Tektronix FG 502 User manual

Te k tronix, Inc .
Ρ . Ο . Box 500
B eaverto n , Orego n 97077

Serial Number
070-1706-01
7 tIctro nb c
CO MM ITTE D TO E XC ELLEN C E
PLE AS E
CHE CK F O R CH AN G
E INF O RM ATIO N
AT THE
RE A R OF T H IS M A NU A L
F
G
502
FUNCTION
G
ENER ATO R
I N ST RU
CTIO N M A NU A L
F i r st P rinting OCT
1973
R evised
ΜΑΥ 1981

TABLE OF CONTENTS
Page
LIST OF ILLUSTRATIONS

...... ... .........................
..
. . .... . ...... .ii
Section
1 Specification ... . . ..................... ................. . 1-1
Section 2 Operating Instructions ................... . . . .... ..
........ . 2-1
WARNING
THE FOLLOWING SERVICE INSTRUCTIONS AREFOR USE
BYQUALIFIED
PERSONNEL ONLY . T O AVOID PERSONAL
INJURY,
DO
NOT PERFORM
ANY SERVICING OTHER THANTHAT CONTAINED
IN OPERATING
INSTRUCTIONSUNLESS YOUARE QUALIFIED TO DO SO .
Section 3 Theory of Operation . . . . . . . ................................
3-1
Section 4 Calibration Procedure . . . .... ............................... 41
Performance Check . . .... ............................... 41
Adjustment Procedure ... ................................ 45
Section s
Maintenance
............. . . . ............................
5-1
Section 6 Options . ................. . . ............................ 6-1
Section 7 Replaceable Electrical Parts ...... ...........................
7-1
Section
8 Diagrams and Illustrations ..... . . . ........................... 8-1
Section 9 Replaceable Mechanical Parts . . . . ............................
9-1

L IST
O F
ILLUSTRATIONS
Fig
.
No .
P age
F G502 FUNCTION
GENERATOR
.... . . . . . . ......... .........
.."..... .
vi
2-1 F G
502 I n stallatio
n an d removal .
. ............ ....... ..................
2-1
2-2
Controls a nd Con
n ecto r s ........ ...........
.
... ... .................
2-2
2-3 Imped an ce
matc h ing n etwor k t
h at p rovi d es minimum
atte nu atio n ............... 2-4
2-4 O utp u
t waveforms availa
b le from t h e F G 502
.... ...... .... . . .............
2-5
2-5 G
r ap h s h owi n g r a n ge
of V C F fre que n cies .......
. . . .... .......
. . . . . . . ....
2-5
2-6
Swept fre q ue n cy
ra n ge wit h 10 V
sig n als app lie d to V C
F 1 Νco nn ecto r ...........
2-6
2-7 Ph ase
relatio n s h ips b etwee
n OU T PU T waveforms an
d TR IG O UT
waveform ....... 2-7
2-8 Analyzi
ng circuit o r system
res po n se ...........
. . . .... .......
. . ....... .
2-7
2-9 To
n e bu rst gen eratio n
o r ste pped f r e quency
m u ltiplicatio n ...
................
2 - 8
5-1
Semico ndu
cto r d evice lea d co n
figuratio n fo u n d in t h e TM
500 family ............
5-5

Terms In T
h
is Manual
CA U TIO N stateme n ts iden
tify cond itio n sor practices t h at
co
u l d res u lt i n da m age to t h e e q ui p me n t or ot h er pr op erty .
W A RN I N G stateme n ts i den tify con d itio ns o r pr actices
t h at co u l d r esult in pe r so n al i njur y or loss of life .
Te
r ms As M ark ed on E q u ipme n t
CA U TIO N i nd icates α pe r so n al i nju ry hazard n ot im-
me d iately accessible as o ne rea d s t he mar k i n g, o r α
h azar d to p rop erty i n cl ud i ng t h e eq ui
p
me
n t itself .
DA N
G
ER i nd icates α perso n al i nj ury h aza r d imme d iately
accessi b le as one rea d s t he ma rk i ng .
Sym b ols AsM ar k edon E qu ipment
P
ower
Source
O PER
ATO R S SA FE TY S UMM A R Y
DA N G ER - H ig h voltage .
Pr otective g r o und (eart h ) termi
n
al
.
ATTENTION
- r efer to m anu al .
T h is p ro d uct is i
n
te n ded to
operate f r om α p owe r so urce
t
h at will n ot
apply
mo r e t h a n 250 volts r ms betwee nth e
sup p ly co ndu ctors or b etween eit h er su pp ly co ndu ctor
a nd grou nd . Α pr otective gro und conn ectio
n
byway
of t he
gro u n d i n g co ndu cto r i nth e power co
rd is essen tial for
safe operatio
n .
Grounding t he P ro d uct
T h is p ro duct is gro und e d t h roug h t he gro und i ng cond uc-
tor of t he p ower cor d . To avoi d electrical sh oc k , plug t h e
p ower cord i n to αp roperly wi r ed r eceptacle before
co nn ecti n g to t he p ro d uct i np ut or o u t p ut
termi n als . Α
F
G
502
pr otective groundconn ection by way
of t he gro und i n g
co nductor i n t he p ower cor
d is esse n tial for safe ope r a-
tion .
Da n ger
Arisi ng F rom L oss of Gro u nd
Up o
n loss of t he protective-gro und co nn ectio n , all
accessible
co nd uctive p arts (i n cl u di ng k no b s a nd con-
trols t h at may a pp ear to b e ins u lati n g) can re nd e r an
electric sh oc k .
U se t he P rope r P owe r Cord
U se only the power co r d a n d conn ector s p ecified
for
your
product .
Use only
α power cor d t h at is i n good con d itio n .
U se t he Pr o p er
F use
To avoi d fire
h aza rd , use only t he f use of cor r ect ty p e,
voltage rati ng a nd c u rre n t rati n g as sp ecified i n t he p arts
list fo r your p ro du ct .
R efer fuse replaceme
n t
to qu
alified service pe r sonn el .
Do N ot O p
erate in E xplosive Atmosp he r es
To avoi d explosio n , do
n
ot op
erate t h is p r o du ct i n an
explosive
at m os ph ere u nless it has b ee n s p ecifically
certifie d fo r suc hop eratio n .
Do N ot O pe r ate Plug-in Un it W it h out Covers
To
avoid perso n al i nju ry, do n ot operate t h is pro duct
wit hout cove r s or p an els installe d . Do n ot apply p owe
r
to
t he p l u g-i n via αp l u g-i n exte nd er .

Do N ot Se r vice Alone
SE
RV
IC
E SA FE TY S UMM
A RY
F O R Q U A L
I F I E D S ERV IC E PER SO NNEL ONLY
R efer also to t he preceding
O p e r ators Safety Summary .
Do n ot p erform inte
rn al service or a dj ustme n t of t h is
p r oduct unless an
ot h er perso n ca p able of re nd eri n g fi r st
ai d a nd res u scitatio n is p rese n t .
U se Ca
r e Wh en Servicing W it h P ower On
Da
n ge r ous voltages exist at several poi n ts in t
h
is p r o
du
ct
.
To avoi dp erso n al i nj u r y, d o n ot to u c
h ex p osed conn ec-
t i ons a nd com po
n
en ts
w h ile p owe r is on .
F G 502
Disco nn ect p ower befo
r
e
r emovi ng pr otective pa n els,
sol d eri n g, o
r re p laci ng
co
mp o nen ts .
P
ower So ur ce
T h is pro du ct is
i n
te
nd ed
to o
p e r ate fr om α powe r sou rce
t h at will
n
ot
a pp ly mo r e t h an 250 volts rms between t
he
supp
ly co ndu ctors or betwee n eit he r s upp
ly
co
ndu ctor
a nd gro u n d . Α pr otective g r o und conn
ect i o n by ωαγ ο f t he
g r o und i n g co n du cto r in t
hep owe r co r d is esse n tial fo r
safe operatio n .

,\\ Μ
ά
'
τίΡσσ ΈR
F G 502 FUN
CTIO N G ENER ATO R
1706-01
REV Α ΜΑΥ 1980

T he F G 502 Fun ct i on Generator is d
esig n ed
to
operate
i nα TM 500 ser i es p
owe r m o du le . It ge n e r ates low
d istortio
n si n
e,
sq ua r e, t r i an gle, positive an d n egative
pu lse, a nd ramp wavefo rm s from 0 .1 Hz to 11 MHz . A
s qu are wave t r igge r is availa b le at t he
fr
o n t panel .
V
ar
i
able
DC offset is also pr ovi ded .
Α voltage-co n t r olle d f r e qu e n cy ( V CF) i np ut co n trols
t heo u tput fr e qu en cy from an exte rn al voltage so ur ce .
T h e
output fre qu en cy can be swept above o r b elow
t he
selecte d f r e qu e n cy to α maxim u m of 1000 :1 de pe nd
i n g
on
t he pola r ity a nd a mp l i t ud e of t
h
e
V
C
F inp ut a nd t he
selecte d out pu t f re qu en cy .
An exte r nal gate i npu t allows t h e ge n erator to o pe
rate
for t h e d uratio n of an exte rn
ally
a p pl
i
ed
gati n g sig n al . T h is
mo d ep
rovides eit he r α single cycle output, o r α t r ai n of
p reselecte d wavefo r ms, de pe nd ing on t he gati n g sig n al
"N%
widt h an d t h e ge n e r ator fre qu en cy setting .
T he var iety of swe p t a nd mo du late d
signals availa b le
fr om t he F G 502 m a k e It es p ecially u seful fo r s uch
ap p licatio n s as testi n g servo-system o r amplifier
res p o n se, d istortio n , a nd stability . It can
b e u se d fo r FM
ge n e r atio
n ,
f
r
e qu
e n cy m u lt i plicatio n , or as α va r ia b le beat-
fre qu ency oscillato r . It can also b e u se d to ge n erate
REV C ΜΑΥ 1980
SPECIFICATION
INTRODUCTION
Ta b le 1-1
Sectio n 1- F G 502
r epetitio n r ates or to neb u rsts . T he square
wave t r igger
output can b e use d as
α so ur ce fo r TT L log i c, o r to
sy
n
c
hr o n ize an exte rn al device su c h as an osc i lloscope or
co un te r .
T h e elect r i cal characteristics
in t h is specificat i o n a r e
vali
d
wit h t he followi ng cond itio n s :
1 . T he i n st r ume n t m u st h ave bee n a dju ste d at an a mb ie n t
tem p e r at ur e betwee n +20 0 C and +30 0 C .
2 . T he inst rum en t
m u st
be
ίη α ποη -co nd e n si ngen vi r o n -
m
e n t
w
h ose li
m its a r e d esc r i be d under En viro n me n tal .
3 . Allow twe n ty mi n utes warm-up time for ope r atio n to
specifie d accuracy ; sixty minu tes after exposure to or
storage In h ig h hum i d ity (co nd e n si n g) en viro
n
me
n t .
Any cond itio n s t h at a r e un i q ue to α p articular
ch a r acteristic are ex pr essly state d as p art of t
h
at
ch aracteristic .
T he elect r ical a nd e nv i r o n me n tal perfor m ance li mits
toget h er wit h t h ei rr elate d vali d atio n proce dur es co
mpr ise
α com p lete stateme n t of t
h
e elect
r i cal a nd e n viro nm en tal
performa n ce of
α calibrate d Instrument .
ELE CT R ICA L C HA R ACT
ER
ISTICS
C h a r acteristics Performance
Re q ui r eme n ts S upp le m en tal I n formatio n
Fr eq ue n cy R a n ge 0 .1
Ητ t ο 11 MHz .
F re qu en cy R esolution
1 part i n 10' of
full scale setti ng
usi
ng FRE Q UEN CY VERN I ER co n trol .
Fr e qu e n cy Sta b ility
< 0 .1% fo r 1 h ou r , < 0 .5% for 24
h
ou rs .
Dial must b e on
calibrate d p ortio na nd
ambie n t te m perat u re must be
25°
C
t5°
C .
Pu lse a nd R a mp F re qu en cy 1/10 t r ia ngle fre qu e n cy .
Dial Ra n ge - 1 to 11
cali br ated . 0 .1 to 1
υη cα 1ί br ate d .

S p ecification- F G 502
Ta b le
1-1 (cont)
REV Β
ΜΑΥ 1980
Ch a r acteristics
P erforma n ce R e q ui r eme n ts S up pleme n
tal Info rm atio n
)ial Acc ur acy < 3% ο of
full scale f r
om
0 .1
Hz
to
1 MHz .
<
5% ο of full scale from 1 MH z
to 10 MHz . 11 MH z setti n g n ot less t han
11 MHz .
3utput
Am p lit ud e > 10 V Ρ - Ρop en circ u it . > 5 VΡ
- Ρ
i n to α 50
Ω load
,
excl ud i n g offset .
R efe r e n ce d at 10 kH z .
k m p lit ud eF lat n ess
Si n
ewave W it h in t 1 .5 dB, r efe r e nce at 10 kH
z .
S q uare a nd tr iangle to si n e- W it h i n
f
3 dB
.
wave am p lit u de
J ffset
Ran ge > + a nd -5 V, open circ u it .
+ a nd -2 .5 V into α 50
Ω loa d .
Si n ewave Distortio n < 0 .5%
ο from 10
Hz
to 50 kH z . H a r mo n ics Dial must be on cali b rate
d p ortion, an d
>-30 d B d ow n at all ot h er
am b ie n t tem pe r at u re must be25*C±5*C .
fre qu en cies .
Tria n gle Sym m etry W it h i n 1 ο / οf r o m 0 .1
H
z to
1 .1
MHz .
W it h i n Dial mu st be on cali br ate d portio n . Ambie n t
3% ο from
1 .1 MHz to 11 MH z u sing 10 6 tem p erat ur e m ust b e 25°C ±5* C .
MUL TI PL I ER setti n g .
Tria n gle
L inearity Within
1 .0%f r om0 .1 H zto110kHz, within
3 ο/ο from 100 kH z to 1 .1 MHz u si n g 10 5
Μ UL TI PL I ER setti n g,wit h in5%from1 ΜΝ
to 11 MHz u sing 10 6 MUL TI PL I ER
setti n g .
S qu arewave and Pu lse O u t pu t
R isetime < 20 n s .
Aberratio ns <
3ο/ ο Ρ - Ρ at full am p litude i n to 50 Ω
load .
P ulse and
R
amp
As p ect R atio
95/5 .
V oltage Co n trolle dF re quency
I npu
t (V
C
F)
R ange
Α 10 V signal sh ifts fre qu e ncy > 1000 :1
w he r e fre q., > 11 Χ MUL TI PL I ER
setti ng a nd fre q~ ; . < 0 .011
Χ
MUL TI PL
I
ER
setting .
Slew Rate
< 0 .5
V
/ μ
s .
E xter n al Gate Inpu t
0 V to
>
+2 V, n ot to excee d +15 V .
B aseline of outp u t wavefor m du ring
off
p erio d wit h i n 500 m
V meas u re d from 0V .
Usable on
t he 10 6 MUL TI PL I ER
setti n g
only
for si n e, t r ia ngle or
s qu a r e waveform o u tput .
Input Im ped an ce
1 ΚΩ .
T r igger O utpu t > 5V o p en
circ u it,
>
2 .5 V into 50 Π
load .
P ower Co nsu m p tio n
Ι
15 W .

Ta
b le 1-2
ENV I R O NMEN TA L C H AR ACT ER ISTICS
Specificatio n - F G 502
REV Β ΜΑΥ 1980
Ta b le 1-3
PH YSICA L C HA R ACT ER ISTICS
C
ha r acte r istics
I n fo r matio n
Tem pe r at u re
O p erating
0°C to 50°C .
Sto r age
-40° C to +75° C .
Altit ud e
O p erating
To 15,000 feet . M axim u m op erati n g
tempe r ature decrease d b y
1°C/100 feet from 5000 to 15,000 feet .
Storage To 50,000 feet .
V i br ation
O p erati n g a
n
d non-operating
W it h t h e i n st ru me n t co mp lete, vib
r ation fre qu e ncy swept from
10 to 55 to 10 Hz
at 1 mi nu te per swee p . V i br ate 15 mi nu tes i n
eac h of t he t hree ma j o
r axes at 0 .015 i n ch total d is p lace m e n t . H ol d
10 mi n utes
at
any
ma j or resonance ; or, if n o n e, at 55 Hz . Total
time,
75 mi nu tes .
S h oc k
O pe
r ating an d non-operating 30 g, 1/2 si n e, 11 m s dur atio n , 3 shock
s in eac hd i r ection alon g
3 m a j or axes, for α total of 18 sh oc
ks .
Transportatio n Qu
alifie d u nd er N ational Safe Tra n sit Committee Test Procedure 1A,
Catego r y ΙΙ .
C h aracte r istics
Dimen sio n s
Overall Size
(meas u re d at maximu m
p oints)
H eig h t 5 .0
i n (12 .7 cm)
W i d t h2
.6 i n (6 .6 cm)
L en gt h 12 .2 i n (31 cm)
N et W eig h t
(Instr u me n t only)
2
I
b s (0 .906
k g)

Ι
I n itial O p eratio n
O
PER ATI N G I N ST RU
CTIO N S
T urn t h e Power Module off b efo
r e i nse r ting t h e pl u g-
i n, ot h erwise, d a
m age may occ ur to t he p l u g-in
ci r cuit r y or co nn ecto r .
T h e F G 502 is cali br ate d a nd rea
d y fo r u se w hen
r eceive d . It is d esig n ed to op e
r ate i n any com p artme n t of
t
h
e TM
500 series p ower m o du le . R efe r to t h e p owe r
mo
du le i n str u ctio n ma nu al for line voltage r e q ui r e m en
ts
and p owe r mod u le o p eratio n . See F ig . 2-1 for
i n stallatio n
removal proce du r e . B e s ur e
t h at t h e F G 502 is f u lly
i n serted i n t h e powe r mod
u le . Pull t h e PWR switc h on t he
power mo d ule . C
heck t h at t h e g r een P OWER lig h t on t h e
F G 502 is on .
T he
Co
n trols a n d Co nn ectors F ig . 2-2 gives
α com
p lete d escri p tio n of t h e f r o n t pa n el co n trols a nd
conn ecto r s .
REV D ΜΑΥ
1980
Fig . 2-1 . F G 502 I n stallatio n a nd r e m oval .
F unctio
n s Available At R ea r Connector
Sectio n 2- F G 502
R efer to t h e rear conn ecto r assig n me n t illust r atio n i
n
t h e M ai n tena n ce Sectio n of t h is
m a nu al for pin
assig n me n ts .
Α slot betwee n p i n s 23 a nd 24 on t h e rear con n ector
i d entifies t he F G 502 as α mem b er of t
h
e
sig n al source
family . Α b arrie r may b e
i n serte d in t h e corres pond i n g
p ositio n of
t h
e p
owe r mo du le j ac k to p reve n t ot h er t h a n
signal
so
urce p lug-i n s f r om b ei n g use d in t h at co mp art-
ment . T h is protects t h e p l u g-i n if s p ecialize d co n nectio n s
a r e ma de to t h at com p artment . Co n s u lt t he Bu ildi n g Α
System sectio n of t h e p owe r m odule ma nu al fo r furt
her
i n formatio n .

Ope rati ng I n str uctio n s-
F
G
502
2-2
O FFSET
Control
Pull and a d just for output
waveform DC offset .
A MPLITUDE
Control
A d justs amplitude of
output waveform .
GATE IN Connector
V oltage applied
permits gating of output
waveform .
V CF IN Connector
CO N TR
O L S A ND CO
NNE CTO
RS
Applied
external voltage
changes output waveform
frequency .
L ATCH
Pull to remove p lug-in
.
T RIG OUT Connector
S quare-wave
output for a pplications
r equiring an
external trigger .
O UTPUT
Connector
BNC connector for
waveform output .
FUNCTION Switch
Selects output
waveform .
VERNIER Control
Allows fine adjustme
n t of output frequency
.
1 Ο
MULTIPLIER
Switch
Sets basic frequency
range .
FREQUENCY Hz Dial
ήνι
υιτι Ριι ε α Ι
1{t°,
105
F ig . 2-2 . Controls and
Connectors .
P
OWER On P ilot
L ight
M ultiply d ial
r eading by MULTIPLIER
setting for
frequency out .

Illuminated when
power is applied to
unit .
REV Β
ΜΑΥ 1980

j
r
L'
O u t pu t Co nn ectio n s
O PER ATI
N GCO N SID ER
ATIO N S
T he out p ut of t h e F G 502 is d esigne
d to ope r ate as α
50 Λ
voltage source wo rk i n g i n to α50 Ω
load . At h ig h er
fre q ue n
cies, an un te ι mi n ated o r im p ro p erly te r mi n
ate d
ou tput ca u
ses excessive abe r ratio ns on t he
outp u t
waveform (see Impe
da n ce M atc h i n g d isc u ssion) . L oads
less
t ha n 50 Λ re du ce t h e wavefo r m
a mp lit u de .
E xcessive distortio no r aber r
atio n s, d ue to im pr o pe r
te
r
mination , are less li k ely to occ ur at
t h e lowe r freq ue n -
cies
(especially wit h si ne a nd tria n gle
waveforms) . To
retain waveform
pur ity, o bse r ve the Iollowi n g pr
eca u tio n s :
1 . U se goo d qu ality
50
Ω
coaxial ca b les and connec-
tors .
2 . M a k e all co n nectio
ns tig h t a nd as s h ort as p ossi
b le .
3 . U se goo d
quality atte nu ato r s if it is n
ecessary to
reduce wavefo r m a mp lit ud
e to sen sitive ci r cu its .
4 . U
se termin ators or im ped an ce-matc
h
i
n gd evices to
avoi d r
eflectio ns w he n u si n g lo n g ca
b les .
5 . En s ur e t h at
atte nu ato r s, te rm i n atio n s, etc
. h ave
ade qu ate powe r h a nd li n g
capa b ilities for t he ou t pu t
wavefo r m .
R ί setime a n
d F allt i me
If t heou t p
ut
p
u lse from t h e F G 502 is use d
to meas u re
t he rise o r falltime
of α device, consider
the risetime
cha r
acte r istics of t he associate
d e qu i p me n t u se d . If t he
r isetime of t h e device
under test is at least
10times g r eater
t han t h e com b i ned r isetimes
of t h eF G 502 pl us t h e
mo n itori ng
osc i llosco pe an d associate d
ca b les, t he e r ro r
i n tro duce d will n ot
excee d 1% . T h is e rr o r
can
ge ne r ally
be
ig n o r e d . Wh en t he r
ise or fallti m e of t he test d evice
is less
t han 10 ti m es as long as
t h e com b i ned r isetimes of t h
e
testi ng system, t he act u
al r isetime of t he d evice m u
st be
dete r mi ned . T h
is is fo und fr om t he ι isetime
of eac h
component ma k i n g
up t he system . T h e total
r isetime
e qu als t hes qu a r e root
of t he sum of t he s qu a r es of t h
e
i nd
ivid u al risetimes . R, = (R,) τ +
(R τ ) τ
+ ( R 3) τ + . . .
Conversely, t h
e
r
isetime of t he device u nd
e
r
test can b e
fo und fro
m th e same relatio n s h i p if t h e act u al
risetimes i n
t h e system
are kn ow n .
T h e
ph ysical a nd elect r ical c h a r
acte r istics of t he pu lse
tra n smitti
ng ca b le dete r mi ne t he c ha r
acteristic im-
REV
Β ΜΑΥ 1980
p e d ance, velocityof
p ro p agatio n , a nd amo
un
t
of sig n al
loss . Sig n al loss is relate d
to
fre
qu e n cy ; therefo r e, α few
feet
of cable can atte nu ate h ig h fre qu
e
n
cy i n for m ation i n α
fast-rise pu lse . It
is im p orta n t to k ee p ca
b les as s h ort as
possible .
Wh
en signal com p ariso n
measurements o r time
d iffe r en ce d eterminatio
ns a r e ma d e, t h e two sig
n als f r o m
t he test d evice sh o u l
d travel t hr o ug h coaxial ca b les wit
h
i d
e
n
tical loss a nd time d elay c h
aracte r istics .
If t h ere is α
DC voltage across t heo u t
pu t loa d , t h e
out pu t pu lse amplit
ud e will b e com p resse d , o r in
some
cases (if t h e voltage
excee d s ±10 V), it may s h
ort
t h
e
o u
tput .
To p r eve n t t h is f r om
occu
r
ri n g, t h e o u tp u t mu st b e
coup
le d t hr
o u g h a 0C bloc k i n g
ca p acitor to t he loa d . T h e
time consta n t
of
t
he co u pling capacitor
a nd loa d m u st be
lo ng eno
u g
h
to m ai n tai n pu lse flat ness .
Impedan ce M atc h i
ng
As t he pulse travels d ow nα tra
nsmissio n li n e, eac h ti m e
it en coun ters α mis m atch , or an impe
d ance d iffere n t than
t h at
of
t h
e tra nsmission li n e, α r eflectio n
is gene r ate d and
se
n t
back along t he line to t h e so ur ce . T h e amplit
ud ea n d
pola r ity
of t
h
e reflectio n s aredete r mi ned by t he
amo un t of
t he en counte r ed im p
ed ance i n r elatio n to t he ch
arac-
te r istic im ped a n ce of t h e
cab le . If t h e mis m atc h im-
p e dan ce
is h
ig
he r t han t he li n e, t he r eflectio n
will be of t he
same pola r ity as t h e
a pp lie d sig n al . If it is lower, t h
e
r
eflectio n will b e of op posite p
ola
r
ity .
If t he reflecte
d sig n al returns before t hep u
lse is e nd ed,
it a dd sto o r s ub tr
acts from t h e amplit ud e of t he pu lse . T h is
d istorts t h e pu lse sh ape a
nd am p lit ud e . If t h e F G 502
is
d rivi ngα h
ig h i m pe dan ce such as t he 1
MO vertical i np ut
to an oscillosco p e, co n
nect t h etra ns m iSsio n lineto α 50 Λ
atte
nu ator, 50 Ω te r mination , an d t h en t h
e osc i lloscope
i n put . T h e
atte nu ator isolates t he input capacita
n ce of t he
d evice, a nd t h
e
F
G 502 is p r op erly te rm inate d .
Α simple r
esistive i mp ed a n ce-matc h i ng n etwo
rk t h at
p rovi d es mi n i
mu m atte nu atio n is ill u strate d in F ig . 2-3
. To
matc h im p eda n ce wit h t h
e ill u strate d n etwo rk , t he follow-
ing
cond itio n s m u st exist :
a nd
R, +
Z2 ) . L2
, +
Ζτ +R τ
OperatingInstructions-FG
502
mu st equal Ζ ,
R, +
Ζ
Ζ
+ R
τ
m
u
st e qu al Ζτ .
2-3

O p e r ati ng Instructions- F G 502
F ig . 2-3 . I mp e d an
ce
m atc h i
n g n etwo rk
t
h at pr ovi d es mi nimu m
atte n uatio n .
T he r efo r e :
or
a nd
T he r efore :
and
R, R τ
=
Ζ ,
Ζτ ; and
R,Z, =
R τ(
Ζτ
-Ζ ,)
R R τ
R τ
R ι =

ΖτΊΖτ - Ζι
)
=
Ζ
,
Ζτ
;T2
-
Ζι
R, =

125(125 - 50) = 96 .8 0
-' 125
=

50
V

=

64 .6 Ω .
125-50
F
o
r
exam p le, to m atc hα 50 Ω system to α 125 Ω system,
Ζ , e qu als 50 Ω a nd Ζτ eq u als 125 Ω .
Wh en co n structi ng suc h α d evice, t he envi r o n me n t
surroun d i n g t he co m po
n
en ts s h ou l d be design ed to
provide α t r ansitio n betwee n t h
eim p eda
n
ces .
T he
ch a r acte r istic i mp ed a nce of α coaxial device is deter-
m i n ed by t
h
e ratio betwee n t he outside diameter of t he
i nn er
cond
u
ctor to t
he i n
side
diamete r
of
t
he o u ter
co
ndu
ctor
D is t he i n si de
d iamete
r
of t
h e
outer co nd ucto
r ,
d is t he
diameter of t h e i nn er co ndu ctor, a nd Σ is t he d ielect r ic
consta n t (1 i n air) .
T h e n etwor k i n F ig . 2-3 p rovi des mi n im u
m atte nu atio n
fo r α p urely resistive im p eda n ce-matc h i n g device . T he
atte
nu
atio n
as see
n
from o n ee nd does not e qu al t h at see n
fro m t he ot h er e nd . Α signal ( Ε ,) a pp lied from t he lower
im p
eda
n
ceso ur ce enco un ters α voltage atte nu ation ( Α ,)
t h at
is
greater t h
an
1
a nd less t h an 2, as follows :
Asig n al (
Ετ )
a pp lied f r om t he h ig he r impe d a n ce so ur ce
( Ζτ
)
en counters α greate r voltage atte nu atio n (
Ατ )t
h at is
g r eate r t h a n 1 a nd less t
h
an 2(
Ζ τ / Ζ ,) :
In t he exam p le of matc h i n g 50 Ω to 125 Ω ,
a nd
Ατ
Αι = Ε ,

=

R,

+
1
Ετ Ζτ
(z .
=
138 Ιο g ιο D/ d ) .
Ετ
R
ι
Αι

__

125

+

1 = 1 .77
Ατ

64 .6
+__
96-8

950
6-8
+
1 =
4 .43 .
T h e illust r ate d n etwo rk
can
b
e mo d ified, to p
r
ovi d e
d iffere n t atte nu atio n r atios, by ad ding an ot h er
resisto
r
(less t han R,) b etwee n Ζ , an d t h e jun ctio n of R, an d R z .

F
ree-
R u nn i ng Out pu t
Set t he A MPL
IT
U
D E
co
n t r
ol
f u lly cloc k wise, and ma ke
certai n t h e O FF SE T co n t r ol is pu sh ed in . Set t h e FUNC-
TION selector to t h e d esi r e d wavefo r m . See F ig . 2-4
.
Select t he d esi r e d f r e qu e ncy wit h t h e
MUL TI PL I ER a nd
FRE Q UEN CY H zd ials . N ote t h e ramp a
n
d p ulse
fr e qu e n-
cies a r e one-te
n t h t h
e
FRE
Q
UEN CY H z an d MUL TI PL I ER
dial
setti n
gs .
T heou t pu t frequency is cali b rate d w he n t he
FRE
Q
UEN CYVERN I ER co n trol is i n t he f u ll cloc kwise
p osition . Connect the loa d to t he O U T PU T con n ectora nd
a dju st t he A MPL IT U D E co n trol fo rt h e desi r ed ou tp u t
am p lit ud e . Pull a ndad j ust t h e O FF SE Tco
n
trol to
positio n
t he DC level
(
b aseli
n
e) of
t h e o u t p ut waveformabove o r
b elow 0V as desi r e d .
Gated Out p ut
Α gati ng signal of at least 0 V to +2 V a pp lied to t he
GAT E IN connector p r ovi d es gate d wavefo
r
ms .
T h
e
du ratio n
of
t h e
out
pu t waveforms d epe nd s upon the
du ratio n of t he gati n g sig n al . T he n umbe r of cycles du ri n g
t he bu rst d e pe nd s upon t he FRE Q UEN CY H z a nd
MUL TI PL I ER d ial setti n gs . Si n gle cycles ca
n
be obtai
ne d
by
a pp lyi ng α gati ng sig n al wit hαperio d a p p roximately
e qu al to t h e period of t he F G 502 o u t p ut . T h e nu mbe r of
cycles p er bu rst may b ea pp roximate d by d ivi d ing t he
gati ng sig n al dur atio n byt h e pe
r
iod of
t he F
G
502
o
u t pu t .
Fig . 2-4 . Outpu t wavefo r ms availa b le from t he F G 502 .
O u t pu t fre q ue n cy can be varied du ri n g t he burst
du ratio n by applyi ng t h e proper voltage to t h eV C F IN
co nnecto r . See V oltage-Co n trolled F re q ue ncy (V C F) Out-
p u t followi ng .
OPERATION
Ope r ati
ng I
n st r uctio n s-
F
G 502
V oltage-Cont r olled Fre q uency (V C F) Outp u t
The out pu t fre qu e ncy of t he F G 502 εαη b e swe p t ove r α
fre q uency
range
of
1000 :1, d epe nd i n g on t h e MUL T-
I PL I ER setti n g, b ya pp lyi n g α0 V to 10 V signal tot heV C F
IN connector . It maybe n ecessa r y to va r y t he CA L co n trol
to o b tai n t he f u ll 1000 :1 swe p t r a n ge or t he lowest swe p t
fre q ue
ncy d esire d . See F ig . 2-5 for maximu m V C F ra n ge
for eac h MUL TI P LI ER setti n g .
Ο
z
ω
ω
Ο
z
α
¢
α
ω
J
10 6
10 1
1W-
10 1 -
10 1 -
10 1 -
1
Σ
10 -ι
IL
11 k H z

11 MHz
1 .1 kH z

1 .1 MHz
110 Hz

11 0 kH z
11 Hz

11 kH z
1 .1 Hz

1 .1 kHz
0 .11 Hz

11 0 Hz
0 .11 Hz

11 Hz
0 .11 Hz

1 .1 Hz
10 - ι 1 4 10 2 10 3 10 6
10 3
10 6 10'
FRE Q UEN CY Hz
170&05 Α
Fig . 2-5 . G r aph sh owi ng r ange of fr equen cies fo r each
MUL TI PL I ER setti ng t h at can b e swe p t wit hα0 to 10 V sig n al
app lied to t he V C F Input .
T he polarity of t he V C F in pu t sig n al d etermi nes t
he
d i r ectio
n t heo u t pu t f r e qu e ncy is swe p t from t hef r equen-
cy set by t h e MUL TI PL I ER, FRE Q UEN CY H z, a nd VER-
N I ER cont r ols . Α p ositive-goi n g voltage r aises t he fre-
que n cy, w h ile αnegative-going voltage lowe r s t he fre-
quency . Α voltage t h at va r ies symmet r ically about 0 V
swee p s t he out pu t f r e qu ency symmetrically abo u t t he
center fre quency d etermi ned by t
h
e f r e q uen cy con
trols .
See F ig . 2-6 .
Si
n
ce
t h e V
C
F in pu t am p lit ud
e
vers us f r e qu e n cy is α
linear relations h i p , t he fre quen cy outp ut r an ge may be
dete r mi ne d f r om t he V C F in pu t amplit ud e . R efer to t he
following test un der t
he h
eadi
ngR
esp o nse A
n
alysis for α
ty p ical applicatio n usi ng t he V C F feat u re .

Ope r ati ng I
n str u ctio n s- F G 502
VC F IN
O UT PU T
VC F IN
S WE PT FRE Q UEN CY
RAN G E
(s)
O UT PU
T
1706-DOA
R es pon se A n alysis
Fig . 2-6 . Swe p t Fr e que
n cy r ange wit h 10 V sig n als a pp lie d to
VCF
IN
Co nn ecto r .
Th e F G 502 is p a r ticularly s u ited for
dete rm i n i ng
res po nse c ha r acte r istics
of circuits o r systems . T h is
a pp
licatio n u tilizes t he V C F i npu t of t h e F G 502 to
swee p
t he ge ne r ator over α ra n ge of fre qu en
cies . Βγ ap p lyi n g t he
desi r ed wavefor
m fr om t he F G 502 to αdevice u nd e r test
a nd sweeping
t he wavefo r m f r equen cy over α selecte
d
ra n ge, various r espo n se ch a r acte
r
istics
can be ob se r ved
on α mo n itori
ng oscilloscope .
T h e following pr oce
du re d esc r i b es α tec hn i qu e for
dete
r mi n ing res p o nse ch a r acteristics of any fre q ue
n cy
sen sitive device t h at o pe r ates
wit h i n t h e fre qu ency ra n ge
of t h e F G 502 . R efer to
t he V oltage-Co n trolled F re qu e n cy
(V C F) O utpu t d iscussio
n under Operatio n fo r add itio n al
i n formatio n .
1 . Co nn ect t h ee qu i pm ent as s h ow n i n F ig . 2-8 .
2 . Set t he MUL TI PL I ER selecto r and FRE Q UEN CY Hz
d ial for t he d esi r ed u p per o r lowe rf r eq ue ncy
limit
A PPL ICATIO N S
(d e pe nd i ng on
t h e d i r ectio n you wis h to swee p ) . See
F ig .
2-5 for V C F ra n ges an d MUL TI PL I ER
setti ngs .
3 . Apply
the d esire d wavefo r m to t h e VC F 1 Ν
connec-
tor .
4 . A dj ust t he amplit ude of t he V C F i np ut
waveform for
t he d esi r ed outp ut f r eq ue
ncy
ra
n ge .
5 .
O b serve t he res po nse ch aracte
r istics
on
t he
m onitori ng oscillosco pe .
T he fre qu e ncy
at w h ic hαd isplayed r es p onse
cha r acteristic
occu r s can be d etermi n ed by
r emovi n g t h e
V C
F i npu t waveform, t hen ma nu ally a
dj usti n g t h e FRE-
Q
UEN CY Hz d ial to agai
n
ob
tai nthe p artic u lar
ch aracteristic obse
r ve d in t he swept display . R ead
t he
fre q ue ncy on
t he FRE
Q
UEN CY Hz d ial .

Fig . 2-7 . Ph ase r elatio ns h ips b etween vario us OU T PU T wave-
forms a nd t h e TR IG OU T wavefo r m .
TR IG OUT
W A VEF ORM
TR IA NG LE
W A VEF ORM
SI NE W AVE
SQ UARE W A VE
TR IG O UT
W A VEF ORM
RA MP
W A VEF O
RM
PULSE
W A
VEF
ORM
D U TY CYC LE Ο F ΤΗΕ TRIG O UT
W AVEF ORM F O LL O W S
THE
DU
TY CYC LE O
F
THE
O
U
TP UT W A VEF O RM .,
7 os- zτ ~
Fig . 2-8 . A n alyzi n g ci r cu it o r system r es p o n se .
Ope r ati n g I n st ru ctio n s- F G 502
To n e- B urst Gene r atio n o r Ste pp e d F re que n cy
M ultiplicatio n
T heF G 502 can b e u se d as α to ne-bu rst ge n erator o r
fre qu ency m u lti p lie r for chec k i n g
to
n
e-co
n t r
olle
d
d evices . T h is a pp licatio n u tilizes α Pu lse Ge n erator (s uc h
as t he Te k tro n ix P G 501) as α gati n g sig n al so urce a nd α
R amp Ge n erator (s u chas t he Te k tro n ix R G 501) as α V C F
signal so urce .
T he followi ng proce du re d esc r i bes α tec hn i que for
o b taining α tone-burst or fre q ue n cy m ultiplied output
from t h e F G 502 . R efer to t he Gate d ( Bu rst) O u tp u t a nd
t he V oltage-Co n tr olle d Fr eque n
cy (V C
F) O u tput d
is-
cu ssio ns un der O pe r atio n fo r a dd itio n al i n formation .
1 . Co nn ect t h eequ i p me n t as sh
ow
n i n F ig . 2-9 .
2 . Set t he R amp Ge n erator for t h e d esire d r am p
d uration an d polarity .
3 . Ad ju st t he Pu lse Ge n erator pe r io d for t he d esired
nu mber of bu rsts
with i
nthe selecte d r am p du ratio n .
Ad ju st t he Pu lse Ge n erato r d uratio n for t he d esire dbu rst
wi d t h .

Operating I n st
r uctio n s- F G 502
VC F IN*
GAT E
IN* ;
TONE-BURSTOR
ST
EPPE D FRE Q
UEN CY
O UT PU
T
ιι
* GATI N G PUL SE SY
N C HR ON IZ E D
W IT HV C F R A MP .
ι
1708-
ΟΘΑ
4 .
Select t h e swee p f r equen
cy range
by a dj usti ng t he
FRE Q
UEN CY Hz dial
for one en d of
t he swe p t r an ge
( up per or lowe r
limit de p en d i n g on
t h e pola r
ity of t h e
r amp) . T hen
ad ju st t heR amp
Ge nerato r amplit
ud e for t h e
ot he
r swe p t fre qu en cy
li m it .
Fig . 2-9 . To ne b
ur st gene r atio n o r
ste p
pe
d f r e qu en cy mu
lt i pl i cat i o n .
Ot h er to
n e- bu rst o r
fre qu en cy multi
p lie d c h ar-
acte r istics can
be ob tai ned by
usi ng d iffere
n t gati n g i n p
u t
waveforms, i .e ., tria
n gle, si n e, s qu
are, etc .

WARNING
THEFOLLOWING
SERVICING
INSTRUCTIONS
ARE
FOR USE BY
QUALIFIED PERSONNEL
ONLY . T O
AVOID
PERSONAL INJURY, DO
NOT PERFORM
ANY
SERVICING OTHERTHAN
THAT CONTAINED
IN
OPERATING
INSTRUCTIONS UNLESS
YOU ARE
QUALIFIED TO DO SO .

Introduction
T he t r ia n gle wavefo r m is t he b asic waveform
i
n
t h
e
F G 502 . The ram p waveforms a r e tria
ngle wavefo r ms wit h
non-equal
runup a nd r u n dow n ti m es . T h e si ne wave is
de r ived from t h e triangle waveform, u si ng α fo ur-ste p
a p p r oximatio n . T h e s qu are a nd pulse waveforms are
ge ne r ate d by t he tr ia n gle ge
n e r ator co n trol circuitry .
Refe r to the simplifie d f loc k Diag r a m a nd
t he
ci
r cu it
d iagrams i n
t h
e pullout
p ages of t h is ma nu al, along wit h
t
h
e
followi n g d isc u ssio n , fo r α com p lete u nd e r sta nd i ng of
t he F G 502 operatio n .
Tria n gle Ge n erator (Diag
r
am
1)
Ope r atio n al a mp
lifier
U 140,
0140, a nd
t
he p ositive
timi ng r esisto
r
s
for m α p ositive co n sta n t cu rrent sou rce .
U 175, 0175, a nd t he n egative timi n g resisto r s fo r m α
n egative co n sta n t cu rre n t so ur ce . T h ese co n sta
n
t cu rr e
n t
so u rces supply t he c urr e
n t (eit h er p ositve o r n egative) to
ch arge t
h
e
timi
ng ca
p acitor, ge n erati n g t h e tria n gle
wavefo r m .
To und e r sta nd t heope r atio n of t h is circuit, assu me t he
jun ction of CR 140 a nd C R 170 is positive wit h r espect to
g r o un d . C R 140 is off a nd C
R 170
is con
du cti ng . CR 175 is
off, an
d
t he
ca p
acito r is c h a r gi ngfro m t h ep ositive c ur rent
sou r ce t hro u g h C R 145 . Q292 is off, a nd t he j un ctio n of
C R 140 an d C R 170 is h el d at ap pr oximately
5 V above
gro und . T h is is d o n e b y C
R 300, CR 304,
C
R 308 a n d CR 312 .
Cu rr en t to h ol d t he ju nctio n of CR 140 a nd C R 170 p ositive
is s upp lie d by R155 from t he +17
V
s upp
ly .
In t h is state C R 248 is on, C R 245 is off, a nd t h e voltage
level at t h e b ase of Q230A ( n ot co ndu cti n g) is
set b y t he
c u rr en t flowi n g t
hr
o
u g hR 245, C R 246, a nd R 240 .
T he ram p , movi ng i n αp ositive directio n
,
a pp
ears at t h e
b ase
of
023013 t hr
ou g
h t h e action of so urce follower Q200
a n d its consta n t cu rre n t sou r ce 0202 . Q204 and Q210,
compleme n ta ry emitte r followe r s, dr ive t he AC com pe
n-
sate d
attenuato r (
R T224, C224, an d R220) .
Wh e n t he
base of Q230 B (nowco nd ucti
n g) reachest he
same voltage as t he base of 0230 Α (0230 Α a nd 023013
form
α com p arato r ) Q230 B stops co ndu ctio n a nd Q230A
t u r ns
on .
T h e
collecto
r
of Q230A goes p ositive,
t u r n i n g
0292 on a nd Q290 off . T h e collector of Q292 goes
REV Β ΜΑΥ 1980
T HE O
R Y O F O PER ATIO N
Sectio n 3- F G 502
n egative, limite d to a b o u t -5 V by
d iodes
C
R
302,
C R 306,
C R 310 a nd C R 314 . T
h
is
act i on tur n s d io d es CR 248 a nd
C R 246
off, setti n g t he level at t h e base of 6230 Α slig h tly
below
g r o und . T h e negative voltage at t he jun
ction
of
C R 140 and C R 170 t urns C
R 175
on
a nd C R 170 a nd C R 145
off . T h is action
d
isco
nn
ects
t he p ositive cu rre n t source
f r om t
h
e
timi ng ca p acitor a n d con n ects t he n egative
c u r r ent so u rce t hro ug h C R 175, ca u si n g
t he r am p to go in
t he n egative d i r ectio n .
T h
e
act i o n co n tin ues un til 023013 is
t u r n ed on ( by
t he n egative ram p at its b ase) a nd t he cycle
is
r
epeate
d . R250 sets t hevoltage at t h eb ase of 0230 Α a nd
t h ere by t he DC level of t he triangle
waveform .
T he fre qu en cy of t h e tria ngle wavefo r m is co n t r olle
d
by
two factors : (1) t he val ue of
t he timi n g ca p acito r , and (2)
t he amou
n t
of
cu rr e n t available to ch arge It . T he curre n t is
va
r
ie
dby ch an ging t h e val u e of t h e ti m ing resisto r s (t
h
e
la r ger t h e val ue of t he timi n g r esisto r sa
n
dcapacito
r s, t he
slowe r t he r ate of rise), a nd t h e voltage ac
r oss t he timi ng
resisto r s .
T hevoltageacross t he timi ng r esistors
is essen tially t he
voltage at pi n
3
of
operatio n al am p lif i er U 140 in t he
p
ositive cur rent sou r ce, a nd U 175 i n t he negative c urr e n t
so u rce . T he voltage at pin 3 of U 140 is co
n t r olle d by
su m mi n g am p lifie
r
U
135
.
T h e voltage at p i n3 of U 175 is
co
n trolle d by summi n ga mp lifie r U 170 . I np ut voltage to
t h ese summi ng am p lifie r s is co n t r olle d by t he
FRE-
Q UEN CY Ητ d ίαΙ t h ro ugh U
100,
o
r t h e voltage at t h e V C F
IN fro n t p an el conn
ector . Wh e n t h e voltage at pi n 3 -of
U 100 goes mo r e pos i tive b y increasing t h e
F R
E Q UEN CY
H z d ial setti n g, or t h ro u g h t h e V C F IN
i
np
ut, t h
e
voltage at
p i n6 of U 140 goes negative
a nd pin 6 of U175 positive .
T
h is
actio
n inc r eases t he voltage ac r oss t he timi n g
resistors . T he values of t he timi ng r esistors a nd timi
ng
capacitor a r e selecte d by t he
f r
on
t p
an el
MUL TI PL I ER
switc h . R170 im p roves low
f r eq uency symmet r y b y co m -
pe
n sati n g for b ias c
ur re
n ts i n t he operatio n al a mp lifiers
w h en operati n g at low levels . V oltage le v els t h ro u g h t
h
is
ci r cu it a r e0 to abo u t
+10
V at
t h
e
i npu t of
U
100 . T h is is
tra n slate d at a b
o u t +7 V to +17 V at pi n6 of U 135 .
During non-gated o p eration,
t h
e base
of Q332 is two
d
io
de dr ops above g r o und . 0332 is off a nd Q330 is
cond u cti ng . Q325 is on a nd Q315 off, b ac k b iasi n g CR 315
a nd allowing no r mal o pe r atio n of t
he tria ngle ge n erator .
Wh e n t he p ro pe
r level gating sig n al is applied tot hef r o n t
pa n el GAT E IN conn ector , t h e base of Q332 alte rn ates
wit h t he gati ng sig n al . Wh en t
h
e gati
n g sig n al is low
(gro und pote n
tial) Q332
co
ndu cts . T h is actio n ca u ses
co
ndu ctio n in Q315 a nd fo r war db iases C R 315 . T h is locks
t h e ju nctio n of CR 140 an d C R 170 at t he
level
set b y
R155,

T h eo r y of O p e
r ation- F G 502
causi
n g t h ese d iodes to con du ct
t h e timing capacitor
c h argi n g curre n t to grou
nd th ro u g h Q315 . O p e r atio
n
of
t h e tria n gle ge
n
e
r ator is i nh ibite d b y t h is actio n . Wh e
n t h e
gati n g signal goes
positive, C R 315 is bac k biase
d an d th e
ge
n
erato
r f un ctio n sn ormally .
R am p wavefo r ms are ge n e
r ate d by c h a n gi n g t h e value
of either the
positive or n egative timing r esistor to create
different rise
and fall times .
The square
wave that controls charging of
the timing
capacitor is picked off at the collector
of Q290 and
operates the trigger o ut
amplifier . The impedance looking
into the emitter of
Q268 is about 51 Ω . T he same
waveform
operates the
isolation diode bridge CR260,
CR262,CR264,
and C R266 . The output from
this bridge is the square or
pulse waveforms . The triangle
waveform (to the output
amplifier a nd
sine shaper) is taken from the
emitter of
Q210 .
Sine Shaper
(Diagram 2)
T his circuitry d erives αfour
step a pproximation of α
sine wave from the triangle
waveform b y use of α
diode
ladder configuration
. This circuit consists of four
bridges .
All i nputs toth
ese bridges are connected
to R 350, and all
outputs are connected to
their common load resistor
R 395 . E ach
bridge . i s supplied by current from
the +17 V
a nd
-17 V supplies through
different value resistors,
R 358, R 368, R 378, R 388andtheirequal
value complemen-
tary r esistors in
t
he
n egative supply leads .
As the triangle
waveform increases in voltage, each
b ridge reaches α c
urrent limit whereby it can no
longer
i ncrease current
through load resistor
R 395 . These
current limits are set by R 382,
R 384, R 388, in one bridge
and similar r esistances
for the other bridges . R 350
and
R250 are set for
minimum sine wave distortion
.
Sine W ave B uffer
T his circuit
operates as an inverting
operational
amplifier,
with α gain of about four . The
sine wave output
from
the shaper is fed to the base
of Q400 . Α n egative-
going signal at the b ase
of Q400 causes its
collector to go
p ositive and
the collector of Q410 n
egative . The collectors
of
0420 and Q430 respond in
the opposite p olarity . Q440
inverts the waveform at
the collector of Q420,
and t he
bases of Q442
and
0444
are d riven in
phase . Output and
n egative
feedback a re taken from
the j unctions of R 442
and R 444 . R 450 in t he n
egative feedback loop sets
the DC
gain and C450 sets
the AC gain .
Out p ut Amplifier (Diagram
3)
T his circuit
operates as an inverting operational
amplifier . The
selected waveform is applied to
the base of
Q480 through A MPLITUDE control
R 465 . Q480 and Q490
operate as an emitter-coupled
amplifier . The collector
of
Q480 drives the base of
0500 . The b ase of
0515 is d riven
by the collector of Q500 . The collector of
Q490 d rives the
3- 2
b ase of Q506 . T h e p ola r ities a r es
u c h th at th e collecto r s of
Q515 a n d Q506move in ph ase .
T h eir collectors d r ive th e
o u tp ut stage
(Q530, Q532,0540, a n d 0542) .
T h e b y p ass-
ed
resisto r s i nth e emitter ci r c u it of
th e o ut pu t tra n sistors
limit t h eo u tp ut c ur re
nt . R 550, R 552, R 555,a n d
R 556
provide α b ac
k termi nation of 50 Ω . N egative feedbac
kis
ta k e n from t
h e jun ction of th ec ur re nt limiti
n g resistors i n
t he
output stage . R 566, in t he feedback loop,
sets the DC
gain w hile C566 and
C568, adjust the AC gain . R 475,
the
OFFSET control,
p laces an adjustable DC
bias
on
the
input of
the amplifier to change the amplifier
output level .
P ower Supplies (Diagram
4)
Diode bridge
CR600 r ectifies 25 V AC from
the power
module .
The full wave rectified DC is
filtered by C602 and
a
pplied as r egulated +20
V DC to the circuitry in t he
F G 502 through t he series
p ass transistor located
i n t he
p ower module
.
VR610
sets the voltage at p in 3 of U
615 . U 615 has α gai η
of
approximately three . The
output at p in 6 therefore, is
about
20 V . E mitter
follower Q620 drives the base
of the
series pass transistor
. Should t he+20 V load
increase, pin
2 of U 615
(through R623 and R625)
goes n egative . This
causes p
in 6 to go p ositive, increasing
current flow and
restoring
the +20 V to its
previous level . Should
t he
current drawn increase
so the voltage across
R 632 is
sufficient to
turn 0622 on, current
limiting occurs . 0620
reduces
conducting, reducing
the current through t he
series pass transistor to α
safe level . CR632 p rotects
the
+20 V supply,
if it should s hort to the
m inus supply .
U 664 is an
operational amplifier with αgain
of about
one . The r
eference voltage is the +20
V a pplied t hrough α
divider at pin 2 . The output
at p in 6 (-20 V) drives
emitter
follower 0662 .
Q662 drives the series p
ass transistor
located
i n t he p ower module .
Current limiting takes p lace
when current through
R655 turns Q660 on . F
eedback
occurs through R678
. The action of this circuit
is similar to
the +20 V
regulator . CR655 protects
this supply should α
s
hort occur to -20 V .
The
+17 V is referenced to the
+20 V . U 635, with α gain
of
about one, controls 0635,
the series p ass transistor
for
this supply . F
eedback occurs at pin 2 of U
635 . Current
limiting
in the +20 V supply p rotects
this circuit .
The -17 V supply
is compared to the
+17 V at p in 2 of
U 650 .
The gain of U 650 is about
one . Q650 serves as the
series p ass transistor for
t his supply . F eedback
occurs
through R640 .
Current limit for this supply
is the -20 V
s upply
current limiting .
The r egulation
of the +17 V and
-17 V s upplies is
similar
to that in the 20 V supplies
.
REV C ΜΑΥ 1980