sig n al is p assed
to o
b tai nα cali b rate d display fo r α number of d ifferent

directly t h ro u gh t he vertical o u t pu t amplifier to
t h e
impeda nce (i .e ., 50 ohm, 600 o hm, etc .) .
T hep
lug-in

mai n frame circ u it . If eit her or both
t he DIS PL AY Α or
mod u le co n tai ns : selecta b le atte
nu atio n , t he fi r st mixer,

DIS PL AY Β latc hes are e n abled, t h e signal is co nve r ted to
i np ut low-pass
filter,
a
nd
an
input bu ffer selector t h at

d igital d ata, store d in Α or Β memory, t h enco n verte d bac k
trades
noise figu r e fo r ΙΜ p e r forma nce . Signal atte nu atio n
to

an alog

data

an d

p r ocessed

t h ro u g h

t he out p ut
in
t he
p
lug-in a nd gain of t h e I F p r ocessi n g ch ain are

am p lifiers to t h e circuit . T he vertical info r matio
n
is
co n tr olle d by α refe r ence level logic ci r cuit
i n t he 71_5

d igitize dand sto r ed at 512 h orizontal address
locatio ns
w h ic hp rovides calibrate d
settings i n 1 dB or 10 d B steps

across t h e screen
.
T herefo r e, t h e h o
r
izo
n
tal
sweep infor-
over α range of
149 dB .

matio n is co n verted to d igital data fo r sto
r
age,
t hen
co n verte d bac k to an a n alog
sig n al for d is p lay . T he
F
unctional B loc k Diagram

h
orizontal swee p ramp is
processed t h e same as t he
vertical signal . T he vertical (video) i n fo r mation can b e
T he in p ut sig n al to t
he 71_5
is
mixed wit h t he fre q ue n cy

averaged o r p ea k d etecte d .
of t h e mai n oscillato
r an d fed to t he I F at 10 .7 MH z an d
amplified byt
h e10 .7 MH z I F amplifier . Since the 71_5 input
freque n cy range is 0 to 5 MHz, t h e main oscillato
r
is
t u ne d
and swept from 10 .7 to 15 .7
MHz . T he f r equ ency of t he

I F Pr ocessi ng C h ai n
1O b
mai n oscillato
r
is
controlled b y two seco ndary ( Α an dΒ )
oscillators
t h at u se α syn t h esizer tec hn i qu e to t u ne a
n
d

Th is bloc k diagram s h ows mo r e d etail of t h e circ u itry
p h ase loc k t h ei r f r e qu encies . T h e swee p fre q
uency co n -

i n volve d wit h processi ng t h e I F sig n al from t
he 1st m ixer .
trol ci r cuit drives t he oscillators acco
rd i n g to t h e setti n gs

Sig n al loss t h roug h t he 1st mixer is abo u
t 9 dB . T he I F
of fro n t pan el DOT
FRE
Q
UEN CY and FRE Q UEN CY

outp ut of 10 .7 MHz passes
t hroug han i np ut a nd 30 kH z
SP AN /DI V co
n trols
.

filter to im
p rove flat n ess, t h en α 30 kH z crystal filte r
s h apes t he r es po nse to t h e ba nd pass c h aracteristics of t he
T he sig n al at 10 .7 MHz is p r ocesse d t hr oug hαb a n d-

i n strume n t . Α -40 d Bm sig n al is r e q uire
d
at
t h
is
point for
pass filter a nd am p lifie r , t h e n mixe d wit h t he o u tp u t from α

full sc r ee n deflection .
10 .450 oscillato r to d own-convert t h e 10 .7
MH
z to an
I F
of
250 kH z . Gain of
t he
250
kH z
am
p lifier is
co
n t r olled
by
t he
r
efere
nce level logic circuit w h ic h esta b lis hes t he amou n t
of atte n uatio n i n t he pl u g-in mo du le an d gai n fo r t he

Sign al level is increase d 20 dB by t he 10 .7 MHz I F
250 kH z I Fa nd L og am p lifiers . T h e reference level is

a m plifier ; it is t hen fe d through t h e300 kH zba nd passfilter
selectable in 1 dB an d10 dB ste ps .

to t he 2 nd mixer . T he 2n d L O fre q ue ncy of 10 .450 MHz
mixi
ng wit h10 .7 MHz pr oduces an
I F
of
250 kH z w h ic h is
T he 250 kH z I F sig n al is processe d t hr oug h t h e variable

fed t hroug h α 500 kH z low p ass filter to t he 250 kH z
resolutio n filter ci r cu its fo r ba nd wi d t h selectio ns of 10 Hz

amplifie r . T h e loss t h roug h t he 350 kH za nd 500 kH z filters
to 30 kH z . T he sig n al is again am p
lifie
d , d etecte d , a nd t
h
e

plus t h e 2 nd mixer is abo u t 10 dB ; t h us α -30 dB
m sig n al
vi d
eo is sen
t t h
ro
ugh am p lifier circuits t h at p rovide t h e

level
is re qu ired at
t he inp u t of t h e 250 kH z am p lifier to
10 d B /div, 2 dB /div, a nd li nea r gai n c h aracteristics .

o b tai n f u ll screen d eflection .

Circuit Desc r i p tio n -71- 5 Service
T h e 2nd L O fre q uency is con t r olle d by α p h ase loc k resolutio n t h at is n ot a pp ro p riate for t he FRE Q UEN CY
loop w h ic h uses 50 kH z a nd 100 kH z subm u lti p les of α

SP A N selected, t h eR OM activates α CA L lig h t to in-
master 10 MH z c r ystal co n trolled oscillator to
drive

vali d ate t he reference level readi ng an d t he rea d out
500 kH z a nd 100 kH z refere nce f r eq uen cies .
T he gai n of

presen ts α < symbol i n fro n t of t he refere nce level rea d out .
t he 250 kH z I F amplifier is co
n trolled b y t he decoded
out p ut from t h e refe
r
en
ce level counter . T h e r efere n ce

The out p ut sig n al from t h e
R
esolution
F ilters is fe d
level
cou
n te r i n turn, is co n trolled by t he f r on t pa n el

t h roug hα
P
ost
VR Am p lifiert h e nα L
og/
L i n amplifier . T he
REFEREN C E LEVEL control . Gai n of t h e am
p lifier is

respon se am p litude level is now eit h er L og 10, L og 2, or
a dj ustable i n 1, 2, 4, 8, a
nd two 16 d B ste ps . T h e

Li n ear d epend i ng on t h e setti ng of t h e log/li n latc hes .
atte n uators,
i n
t
he
p
lug-i n mo d ule a r e 4 d B, 8 dB, and

These latc h es are activated by fro n t p a n el momentary
32
dB
. Combinatio ns of attenuators a nd I F gain are

contact p us hb utto ns . Log 10 control is also fed to t he I F
selected by t h e refere nce level cou n ter a nd provide gai
n
Gain an d RF Atte n uatio n Deco d er .
c h anges of 1 dB or 10 dB ste
p
s,
d e p end i n g
on
t he p ositio n
of t he
REFEREN
C
E LEVEL control . T he crossover poi n t
(no
atte n uatio n a nd unity gai n t hroug h t he am p lifier) is

T he I F is t hen d etecte d and
t he ou tp u t video sig n al fed
-30 d Bm .

to
an
ot
he r L og/ L in amplifier for gai n ad j ustme n t betwee n
t he L og/ L i n d is p lays . P art of t h eo u t p ut is fe d to U 2005 to
p rovide push-pull trigge r
sig n
als (+ an d -) to
t h e main-
T h e REFEREN C
E LEVEL co n trol is α p ri n te d circuit

frame and vi d eo sig
n
als to
t he V ID E OOU T j ack on t he
switc h t h at outp uts α
two bit bi n ary code t h at re p eats every

fro n
t p
a
n el . T he mai n vi d eo signal is fed to t he d isplay
four
times
.
T he co de indicates t he d i r ectio n t he co n trol is

p
rocessi ng circuits w here it is p rocessed eit he r t hroug h
rotate d a nd an IC d etermines w h et h er t h e cou n t is up or

amplifiers to t h e mai n frame for display, or, if t he 71_5 is
dow n . T he output code of t h e co n trol, cloc ks αco un ter

op erati ng in t he store mo d e, t he sig n al is sto r ed i n
w h ic h p rovi d es t h e refe r ence
level
re q
uired
to
d rive t h e

memory, a n d t hen dis played as t h e memory is
r
efres
hed or
rea dout . Analog cu
rrents areprovided by α R O M w h ic h is

up d ate d .
rea d i n g t he out p ut of t he cou n ter . Wh en t h e REFEREN C E
LEVEL control is pu lle d out, for 10 dB ste p s, t h e cou
n ter

Sweep Co
n trol
a
nd F re q ue n cy R efere n ce

Ο α
coun ts i n te ns i nstead of d igits . Wh en
L I N
mode
isselected
or t he dBm/ dBV switc
hon t he plug-i n module is ch anged,

T h e Sweep Control circuit uses an IC t h at features ;
t herea
do u t cha n ges t he R efere nce L evel Cou n ter so t he

swee p gati n g, brig h t baseli n e, h oldoff
timi n g,
a u
tomatic
crt refere nce level readout is i n V olts/Div or dBV . T h evalue

free run, loc k out, single sweep and si n gle swee p rea d y
of t he constant to t he co un ter de p ends on
t h e i nput

lig h t co n trol . The gate sig n al d rives t h e sweep generator
impeda
nce
of
t h e plug-in mod u le . T h is establis h es α

w h ic h i n t u r n sends α swee p t hroug h t he Manual Swee p
calib r atio n refere n ce level comme n surate wit h t he respec-

switc h to t he Display P rocessi n g a nd ci r cu itry relate d to
tive i np ut im p edance of t h e "L" p lug-i n module .

t he swee p fo r t h e Α a nd Β oscillators . I n puts to t he swee p
co n trol IC i n cl ude triggeri n g source a nd mo d e signals .
Trigger
mo
d
es
are set b y latc hes t h at areactuated by f r ont
T h e i np uts to t he I F Gai n a nd RF Atte nu ation Deco d
i n g

panel mome n tary contact push b u tto n switc h es .
b loc k are t h eo u t pu t from
t he R
efere
nce L evel Cou n te r
a n d
t he L
og 10 or
L og 2 switc h latc h es . T he o u t pu t

WhenSG
LS WP is selecte d , t h e swee p is loc k ed out
supplies
fo ur gain ch ange li n es to t he I F am p lifie r a nd t he

u n til t he SG L S WP b utton is p us hed agai n . T h e circuit is
atte nuato r codes for t he pl u g-i n module . An i n vali d code is

now a r med and t h e swee p will run if t he
trigger
source
is
fed b ack to stop t he co un ter w hen t he refere nce level

FREE RUN or w h e nα triggersignal
arrives . Α built i n d elay
r eac hes α lower limit .

of a pproximately 10 seco
nd s allows t h e sweep to run if no
trigger arrives ( n ot i n 0 H z spa n ) . T h is k eeps t he memory
ca p acitors for ph ase loc k loop, of t he Α a n d Β oscillators,
T he out p ut of t h e 250 kH z I F is fed to t h e V ariable

r efres hed .
R esol u tio n F ilter . B andwi d t h s of 10 Hz to 3 kH z are
selected by one filter b loc k and 10
kH z a nd 30 kH z
bandwidt hs b y α seco nd bloc k .
Sign al r
o
u ti ng t hrough t he
Wh
e n MNL S WP is selected t he Swee p Generator is
filters, is
controlle d by t h e resolution code w h ic h i n tur n

u sed as α 100 seco nd timer to refres h t he memory
may b e cont r olled b y t he RE SO LU TIO N co n t r ol . F or

capacitors . T he Swee p Co n
trol allows t h e Swee p
au tomatic o r coup led o p eration, αR OM selects t h e

Ge
ne r
ato
r
to free r
un ; h owever, t h e Manual Swee p switc h
a pp ro p riate resol u tio n b a n dwidt
h
so
t h e b a nd wi d t h an d

now
selects t h e voltage output of t h e LEVEL /SL O PE
f r eq uency s pa
n are compatible . If t he op erator selects α

co n trol for t h e Swee p H orizo n tal sig n al .

Circuit Description- 7L5 Service
When t he
sweep mode is N ORM, sweep operation is

voltage of zero . The time shared
dot position is therefore,
conventional . The LEVEL/SLOPE control selects the

derived
froman equivalent sweep voltage of zero . Fre-
triggering level and slope unless the mode is
MNL
S
WP . It

q uency of the d ot position is displayed by the crt readout .
then becomes α manual sweep
control .

Accurate frequency measurements can be p erformed by
tuning any d esired segment of the d isplay under
the
frequency d ot and read out on the
crt .
In
most cases
The sweep generator contains an
end of sweep com-

readout
accuracy is <1°/ ο of the d isplay span or within
p arator that outputs α pulse
which is fed back to the sweep

±50 H z .
control IC to
terminate the output gate and i nhibit the
sweep .
The end
of
sweep pulse is OR'd with an output line
from
the phase lock logic circuit, which goes
h igh
at
the

In all frequencyspan positions
except
MAX
s p an, the
end of the gate pulse period a nd holds
this state until the

frequency dot is at
the center or start of the display . In
sweep c ontrol circuit
h
as
stabilized about (50 ms) then it

MAX
span the center frequency of the span is 2 .5 MHz .
pulls the
R
eady
line low . The state of the Ι a nd Sense lines,

The frequency d ot moves across the display as the center
from
the d ot frequency control and p hase lock loop
circuit

frequency is tuned . The fre q uency readout accuracy of
must also be correct beforethe phase lock logic
circuit will

the dot remains constant .
p ermit the sweep control and sweep
generator to start
another sweep . Sweep lockout, by
the d
ot
frequency and
phase lock loop circuits, is
ignored w hen the F requency

Α simplified block diagram of the F requency R eference
Span/Div is ZERO .
circuitry is shown i n Fig . 2-1 . The frequency to b e
measured (fm), is fed to the 1st mixer in t he p lug-in
module, where it is mixed with t he output from the 1st
L
O .
The sweep rate is controlled by
the ΤΙΜΕ /DIV selector

T he output IF of 10 .700 MHz is fed to the
2nd mixer where
unless

AUTO

p osition

is

selected .

When

AUTO

is

it is mixed with 10 .45
MHz from the 2nd L O and converted
selected,
sweep rate is controlled by α R OM w hich looks at

d own
to
α 250 kHz IF . The 2nd LO frequency is r eferenced
the FREQUENCY SPAN/DIV a nd RESOLUTION
selec-

to 500 kHz, α submultiple of α10 MHz M aster Oscillator
.
tions to determine the swee p rate
. The RESOLUTION and
FREQUENCY
SPAN/DIV selectors are b oth printed circuit
switches that feed
their output into R OMs . The R OMs then

F requency Control Circuits
control the
frequencyspan a nd resolution bandwidth of
As previously described,
instrument
and provide readout d ata to the circuit .
The

, two divide by " Ν " ( Νι and
Ν z)
control loops, with t heir oscillators, d etermine
the fre-
RESOLUTION selector h as α
COUPLED p osition where α

q
uency of the 1st
L
O .
Α 11 .1 MHzto 16 MHz, " Α " oscillator
R OM determines the optimum
resolution for the selected

mixes with t
he
frequency of the 1st L O (10 .7 to 15 .7 MHz) .
FREQUENCY SPAN/DIV . In
the manual positions of the

The
difference is compared with t he 40th s ub-harmonic of
RESOLUTION and
ΤΙΜΕ /DIV selectors, the uncal com-

α
12 to 16 MHz " Β " oscillator in α Δ f/ Δφ d etector . Any
p arator
monitors the sweep rate versus r esolution

difference produces an error
voltage that is fed back
bandwidth
a nd F requency Span/Div setting . It lights an

though α
summing amplifier to pull the 1st L O into α
UNCAL i ndicator when t he display is n ot
calibrated . At the

locked mode
with both Α a nd Β oscillators .
same time α > symbol
p recedes the R eference L evel
readout to indicate
that the readout is not calibrated .
The frequency of both secondary ( Α and Β ) oscillators
F requency R eference

is controlled by =Ν loops . The value Ν is d etermined by
the DOT
frequency control . This control tunes the Α
T he center
frequency of the span is p rogrammed into

oscillator in 100 kHz increments and the Β
oscillator
in
= Ν counters which are p art of α frequency and p hase lock

10 kHz steps . (100 kHz and 10 kHz increments originate
synthesizer
loop
. Two of these = Ν control loops set and

from the 10 MHz master oscillator .) The frequency of the Β
lock t he frequency of two secondary ( Α &Β )
oscillators

oscillator is divided down by 40 so the frequency into the
which are p art of α t hird loop that
controls the 1st L O

comparator steps in 250 Hz increments . If the DOT
frequency . The 1st L O center
frequency, therefore, is

frequency is0 H z,thefrequenciesoftheAandBoscillator
d ependenton the p
rogrammed data in t he = Ν counters .

are 11 .1 MHz
and 16 .0
MHz . The input
to the phase lock
T he frequency span
of the 1st L O depends on the ram p comparator ( Δ f/ Δφ detector) from the =40 source is
amplitude out of the sweep attenuator circuits .
During

400kHz (16 MHz
-
40) . The difference frequencyout of
retrace time, the secondary oscillators are locked
to the

the Α oscillator and the 1st L O mixermustalso b e400 kHz
center frequency . During lock t he
sweep reduces to α

for the system to lock
.
Since the
Α
and
Β
oscillators are

Cir cuit Descri p tio n - 7L5
Service
refe r ence d to t h e same
refere nce (10 MH z master
os-

voltages of t he compa r ators are ap
plie d t hr o ugh logic
cillator)
t he 1st L O is loc k e d
to 10 .7 MH z (11 .1 MHz-

circuitry
to memory capacitors i n eac h oscillato r
loop . The
400 kHz) . F
re q uency ch anges to eit h
er Α or Β oscillato r s

logic circ u itry
gates t he com p arato r refer ence
voltage to
require α c h an
ge in t h e val u e of " Ν " t h
at is loaded i n to

t h is memory circuit
duri n g retrace o r t heL ock p ortio n
of
up/down cou n ters for
t he respective co n trol
loo ps .

t he sweep cycle . This ch arge
or
r
efere n ce voltage on t h e
memory ca p acitor is su mme d wit h t he
swee p ramp from
T
he DOT FRE Q UEN CY will tune eit her
t h eΒ oscillator

t he
fre q ue n cy s pa n (Swee p Co n trol) circuit . T h
e
r
es u lta n t
in
10 kH z steps or t h e Α oscillator in
100
kH
z ste ps . T he

voltage
is a pp lie d t h ro ugh amplifiers to t h eΑ
or Β
frequen cy of t he 1st L O (and t he d ot)
can
t h
erefore be

oscillator to
co
n trol
t h eir frequen cies .
t u ned i n 250 H z
or 100 kH z ste ps depe nd i n g on w h
ic
h
latc h is en able d .
Α more d etaile d bloc k diagra m
of t he F re qu ency
R efere nce circ u it is provided by t he Swee p Co n t r
ol a nd
F
reque ncy R efe r ence Β loc k Diagram (1 α ) in t h e Diag r ams
sectio n .
T he 10
MHz of t he crystal oscillator or M
aster
Oscillator fre q uency is d ivi
d ed d ow n to 100 kH z and
500 kH z by twocou n ters . 100 kH z
is fed to o n e i np ut of α
ph
ase comparator for t h e Α oscillator
loop . It is also
divi d e d dow n to 10 kH z for a pp licatio
n to o n e in p ut of α
ph
ase comparator for t h eΒ oscillato r
loop . T h e out pu t
( M IX ER
PH AS E L OC K
CO
MP
A R ATO R
LJ
9
FRE Q UEN
CY REFEREN C E BL OC K
F I R ST M IX ER

SE CO ND M IX ER
10 .700 MHz 1 F

250 kH z Ι F
(<~N
1ST L O

3
10 .7
MHz TO

U
15 .69975
MH z

2 ND L O

500 kH z REF
10 .45 MH z
Α OSC

100 kH z REF
11 .1 MHz
To
(

16 .0
MHz
Ν
1
T he Α oscillator
o
u t p
ut is mixe d wit h t he 1st L
O
freq uen cy and t h e difference f
r equ e ncy a pp lie d to o ne
i npu t
of α ph ase com p arator an dloop
filter . T h e ot he r
i npu t, to t he ph
ase com p arato r , is t he 40 su
b-freq ue ncy of
t he Β oscillator .
Any d iffe r en ce b etwee n t h e two fr e q
uen-
cies p ro d uces
an e
r ror
voltage w h ic h is a pp lie d to t h e list
L
O to correct and con trol t he
1st L O fre q uency . T he
oscillator fre quen cies can be expresse
d as :
10 MHz
M
AST ER OSC
F ig . 2-1 . Fr e q ue n
cy
r
efe r e n ce b loc k diag r am .
f ιισιιοι
-
f
ιη - ι
-f(8
αει .
άο
Β OSC
=40 16 ΜΗτΤΟ
12 MHz
Ν
2
r __1111
CA L
(100 kH
z)
10 kH z REF
2184-1
REV . Α ΜΑΥ 1978

O u t p ut f r e qu en cies of t h e Α
oscillator and Β oscillator

Β oscillator fre q ue ncy loop, 5 kH z to 200 kH z a
nd 500 kH z
are fed
bac k to Α- Ν and Β
-Ν
circuits . T he value "
Ν "

o r MAX s p an for
t
h
e
Α
oscillato r loop) . Si nce t he loop
assumes de pe nd
s on t h e setting of t he d ot freque n
cy

sen sitivity of t he two oscillato r loops differ
by α factor of
co n trol ci r cuit . For example,
α freque ncy of 16 MH z outof

100, t he atte n uator setti n gs are use d twice
to cover t he full
t he Α oscillator requi r es
an
" Ν "
facto r of 160 to d ivi d e

r
an ge (50 Hz to 500 kH z) of t h e FRE Q UEN CY SP AN /DI
V .
16
MHz dow
n
to 100 kH z, so t he fre qu e ncy i n
to
t he ph ase

When t h e FRE
Q
UEN
CY SP AN /DI V is not i n t he MAX
com p arator eq
uals t he 100 kH z at t he ot h er inp u t
to t he

span positio n , t h e MAX switc h
closes to allow α dot mar k er
com p arator . As t he
d ot fre q uency is c h anged, t he " Ν "
voltage to be summed i n wit h t he Α oscillator
co n t r ol loop
facto r i n to eit h er t he Α-Ν
o r Β
-Ν
circuit ch an ges to

so t h e dot ca n be p ositio ned alo n g t he left portio n
of
t h
e
increase o rd ecreaset h eAor Β
oscillatorfre quency.Since

5
ΛηΗ
zdisplay .
t he 1st L O is slave d to t h ese oscillators, its
freq uency must
also
c
han
ge .

A turn-on circuit (on t h e left si d e of t h e diagram) fo r ces
T he

F re qu ency

Spa n /Div

circuit

determin es

t h e

α
f r
ee
r
un and no r mal selection of t h e trigge r ci r cuits, αdot
amou n t t h e Α or Β oscillator freq uency
is swept
.
T h e

f r e qu en cy
of 000, refe r en ce level of+17 dB m, an d Dis p lay
swee p h
orizontal voltage is a p plie d t h ro u g h an atte nuato r

Α ,
Disp lay Β sto r e mo des w h e n p
ower is a pp lied .
a nd bi nary switch
to αsu mmi ng poi n t, eit he r i n t he Α

R
eadout
m emory or Βmemory r
efere n ce voltage line . T he FRE-

Α block diagram
of
t he R
ead out circ u its is sh ow n in F ig .
Q UEN CY SPA N /DI V selector
sets t
he
amo un t of swee p
2-2
. Along t h e left si dea r e t he fro n t p an el selecto r
s .
T h
e
atte nu atio na
nd t hus t h e fre q uency span . T h e output of

DOT FRE Q UEN CY cont r ol drives α TEKTRONIX ICw h ic h
t he SP A N /DI V selector
is also fe d to α RO Mw h ic h loo ks at

p
r
ovi d es t h e col u m n d ata for t h e to p h o r izo n tal r ead o u t
t
he
selected s pan an dch ooses o ne of t hr
eeswee p ou tp u ts

locatio n
on t
heε
rt . Cu rr en t fo r t he Hz and kH z readout is
f
r om t h e bi n ary co n trolle d switc h . T h ese ram ps a r e u sed
supplie d byα resisto r mat r ix . R
ow d ata also comes from α
for
d iffere n t s p
an / d
iv
f r e qu en cies (50 Hz to 2 kH
z,
for
t h e

fixed resisto r matrix .
DOT

U
830

CO LUMNDATA

Α
37
FRE
Q UEN CY

TOP
I-

i

Α H OR IZO N TA
L
REFEREN
CE
LEVEL
RE SO LU TIO N
ΤΙΜΕ /DI V
dB
m/
dBV
O FFSE T
REF
LEVEL
R OM
U 2235
FRE Q UEN CY

R O R OM
FR
O
M F IX
E D
RE SISTO
R
M
AT R IX
FR O M FIXE D
RE SISTO R M
AT R IX
UNCA L
V AR
L I N L ATC H

R O W DATA
SP A N ~~
U 801)

Α
38
BOTTOM
Α H O R IZO N TA L
FR O M
FIXE
D
RE SISTO R M
ATR IX
LOG/ L I N
F ig
.
2-2 . Fun ctio n b loc k of r ea dout ci r c u its .
Cir cuit
Descriptio n -71-5 Service
RO W DATA
CO LUMN DATA
CO LUMN DATA
RO W DATA
CO LUMN
DATA
RE SISTO R
M AT RIX

Ι

RO W DATA
Β37
Α 37
Β37
Β38
TOP
RIG
HT VER TICA L
A38
BOTTOM
R IG H T VER TICA L
Β 38
2184-2

Circuit Descri p tion-71- 5 Service
Th e REFEREN C E LEVEL d rives U 2235 w h ic h p rovi des

Thea ddr ess is d e r ive d from t he h o r izo n tal sweep ram
p .
colum n d ata cu r rent fo r t he to p rig h t vertical rea d out

Th
is is α 10
volt negative-goi n g ra m pcentered a r ound t h e
positio n . T he out pu t of t he U 2235 is influe n ced by t he

Dot fre q ue ncy . The ram p is offset (up to p lus o r mi nus 10
setting of t he d B m/ dBV selector an d t he offset set by t he

volts) as t h ed ot frequency is tu n ed so t he sweep ramp
in p ut impe d ance of t h e pl u g-in mo d ule and t he refere nce

r an ge can run from -10 V to +10 V (-10 V to 0 V at one
level selecte d .
T
he L I N switc
h
latc
h
ch
anges
t
h e row data

e nd and

0 V to +10 V at t he ot h er)
.
T h e sweep is
so t
he r
eadout is
i n n V, μ V, an d m V instead of dB m ord BV .

co n verted, by t h e h orizo n tal Α /D co n verter, to add
r ess
(T h e column data is also c han ge d so t he cor r ect nu mbers

d ata for memory
.
M emory consists of α 4096
(512 χ 8) bit
are read o ut .)

R
A
M
and α
1024 (1024 χ 1) b it overflow oroffset R A M . T he
4096 bit R AM has 512 h orizo n tal access lines . M emory is
divided i n to an Α and Β sectio n wit h 256 lines assigned to
T h e FRE Q UEN CY S P AN /DI V d rives R OM U 800 w h ic h
eac h . Address locations ared etermi ned b y t he L S B (least
provides t he col u m n data fo r t he b ottom Α h o r izontal

sig n ifica n t bit) of t he h orizontal address word . Si nce t
he
p ositio
n .
R ow data is
from
α
fixed r
esisto
r mat r ix . If zero

L SB of t h is wor d alter n ates
wit h
anycou
n t, t h
e
Α an dΒ
span is selected, it r eads i n time/ d ivisio n .

locatio ns i n memory are a dj ace n t wit h t he odd bit
assig n ed to Α memory and t he eve n bit to Β memory
sections .
T he RE SO LU TIO N selector dr ives α resistor matrix t h at
p rovides b ot h colum n an d row d ata to t he bottom rig
h t
vertical p art of t he d is p lay . T h e colum n data also gets t
h
e
10 dB, 2 d B, or ; if L I N mo de is selecte d , t h at p ortio n of
t he

T he h orizo n tal address is α10 bit word . T h e first 9 bits
d is p lay is α sp ace .

(2
9 )
are derive d from t h e swee p ram p and store d in t he fi r st
RA M . T h e
te
n
t h bit (M S B) is store d in t he overflow or offset
R A M . T h is te n t h bit sig n ifies t he offset (to t he rig h t
or
left
Dis
p lay
P rocessing

B loc k Diag r am

c

of cen ter screen ) of α given address a nd si nce t he offset
can b e up to ±10 V, α20 volt ram p ca p ability is p rovi d ed .
T
he video
sig n
al
from t he I F processi ng c h ain is fe d
t hrough switc h U 735 B to an Α /D co n verte r . T h e d igital
d ata from t h e co n verter is t h en placed i n memory . It is read
from memory and d isplayed at t h e comma
n
d of
Display Α

At t h e slower swee p speed s, t here are numerous wor ds
an
d Display
Β
selectors .
B efore t he vertical d ata is placed

of vertical data for eac h h orizo n tal address location . T
h
ese
in memory, it may be eit her average d or pea k detecte d .

n ume r ous words of vertical data are
average
d ,
by t he
V ertical data is placed at an ad dress i n memory derive d average
calculator, so wit hα 10 seco n d swee p rate, up to
from t h e sweep h o r izontal waveform . How t he a dd ress is

20,000 wor dsare averaged at αh orizontal address . At t he
d erived will be descri bed later .

2 ms swee p rate, only fo u r wor ds would be average d .
R eferri ng to t he lowe r left side of t he d iagram, t he 1st
L O tune voltage ram p is fed to an absolute val ue circuit,

At t he end of an 8 bit vertical word α sync pulse is sent
w h ic h loo k s at t h e ramp excursion
. If t h
e
ramp excee ds

out
on
t h e E OC (e nd of co n version) line to t he d is p lay
certai n limits, t
heout p ut from t he comparator is an

co n trol timi n g bloc k and t h roug h t he syn c h ro n izer to t he
overspan
sig n al w h ic h ope ns t he video pat h t hroug h ave r age calculator . Wh en t he sweep h o r izo n tal sig n al h as
switc h U 735 B . Α d o level is placed on t he li ne to p rovide α

traverse d far en oug h to generate α new h orizo n tal a d-
baseline for t h e d is p lay . U nless overspan is detecte d , t
he

d ress, t heE OC starts α t h ree cycle seq ue nce t h at w r ites α
video sig n al is fe d to display switc h U 735C and t he vertical

vertical word in memory at t h at ad d ress . T h is process
an alog-to-digital ( Α /D) converter .
T h
e
video i nformation

re q uires 27 μ s (3
χ9
μ s) .
T h
e rest of t h e time is
utilized in
is co n verted to an 8
b it d ata wor d t h at appears in serial

t he d isplay mode
to
rea d from memory . At t he begi nn i n g
form
on
t he Data Out line . T h e cloc k fo r t h is converter is

of t h e t h ree cycle process t he first cycle generates Start
1 MH z, derive d from t he 10 MH z master oscillator, so t h e

Divi d e to t he average calculator . T he average circuit
vertical data b its are 1 μ s ap art . Since t here are 8 bits p er

divi d es t he accumulate d vertical d ata by t he n umber of
wo rd p lus α sy n c p ulse, eac
h
word ta
k
es 9 μ s or
t he wor d
words during
t h
at period,
an d t he res u lta n t o r qu otient is
rate is
111 kH z . T h e vertical data out, in serial form, t hen

gated i n to memory on t h e M at h li n e, w h e n t he seco nd
goes to an average calculato r wh ere it is eit h er average d or

cycle

or

W rite Cycle arrives .

W rite Cycle sig n al

is
pea k detected . T he output (on t he M at h line) is t hen stored

ge n erated only w hen V alid is p rese n t . V ali d is n ot present
at some address in memory .

d uri ng retrace or w h e n t he d ot fre q uency is ch angi ng .
2-6
REV . Α ΜΑΥ 1978

The o u t p ut of t he h orizontal d isplay generator con sists
of readout addresses to
memory and α syn t h esized
h orizontal sweep ram p for t h e Store h orizo n tal li ne .
T h erefo r e, as t he vertical d ata is rea d from memory, α
correspo nd i ng c h ange occurs i n t he h orizo n tal sweep
voltage so t h e vertical data written in memory is d u p licate d
an d d isplayed ap p ro p riately
w h
en it is read out
. Data
is
stored i n memory at t
he
rate set by
t he Time/Div selector ;
h
owever,
it is rea d from memory at α consta n t rate .
If Display Α is selecte d , t h e L S B for t he ad dress out of
t he h orizontal d is p lay ge n erator remains α 1 . T h e cou n ter
cou n ts in odd numbe r se quen ce so only data
in Α
sectio
n
of memory is read .
If
Display
Β
is
selecte d , t hen t he
counter cou n ts in even number seque nce and data i n Β
memory, is rea d out . If Dis p lay Α and Display Β are
selecte d t hen t h e
L
SB for t
he
address
alter n ates an d data
is read
first from Α t hen from Β memory . If Save Α is
selected, Α memory is n ot upd ate d during W rite Cycle . If
Display Α is selected along wit h Save Α , t h e n t h e data
stored i n Α , w he n Save Α was pus h ed, is read out .
Ci r cuit Descri p tio n -71-5 Service
logic also p rovi des blan
k
i n g and un bla
nk ing
to
t he Ζ axis
by bla nk i ng j ust before t he dot transitio n an d un bla nk i ng
duri ng d ot p rese n tatio n . It also b la nk s d uri ng t he tra n si-
tio n bac k to normal vertical a nd h orizo n t al p ositioning
.
Data into Ζ axis a nd d ot logic are Ze
r
o Spa
n , Display V ali d ,
and
t h
e mai n frame
d ata suc h
as
C h a nn el a nd M ode
informatio n .
P eak /Average refere nce level originates wit h t he
PEAK/AVERAGE front panel co n trol
. T h
is
r
eference is
com pared
wit han analog sig n al out of t he vertical analog-
to-digital co n verter . If t he vertical signal excee ds t he
refere n ce level set by t he co n trol, t h e average calculator
selects pea k value . Sign als below t h is refere nce are
averaged . T he co n trol fu n ctio n s as α P eak /Average selec-
tor only i
n
t he Store mo d e
.
Division
between average and
p eak d is p lay is
i n
dicated
by α
cursor
οη screen . In t h e non-
store mode
t he co n trol o p erates as α b aseli ne clipper .
V ertical i n formatio n below t h e level set by t he control is
bla nked .
T h is completes t he bloc k
diagram d escri p tio n for t h e
V ertical d ata out of memory goes to t he vertical dis p lay

71-5
circuitry .
gen erator on t h e M emory Data li ne . It is converte d to
analog d ata t hen processe d to
t h
e
display circuits . Α
timing sig n al,
from
t he
vertical an alog to digital co nve r ter

D E TAI LE D CI
R
CU
IT D E SC R I P TIO N
bloc k , co n trols
w h
en
d ata is rea d from memory . Data can
only be read during
t he R ead Cycle . Wh en eit h er Disp lay Α

Swee p Co n trol

3 ΟΟ
or Di
sp lay Β is selecte d , t he d is p lay control b loc k se nd sα

<~
Store signal to b ot h t he vertical a nd h orizontal display

T h is p ortio n of t he circuit d escri
p tio n covers t he A u to
switc hes ( U 735A, U 375C) . B ot h switc hes t hen select only

Sweep, F re q uency Sp a n and
its R ea d out, an d Trigger
d ata from t he ve r tical d is p lay generator a
nd t he synt h esiz-

circuits . Diagrams 3 t
hr
o
u g h6 cover t h ese circuits .
ed swee p ,
from t he h orizo n tal display generator for t he
vertical and h orizontal outp ut stages .
T h e Auto Swee p circuit sets t h e swee p rate accor d
i
ng
to t he ΤΙΜΕ /DI V selections ; or, if t he
ΤΙΜΕ /DI V selector is
T he i n verted
sweep co n tai n i ng dot mar k er p ositio n is

set to t h eA U TO positio n , t
he circuit automatically ad ju sts
summed
wit h t h e " d ot position" w hen Q735 is on, at t he

t he swee p

r ate as α
functio n of t h e FRE Q UEN CY
i np ut to t h eh orizo n tal outp u t stage . T he summatio n of

SP
AN /DI V and RE SO LU TIO N selector setti n gs . If t h e
mi nus sweep wit h dotp osition plus " d ot p osition" is
minus

RE
SO LU
TIO N is at t he CO UPLE D positio n , wit h t he
sweep . T h is is am p lified by
t he outp ut amplifier and

ΤΙΜΕ /DI V at AU TO, t he sweep rate and r esolutio n are
ap p lied to
t h
e
crt d eflection plates . Wh en Q735 is off, only

automatically com p uted as α fu n ctio n of t
he selecte d
t h e " d ot p
osition" is a p plied to t he outp ut amplifierand t he

freque n cy s p an to k eep t he d is p lay calib
r ate d . Wh en t he
crt deflection
plates . T he dot is t h erefore displaye d sweep rate is
n
ot
compati b le to t he resolutio n and
i n
depend
ent of swee p . Sweep h orizontal is also app lie d
frequency s p a n, t he circuit activates α fro n t p an el UN CA L
t hroug h αsep arate amplifier to t he f r o n t panel H O
R IZ

i n dicator .
OU T j ac k an d pi n Α 3 of t he mainframe
i
n terface
.
The ΤΙΜΕ /DI
V
selector
assembly ou t pu ts α5 bit
T he Ζ axis an d d ot logic bloc k determine w h e
n
t he dot

ad dress, as sh
own i n t h e trut h table . F our b its of t h is
is to b e displaye d . An outp u t called Dot is fe d to

ad dress are fe d to one side of four section multiplexer
m ultiplexer switc hes in t he vertical and h orizo n tal
lines
.

U 525 . T he Β inputs to t he m u ltiplexer are selected
w hen
T h is low discon n ects t he vertical a nd
h orizo n tal d rive to

t he Select ( p i n 1) line is h ig h , so
t h
e
ΤΙΜΕ /DI V assem b ly
t he mai
n
frame and p ositio ns
t h
e
d
ot
a pp ro p riately . T h e

output is switc hed t
h
ro ugh to
t h e swee p generator circuit

Circuit Description-71-5 Service
(Diagram 6) . If t h e A U TO p ositio n is selecte d , U 530D is

timing resistors as i nd icated by t he ad dress ta b le wit
h i n
enabled . T h is p ulls pin 1 of U 525 low a nd switches t he

t he symbol for U 695 . V oltage refere
nce fo r t he selecte d
m u lti p lexer to its Α inputs . T h e swee p rate is now α

timi ng r esistor is t h e out
pu t of o p eratio n al am p lifie r
fu n ctio n of t he add r ess out of R O M U 515 .

U 690A . Wh e n Q680
is turned on, timi n g voltage is
increase d by α
factor of two w h ic h i ncreases t he sweep
s p ee d pr o p
ortionately . Ta b le 2-1 lists t h e Time/Div selec-
T h e outpu t ad dress of R OM U 515 is α function of t h e

tio ns with t he o u t p ut add r esses an d t he co r respo
nd ing
FRE Q UEN CY SP A N /DI V an d RE SO LU TIO N cont r ol set-

a dd resses for U 695, Q680 gate, an d pi n9 of U
680C . F or
tings . T h is ad d ress is also fe d to t h eΒ i np uts of com-

exam p le ; 50 ms connects timi
n g resistor R 694, conn ects
pa r ato r U 540 w he r e it is compare d wit h t h e ΤΙΜΕ /DI V
timi n g capacitor C71213, a
nd t u r ns off Q680 to add R 686 as
setti n g . If t h eco de from t h e ΤΙΜΕ /DI V
selector
is less t han
part of R ; (i nput resistor)
for operational am p lifier U 680A .
t h e co d e out of ROM U 515, t he ou t pu t of com p a r ator U 540
goes h ig h an d , w h en inverte d by U 520 E , p ulls t he Un cal
li n e low to activate t he UNCA L lig h t an d ge n erate α (>)

The M ille r i n tegrator is gate d on
b y t he +Gate sig n al
symbol as α p refex to
t he refe r ence level rea d o u t .
into t
he
base of
Q705 . T h is gate switc hes Q700 off and
allows t he M iller integrator outp ut to r amp up .
T he outp u t
Wh en t h e RE SO LU TIO N selector is i n t he CO UPLE D

of t he swee p generato r is fed to on e
i
np ut of co
m parato r
positio n , R OMU 515 selects resolution t h at is compatible

U 575A w h ose outp ut switc h es
h ig h w h en t he i n pu t ram p
for t he f r e qu ency span selecte d . T h e CM OS outputs for

r eac hes t h e r eference
level, set b y t h e divider n etwo rk on
t he FRE Q UEN
CY SPA
N /DI V
assembly are co
n
verted to

t h e ot h e r input of t
he
co
m paratoror a b out 8 .9 volts . T h is
TT L by t h e buffe r s ( U 510A, Β , D, Ε , a nd F) to accom-

Swee p
I nh ibit sig n al is fe d back to t he sweep co n trol ICto
modate RO M (0650) i n t he F re quen cy Sp an circ u it .

termi n ate t he sweep gate . Un less Manual swee p
h
as been
selecte d , t h e swee p r a m p is also fe d t hroug h
m u lti p lexe r
U 680 B to operatio n al amplifier U 685A
. Gain of U 685A is
T h e outp uts of t h e ΤΙΜΕ /DI V an d

FRE Q UEN CY

abo u t 1 .2 p roduci n g an out
p
ut
ramp
of
a pp roximately 10 .4
S P AN /DI V selectors, are Da r li ngton p ai r s w h ic h pull d own

volt . T h is r amp is
fed
to
t he fre qu en cy spa n atte nuator
to about 1 .0 volt . T h e low state is offset two j un ctio ns

ci
r cuit, contai n i n gR 660- U 665, an d to t he h o r izo n tal
b elow g r ou nd , by C R 64 an d CR 66 t hr oug h R 512, to-15 V ;

swee p p r ocessi ng ci r cuit .
so α logic low at t h eo u tput is a b out gro un dp otential
.
L
ogic
h ig h
is pu
lle d
up
t hr
o
u g h r esistors in resistor p ack

TA BLE 2-1
R 60 .

Trut h Ta b le for
ΤΙΜΕ /DI V
Selectio
ns
T he arm
of
t he RE
SO LU
TIO N
switc
h
is co
nn
ected to
t he collector
of
Q70 . W it h r esistor pack R 60A in t h e circuit,
t he tra n sistor is satu r ate d a nd g r ou n d retu rn is fur n is h ed
to t he switc h . W it h t he r esisto r pack r emoved t he base of
t he t r a n sistor is conn ected to t he remote p rogram li ne a nd
t he ou tput is d epen d en t on t he exter
n
al
p r
og r am
.
Diodes
C R 74 t h roug h C R 76 p rovi de isolatio n .
T here are five li n es t h at determi ne t he sweep s p eed ;
fou r from multi p lexer U 525 an d t he fift h from t he outpu t of
N A ND gate U 535C . T he swee p gen erator (Diagram 6)
co n sists of M iller i n tegrator U 700 wit h timing capacitors
C712A
a
nd C712 B .
Ca
p
acitor
C712 B
is
switc h
ed
i n
to
t h e
timi n g circ u it w he n t he i np ut li ne to p i n 9 of multi p lexer,
( U 80C) is low . C712 is i n t h e ci r cu it for swee p rates of
10 ms or slower . Wh en t h e level at p i n 9 is h ig h , t he switc h
open s,
a nd C712 B
is
out of t he timing circuit .
Timi ng r esisto r s are selected by
multi p
lexer U 695 .
Co
n trol li nes Α , Β , and C ( p ins 11, 10, and 9) select t he
ms
.1
.2
.5
1
2
5
10
20
50
sec
.1
.2
.5
1
2
3
10
AU TO
ΤΙΜΕ /DI V
ST ST ST ST ST
5 4 3 2 1
000 0 0
000 0
1
000 1 1
0 0 1 0 0
0 0 1 0 1
0 0 111
0 1 000
0
1
0 0
1
0 1 0 1 1
0
1 1
0 0
0 1 1 0 1
0 1 1 1 1
1 0 0 0 0
1 0 0 0 1
1
0 0
1
1
1 0 1 0 0
1 111 0
S WEEP CO NT R O L
U 695
Α Β C
0 0 1
0 0 1
000
0 1 1
0 1 1
0 1 0
0 0 1
0 0
1
0 0 0
0
11
0 1 1
0 1 0
1 0 1
1 0 1
1 0 0
111
1 1 0
Q680 Ι
GAT E U 680C-9
1
0
0
1
0
0
1
0
0
1
0
0
1
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0

H oldoff timing capacitors, for the sweep control IC

output line . F
or
example ; with α FREQUENCY SPAN/DIV
(U580 on
Diagram
5),
are
C728 and C726 .
When t he logic

of 50 kHz, input lines Α a nd Β to U 670 are low . Address 00
input (pin 11) to multiplexer U 680A is low, C726 p arallels

(into U670) switches the sweep output of U 665to pin 12 of
C728 to increase the time constant . The other output of

U 670 to d rive the Β oscillator . Table 2-4 lists the sweep for
U 680A ( p in 13) drives the b ase of the transistor i n U585C

each S PAN/DIV setting . The table bypasses R OMs U 510
to provide intensity limiting to the mainframeattheslower

and U 650 .
sweep s p eeds (below 10 ms/div)
. At
faster
speeds, the
input line is h igh and p in 13 is grounded, so U 585C is

The Max Span Dot P osition a djustment (R655) offsets
biased off to remove intensity limiting . In manual modeor,

the d o level of the memory
voltage
so
αvoltage of 0
when op erating with s pans other than 0 H z, the low state

corresponds to
center screen (2 .5 MHz) . It also offsets the
into U 595D turns U 585C on to p rovide intensity limiting .

d o level of the 1st L O tune voltage so acenter f requency of
Intensity limiting is therefore provided
for
manual sweep

2 .5 MHz corresponds to 0 V at the output (pin 3) of U 675B
operation, sweep rates b elow 10 ms/div, an d 0 Hz span

for centering the overspan clipping .
o p eration .
The 1st L O tune voltage is α positive-going ramp,
Multiplexer U 665 selects the attenuation ratio for the

centered a round some do
level set
by the
DOT FRE-
10 .4 volt sweep ramp t hrough resistor pack R660 . The

QUENCY control . The amplitude of this sweep voltage
attenuation a ddress (in at A, Β , a nd C of U665) determines

d
epends on
the setting of the FREQUENCY SPAN/DIV
t he attenuation . The sweep out of U 665 is then fed t hrough

selector . U 675A, U 575C, and U575A limit the excursion of
multiplexer U 670 to one of four output lines . Three of

thewaveform .U675B,anon-inverting amplifier, d rivesthe
these (1 Α , 1 Β , a nd #2) drive
the Α
a nd
Β
oscillators
which

negative input of operational amplifier U 675A . As the
establish
t
he
frequency span . The fourth line is for

sweep ramp crosses its center p oint, d iode CR660 d is-
optional use if desired . the address within t he IC symbols

connects and
the
p
olarity of the input signal to the
indicate the sweep ramp path t hroughR660 and U670 . F or

comparator U 575C reverses . The input waveform to pin 7
example ; when t he input address to U 665 is 110, pin 2 of

of U 575C is therefore V s haped . This input is referenced
U665 is connected to the output . The sweep is attenuated

(by α voltage divider) to about 4 .5 volts . If eitherexcursion
t hrough R660by the combination of
the 4 .00 k a nd 1 .33 k

of the V s haped waveform
exceeds this reference, α
resistors .
Table 2-2 and 2-3 show the input and output d ata

positive output signal is p roduced w hich represents an
for ROM U650 and multiplexers U 665 and U670 . Table2-2

overspan . This overspan voltage is fed to α multiplexer
shows the Data Out of U 650 with t he corresponding sweep

(U735B), in the video processing chain, and the output of
TABLE 2-2
Input and Output Data
for
U 650 (8223
R
OM)
FRED

INPUT

OCTAL DATA

OCTAL ~
SPAN/DIV ADDRESS(BINARY)

~
E OUIV O UTPUT(BINARY)

~
E OUIV

S WP
Α °

Α 3

Α
2

Αι
. Α ο

1 : 1 -
B
t Β 6 B s Βα Βι Bz Βι
B o
Circuit Description-71- 5 Service
MAX SPAN

1

1

0

1

1

33

1

1

0

1

0

1

0

1

325
200 kHz

1

1

1

1

1

37

0

0

1

1

0

1

0

1

065
100 kHz

1

1

1

1

0

36

1

0

0

1

0

1

0

1

225
50 kHz

1

1

0

0

1

31

1

0

1

1

0

1

0

1

265
20 kHz

1

1

1

0

1

35

0

0

1

1

0

1

0

1

065
10 kHz

1

1

1

0

0

34

1

0

0

1

0

1

0

1

225
5kHz

1

0

0

1

1

23

1

0

1

1

0

1

0

1

265
2kHz

1

0

1

1

1

27

0

1

1

1

0

1

1

0

166
1 kHz

1

0

1

1

0

26

1

1

0

1

0

1

1

0

326
.5 kHz

1

0

0

0

1

21

1

1

1

1

0

1

1

0

366
.2 kHz

1

0

1

0

1

25

0

1

1

1

0

1

1

0

166
.1 kHz

1

0

1

0

0

24

1

1

0

1

0

1

1

0

326
50 Η z

0

1

0

1

1

13

1

1

1

1

0

1

1

0

366
0 Hz

0

0

1

0

0

04

1

0

1

0

1

1

1

1

257
Β

Α
Control

Control
L ine U 670

L ine
U 670
1 Α
113
113
113
113
1 Β
1 Β
#2
#2
#2
#2
#2
#2
0

Circuit Description-71-5 Service
t he detector is d isco nnected from
t he vertical output

con
trol . T h e d ot always r e presents rea dout f r eq uen cy .
am p lifier .
T h
e ve
r tical d isplay
now
b ecomes α d o voltage

T h e do level, set by t he DOT MKR co n trol ( R 50) feeds
w h ic hp r oduces α trace at t h e b ottom of t he sc r een . 1 η non-

t h ree of t h e inpu ts for t h e bottom h alf of U 670 . If t he
store mo d e t h e overspa n po r tio n is blan k ed .

co n trol a dd ress to U 670 (f
r
om
R
OMU
650) is anyt h i n g
exce p
t 10, t h e do level of t he DOTMKR cont r ol is switc hed
t hr oug h U 670 to t he i nput of ope r atio n al am p lifie r U 685 B .
Ad d ress code 10 occurs only
w
hen t h e FRE Q UEN CY
T he lower h alf of m u lti p lexer U 670 p rovides α do offset

SP A N /DI V selector is in MAX sp a
n p osition . T he offset
to t he swee p ram p . In t h e MAX s p an p ositio n
,
t he DOT

voltage now comes
f r
om
t h e syn t h esize r memory circuits .
FRE Q UEN CY cont r ol moves
t h
e dot (rea d out) frequency

The
d ooutp
ut of
U
685 B sets t h e i npu t do level of t he swee p
across
t he screen .
In ot
h e r SP A N /DI V p ositio n s, t h e d ot is

am p lifier U 685A to p rovi d e offset to t he Swee p H orizo n tal
at ce n te r sc r een un less it is move d by t he DOT MKR

ramp .
FRE D
SP A N /DI V
MAX
.2 MHz
.1 MHz
50 kH z
20
kH
z
10 kH z
5 kH z
2 kH z
1 kH z
.5 kH z
.2 kH z
.1 kH z
50 Hz
0 Hz
TA BLE 2-3
I n p u t Data to t h e Fr e qu e ncy Sp a n " RO M S"
U 515
FRE
D SP
A
N /DI V
~

FRE D SP AN /DI V
S W ITC H

Ι

INPU TS
TC T J TB ΤΚ TD
Ι
Α 8 Α 7 Α 6 Α 5 Α 4
MAX

0 0 000 111 1 0
.2 MH z

0

0

0

1

0

1

1

1

1

1
.1 MHz

0

0

0

1

1

1

1

1

0

1
50
kH
z

0

0

1

0

0

0

1

1

1

0
20 kH z

0

0

1

1

0

0

1

1

1

1
10 kH z

0

0

1

1

1

0

1

1

0

1
5 kH z

0

1

0

0

0

1

0

1

1

0
2
kH
z

0

1

0

1

0

1

0

1

1

1
1 kH z

0

1

0

1

1

1

0

1

0

1
.5 kH z

0

1

1

0

0

0

0

1

1

0
.2 kH z

0

1

1

1

0

0

0

1

1

1
.1 kH
z

0

1

1

1

1

0

0

1

0

1
50 Hz

1

0

0

0

0

1

1

0

1

0
0 Ητ

1

1

1

1

1

0

0

0

0

1
TA BLE 2-4
I np ut an d Output Data for
FRE
D
SP AN Mu lti p lexers, B ypassing U 510 a nd U 650
FRE D SP
A N /DI VS W
ITC H

Ι

U 670
TC T J TB ΤΚ TD
( F S5) ( FS4) ( FS3) ( FS2) ( F S1) Ι Β Α

S WP
0 000 0

1 0

1 Α
0 0 0 1 0

0 0

1 Β
0 0 0 1 1

0 0

1 Β
0 0 1 0 0

0 0

1
Β
0 0 1 1 0

0 0

1 Β
0 0 1 1 1

0 0

1 Β
0 1 0 0 0

0 0

1 Β
0 1 0 1 0

1 1

#2
0 1 0 1 1

1 1

#2
0
1 1 0
0

1 1

#2
0 1 1 1 0

1 1

#2
0 1

1

1

1

1 1

#2
1 0 0 0 0

1 1

#2
1

1

1

1

1

0 1

0
U 650
I NPU TS
Α 4 Α 3 Α 2 Α 1 AO
1 1 0 1 1
11111
1111 0
1 1 0 0 1
111 0 1
111 0 0
1 0 0 1 1
1 0 111
1 0 1 1 0
1 000 1
1 0 1 0 1
1 0 1 0 0
0 1 0 1 1
0 0 1 0 0
U 665
C Β Α
0 1 1
000
0 0 1
11
0
1 0 0
1 0 1
0 1 0
000
0 0
1
1 1 0
1 0 0
1 0 1
0 1 0
1 0 0