Tektronix sg 502 User manual

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Te
k tro n i x ,
Inc .
Ρ . Ο . Box 500
B ea v erto n , O r ego n 97077
T EK TR
O
N
IX°
SG 502
OSCILLATOR
I N ST R U CTIO
N M A N U A L
Serial N u m be r
070-1430- 0 1

1176

REV . Β
NO V 197 6
S E CTIO N 1
S E CTIO
N 2
W A RN ING
TA
BLE
O
F
CO
N T EN TS
T he r
emai
n i ng portion o f t h is Table of Co n te n ts
lists servici ng Instr u ctio ns
t h
at
expose p e r so nn el to h azardo u s voltages .
T h ese Instructio ns a r e for
qu alifie d service pe r sonnel o n
ly .
CHANG
E I NF O RM ATIO N
SG 502
ί
S
E
CTIO
N 3 AD JUST MEN T
3-1
S E CTIO N 4 M AI N
T
EN
ANC E A ND I NT ERF ACI N G I NF O RM ATIO N
4-1
SE CTIO
N
5CI
R C U IT D E SCR I PTIO N
5-1
SE CTIO N 6
REPL AC EABLEELE CT R ICA L P AR TS L IST 6-1
O PTIO N S
SE CTIO N
7 DIAG R AMAND CI R CU IT B OA R D I LLU ST R ATIO
N 7-1
SE CTIO N 8
REPL
AC
EABLE MECHA N ICA L P A R TS L IST
8-1
AND EXPL OD ED V I EW
P age
O PER ATI NG
I N
ST RU
CTIO N S 1-1
S PE CI F ICATIO NAND PERF O
RM
A
N
C
E
C
HEC K 2-1

Fig . 1-1 . SG
502 Oscillator Plug-in Module
.

Th e SG 502 ge n erates low d istortion si n e
waves and
s qu are waves ove r α f r eque n cy r a n ge of 5
Hz to 500 kH z . Α
stable RC oscillato
r p rovides 5 V r ms out pu t u nder no
loa d , o
r 2 .5 V rms i n to α 600 Ω load . Α co n ti n uo
u sly-
variable co n trol affo rd s greater t h an 40 dB
sine-wave
attenuatio n in a dd itio n to pus hbutton -selecte
d 10, 20, a nd
40 dB steps . Α 0 to +5 V fixed am p lit u desqua
r e wave, at
t h e same freq u en cy as t h e si ne wave, is
available from α
sep a r ate fro n t pan el co nnector .
T h
e SG
502 also featu r es
an exte rn al sync in pu t w h ic
h loc ks t h e out p ut fre qu en cy to
Installation
and R emoval
T urn t he P owe r M
odule off before inse r ti ng t he plug-
in ; ot he r wise,
d amage may occu r to
t h ep lug-in
ci r cuit
r y .
REV
. C N O V 1976
IN ST RUMEN T
D E
SC
R I P TIO N
PREP A R ATIO
N F
O
R U S E
F ig . 1-2 . Plug-In M o du le Installation/removal .
Section 1-SG 502
O PER ATI N G
I N
ST
RU CTIO N S
α sync h ro n izi n g
sig n
al
. Α si ngle d ial a nd five decade
p us hbu ttons p
rovide fre quen cy selectio n .
T he elect r ical ch a r acteristics a
r
e
vali d
only
if t he
SG 502 is cali b rated at an am
b ie n t tempe r at u re betwee n
+20° C a nd +30° C and op
e r ate d betwee n 0° C a nd+50° C,
unless ot
herwise n oted . T he outp u ts must be terminated
i
n 600 Ω loads .
R efe r to F ig .
1-2 . C heck to see t h at t he plastic barriers
on t he i n terconnecti
ng j ac k of t h e selected P owe r M odule
com p art m en t matc
h t h e cut-outs i n t he SG 502 ci r cuit
boa r d edge
co n nector .

Operating Instructions-SG 502
VAR AMPLITUDE
0 to > 40 dB
attenuation
continuously variable
.
Square-wave
output BNC
connector .
SYNC INPUT
Connect to external signal
source for synchronization .
Sine-wave output BNC
connector .
STEP ATTEN
Calibrated
attenuation steps .
Fig . 1-3 . Front panel controls and connectors .
POWER
When lit, indicates power
is
applied .
FREQUENCY Hz
Calibrated from 0 .5 to 5.0
.
Selects frequency in con-
junction with MULTI-
PLIER .
MULTIPLIER
Multiply FREQUENCY Hz
dial setting by active push-
button to obtain output
frequency .
1430-03
REV .
C
NOV
1976

Alig n t h e SG 502 c h assis wit h t h e upper an d lower
guides of t he selected com p artme n t . Pu s h t he mo dule in
a nd press fi r mly to seat t h e circuit boa r d i n t he i n te r-
conn ecti n g j ack .
To r e m ove t he SG 502, pull on t he release latc h , located
i n
t
he
lowe
r left
corn
e r ,
un til
t h
e
i
n terco n necti n g j ack
d ise n gages an d t he SG 502 will sli d e ou t .
Apply p ower to t he SG 502 b y p
ulli n go u
t
t he powe r
switch kn
o
b
of
t he P owe r M od u le .
M ak i ng Con n ectio n s
F ig . 1-4 s h ows an
eq uivalent ci r cuit fo r t h e 600 Ω sine-
wave an d s q ua
r e-wave out p uts of t h e SG 502 . Α 50 Ω
coaxial cab le adds abo u t 30 pF per foot to t h e output
.
U se
sh ort cables to avoi d reduced si n e-wave am
p lit ud e an d
roun ded square waves, especially at
h ig h er fre q ue n cies .
Sync
hr
o
n
izatio
n W it h an E xter n al Device
To
sy nc h ro n ize t he SG 502 wit h an exter n al oscillato r ,
p lug t he si n e-wave outp u t of t h e exte rn al oscillator
i n
to
t he SY N C I NPU T j ack on t h e front p a
n el . Attem p ti ng
sy nc h ro n izatio n wit h ot h er t
h
anα si
n e-wave may cause
h
a
r
mo
n ic d istortion of t h e SG 502 o u tp u t . M axim u m
pur ity is obtained wh en bot h signals a
r e t h e same
fre q ue ncy .
T h e f r eque n cy range over w h ic h t h e syn c h ro n ization
occurs de p ends upon t h e
amplitude
of
t h e syn c h ro n izi n g
signal .
T he voltage
req
u ire d fo r syn c h ro n izatio n varies
li n early f r
om
0 V (when t he fre qu e n cies are i d e n tical) to
a pp roximately 5 V rms (w hen t h e f r eq uencies diffe
r
by
5 ο/ο ) .
A pp roximately α
1 V ρ - ρ si n e wave at t he oscillato r
fre q ue ncy is available from t he SY NC I NPU T conn ecto r .
Th e sou r ce im p eda n ce is 10 k Ω .
REV . C
N O V 197 6
Co
n trols
an d Co nn ecto r s
R efer to F ig . 1-3 . Eve n t h o u g h t h e
SG 502 is
fully
cali brated an d r ea d y to u se, t he f un ctio ns an d actio n s of
t h e cont r
ols a nd conn ecto r s sh ou ld b e r eviewe d befo r e
attem p ti ng
to
u
se it .
Note
t he ST EP ΑΤΤΕΝ pu s hb utto ns
a r epush -p ush actio n
s,
w h ile all t h
e r est a
r
e self-
ca n celli n g actio ns . N ote also t h at t h e P O WER lig h t is t he
only visual i nd icatio n t h at t h e p owe r is b ei n g a pp lied to t he
SG 502
.
O PER ATI N G CO N SID ER ATIO
N
S
Sy nch ro n izing an E xter n al Device
T h e +5 V s q uare-wave o u t pu t can be used to syn
-
ch ronize an exte r nal d evice suc
has α
coun
te r o r os-
cilloscope :
T h e s qu are-wave am p lit ud e will be +5 V ope n-
ci r cuited, and will d ecrease as t he loa d im ped an ce
decreases .
O p
e r
at
i ng I n str u ctio n s-SG 502
600 Ω
F ig . 1-4 . Eq uivale
n
t
600 Ω ou t pu t ci r cu its .
1 α 3ο - οα

Ope
r ating Inst ru ctions-SG
502
REPAC K AGI N G
F
O
R S H I PMEN T
If t
h
e
Te k tronix i n strument is to
be s h i p pe d to α
Te
k tronix Service Ce n ter for
service or re p air, attac h α tag
sh owi n g : owner
(wit h ad dress) a nd t
he n ame of an
i n dividual at
your firm t h at can be co
n tacte d , com p lete
i n
str u me n t serial num ber an dα d
escriptio n of t h e service
re q uire d .
Save a nd re- use t h e pac
k age i n w h ic h your instrument
was sh i pp ed . If t h e
original p ac k agi ng is
unfit for use or
n ot available,
repac k age t he i n str u me
n t as follows :
1 . O b tai n α carto
n of corrugated cardboar
d h avi ng
i n si d e dimensio nsof no
less t han six i n c hes
more t han t h e
i n strume n t dime
n sio n s ; t h is will allow for
c ush io n ing .
R efe
r to t h e following table for
carto n test st r ength
re q uirements .
2 . Surrou nd t he
instrume n t wit h p olyet h yle
n e
sh eeting to
protect t he fi n is h of t h e instrume
n t .
3 . C us h io n t h e i n str
u ment on all sides b y
tig h tly
pac k i n g dunn age
or uret h ane foam b etwee
n carton and
i n str u me
n t, allowi n g t hree inc hes on
all si d es .
4 .

Seal carton wit h s h
i pp i n g ta p e or i n dustrial stapler
.
S
H I PP I N G CA R TO NT E STST
REN GT H
G r oss W eig h t (I b ) Ca
r to n Test St r e n gt h (lb)
0-10
200
10-30
275
30-120
375
120-140
500
140-160
600

S PE CI F
ICATIO N
S
Table 2-1
E lectrical C h aracte
r istics
Section
2-SG 502
S
PE
CI
F ICATIO N
A N D
PERF O
RM A N
C
E C HE C K
I n troduction
T h
is p roced
ur
ec
h eck s t he electrical ch aracteristics of
t he SG 502 t h at appear in t he Specificatio n . If t he
i n st r ume n t fails to meet t h e r e qu i r eme n ts given in t h is
perfo r ma nce c h eck , t he cali b ration procedure sh oul d be
p erformed . T h is proce dure ca n also be used by an
i n comi n g i nspectio
n
facility to determi
n
e acce
p tability
of
p e r forma
n ce .
REV . Α JUN 197 7
PERF O RM A N C E C HE C K
T h e electrical c h aracteristics are valid only if t he
SG 502 is cali b rate d at an am b ie n t tem pe r ature of +20° C
to +30 0 C and op erate d at an ambient tem p eratu r e of 0° C
to +50°C . F orce d air circ u latio n
is
requ
ired for
am b
ie
n t
tem p erat u res above +40°C .
Toleran ces t h at are specified i n t h is p e r fo r ma n ce ch ec k
proced u re apply to t h e i n st ru me n t un der test a
nd
do
n
ot
include test e q uipme n t erro r .
C h aracte r istics
P erforma n ce R equi r ements Su ppleme
n tal I n fo r matio n
Si ne W ave
Fr e q ue n cy R an ge
5 Hz to 500 kH z
Calibratio
n Accuracy W it h in 5 ο / ο of dial setti n g
f r
om
5Hz
to less t
h
a
n
50
kH z ; wit h i n 10 ο/ο
of d ial setti n g from 50 kH z to
500 kH z
Am p litude R esponse
W it h in 0 .3 dB over en tire r an ge
(1 kH z refe r e n ce)
M axim u m Out p ut
V oltage 5 V r ms, o pen circ u it, 2 .5 V rms
into α 600 Ω loa d
H a r mo n ic Distortio nL
ess t h an 0 .035% from 20 Hz to
50 kH z . L ess t h a n 0 .15% ove r t he
remaining fre q uency ra n ge
Hum/ N oise
L ess t han 0 .1 ο / ο of rate d ou
tput
Atte n tuatio n0
to greater t han 40 d B
conti n
uo
u sly
varia b le . 10, 20, a nd 40 d
B ste ps
wit h in
t2°/
ο
for eac h ste p
Sq uare W ave
F re quen cy R an ge 5 H z to 500
kH
z
Am p litu de
Approximately +5 V op en-circ u it
(+2 .5 V i n to α 600 Ω load)
R
ise
a ndF all Time L ess t h a n 50 n s i n to 50
Ω
o
r 600 Ω ;
te r mi n ated an d
meas u red at t he fro n t p anel
Sy n c I np ut
In p ut Im p eda nce 10 k
Ω

S p ecificatio ns and P erformance C h ec
k
-SG
502
Test
Eq ui p ment R equi r e d
The following test eq uip
m e n t, ore q uivalen t, is re qu
ire d
to perform t he
performance ch ec k , Test eq u i p
me n t
c h aracteristics
liste d are t h eminimum re q
uire d to verify
t he
performance of t h e eq ui p me n t u n d er
test . Su b stitute
e quipme
n t mustmeet or exceed t he state
d re qu i r eme n ts .
All test e qu i p me n t is ass
u med to be operating
wit h i n
tolera nce .
' R
equ
i
r es TM 500 se r ies p owe r
mo
d
ule
.
2-2
Ta b le 2-2
L ist of Test Eq
uipme n t R eq u irements
S p ecial test devices are used
w h ere necessary to
facilitate t h e p rocedure .
M ost of t h ese are availa b le from
Te k tro n ix, Inc .
a nd ca n be o rd ere d t hroug h your local
Te k
t r onix F ield Office or represen tative .
REV 13, JUN 197 8
P erfo rm ance
Desc
r i p tio
nR
equi r
ements A p plication
E xample
Oscilloscope
B a ndwi d t h , do to 50 MHz ; min
- Used t hr o ugh out
proce- α . Te k tro n ix 5440,
im u m d eflectio n facto r , 5
m V /div ; du re to pr
ovi de dis p lay . 5 Α 45, 5A1 3N, 51342
sweep rate, to at least
50 n s/div ;
Oscilloscope System .
differe n tial com p arator
ampli-
fier, compariso n
voltage,
0 V to±10
V .
Cou n ter M aximum F re q ue
n
cy,
500 kH z ; U sed for ste p
1 . α . Te k tronix DC
503 .'
P erio d
Avg mo d e ca p able to
10 3 ; O u tp u t sen sitivity,
5 V ; Display acc ur acy,
1 cou n t
i n 10 3 .
Distortio n
M easure h armo n ic d istortio
n , less U sed fo r ste ps 3, 4, and 6 .
α . H ewlett- P ack ar d
A n alyzer
t han .035% fro m 20 H z to 50
kH z ;
ΗΡ 334 Α .
less t h a n 0 .15%
over t h e r emai n i n g
fre q uen cy
r ange .
P owe r M od ule
Acce p ts TM 500-series p
l
u g-i
n s . P rovi d es p ower fo
r SG 502 α . Te k t r o n ix TM 503
.
a nd DC 503 .
10 Χ p assive Compati b le wit h test oscillosco p eU sed for ste p s 7 an d 8 . α . Te k tro n ix Ρ 6060 p r o be
.
pro be to be used
Termi n ation Im pedance, 50
Ω ; connectors, O
u tput termi n atio n fo r α .
Te k tro n ix P art No .
BN C ;
accu r acy, 2 ο/ο
sig n al ge n e r ators, if
011-0049-01 .
amplifier is n ot
50 Ω in p ut
im p
edance .
Terminatio nI
m
peda
n ce, 6000 ; conn ecto r s,
O u tput te r min ation fo r
α . Te k tro n ix P art No .
BN C .
sig n al ge n erators,
if 011-0092-00 .
am p lifier is
not 600 Ω i n put
im p edance
.
Ada p te r Connecto
r
s,
b a n an a plug to
H armonic distortio n and
α . Te k t r onix P art No .
BN C .
si n e-wave o u t p ut c
h ec k . 103-0090-00 .
Cable
Impe d a n ce, 50 Ω ; ty peR G-58
U ; U se d for sig n al
α . Te k t r o
n ix P art
No .
le n gt h , 42 i nch es ; con
n ectors, BN C . connectio
n t h ro ugh -
012-0057-01 .
out proced
u re .

P relimina r y P roce d ure
1 .

En su re t h at t h e correct n omi n al li ne selector b loc k
h as been i n stalled on t h e li ne selector
p i ns
on
t he P ower
M
od ule
i
n terface
board and t he regu lati ng rnage selecte d
i n cl ud
es
t h e applied li ne voltage . R efer to t he installatio n
section of t h e P ower M o d ule ma n ual .
2 .

En sure t h at all test e qu i p ment is suitably a d apte d to
t he a pp lie d line voltage .
3 . I n stall t he SG 502
i n
to
t h e P ower M o du le, an d if
a pp licable, install t he TM 500 series test eq uipment i n to
t he test e q ui p me n t P ower M odule .
4 .
Co
nnect t h e eq ui p ment un de r test and t h e test
e qu i p me n t
to
α suitable li ne voltage source . T urn all
equi p me n t on a nd allow at least 20 minutes fo
r t he
eq uipme n t to stabilize .
I n itial Co n t r ol Setti n gs
Set t h e following con trols du ri n g warm-up . time :
Oscillosco pe
I n te n sity, F ocus

Set for well-defi ned trace
an d normal brig
htness .
Differential Com p arator
V olts/Div

1 V
V aria b le

fully
clock
wise
(cal)
+ I
npu
t

DC
- I np ut

G N D
B a ndwid t h L imit

p us hb utton in
( Fu
ll ban
dwi d t h )
Seco nds/Div
M ai n V a r iable
Trigge
r i n g
+
Slo p
e
Auto Trig
AC Co u pl
Source
P ositio
n
Sw p M ag
C
HΑ
C H Β
L evel
Sp ecifications a nd P erfo
rmance C heck -SG 502
Attenuatio n
Cou p li n g
+ Slope
F un ctio n
Ν /Cloc k
R ate switch
H
old
Time B ase Plug-in
Co
u nte r
SG 502
1
ms
fully cloc kwise (cal)
selecte d
selected
selecte d
L
eft
Set so trace starts at
left side of gratic
u le .
n o r mal sweep
( n ot used)
E xternal source an d mid-
r ange
Χ 1
d o
selecte d
P
e
r
io
dΒ
10'-1 ms
fully cou n te r cloc kwise
(minimu m)
V A R A MPL IT U DE

fully clockwise
MUL TI PL I ER switc h

Χ 100 Κ ( pushbu tto
n i n)
STEP ΑΤΤΕΝ

all pus hbuttons o
u t
FRE Q UEN CY H z dial

any
positio n

S p
ecificatio n s a ndP erfo r ma n ce C h eck -SG
502
PERF O RM A N C E C
HE
C
K PR
OC
E
D URE
1 . C h ec k Dial Accuracy ; dial accuracy is wit h i n 5%,
5 Hz to less t han 50 kH z ; wit h i n 10%, 50 kHz to
500 kHz .
α . Co nn ect α50
Ω
ca b le
to t h e SG 502 Square-wave
ou t pu t con
necto r .
b . Co nn ect α 600 Ω termin ation to t he ot
h
er end of
t h
e
ca b le .
c . Connect t
he 600 Ω terminatio n to t h e Cou n ter CH Β
i n p u t conn ecto
r .
d . C HE C K -Dial settings a nd display u si n g t h e follow-
i n g ch art .
e
.
Disconnect t he 600
Ω termin atio n from t h e Cou n ter
and connect it to t he SG 502 si n e-wave out p ut conn ecto r .
f . Disco n nect t he 50
Ω
cable
from t he SG 502 s qu are-
wave
o
u tput conn ector, and conn ect it to t h eV e r tical
Am p lifier + I np ut .
2 . C h ec k Si n e-waveAmplitude ; response is
wit h in
.3 dB over en tire r ange (1
kH z refe r e n ce) .
α . Set time-base Time/Div switc h to .5 μ s .
b . Set t he time- b ase triggeri n g co n trols
for
an
υη -
triggere d conditio n .
c . A dj ust SG 502
V A R A MPL IT UD E co n t r ol for α6
d ivisio n display on t he oscillosco pe .
2-4
d . U se t h e followi n g ch art to ch ec k t h e si
n
e-wave
response .
e . Disco nnect
t he 50 Ω ca b le from t he V e r tical
Am p lifier
+
In pu
t conn ector .
3 . C h ec
k
Sine-wave Out
pu t V oltage ; 2 .5 V rms, i n to
600 Ω , ±0 .15
V .
α . Pr eset t h e followi n g front-pa n el co n trol setti
n g :
Distortio n A n alyzer
Fun ction

V oltmeter
M eter Ra n ge

3 volts
I npu t

N orm
SG 502
V ar Amplitude

F ully c ω
b . Co nn ect α Banana-to-
BN C a dap ter to t he Distortio
n
A n alyzer I n p ut .
ε . Connect t he 50
Ω
cab
le from t h e 600 O termination
on t he SG 502,
to t h e a d apter .
d . C
HE CK - M eter reads betwee n 2 .45 a n d
2
.65
volts
on t
he 0 to 3 volt scale .
e . Disco nn ect t he ca
b le from t he ad ap ate r , an d con-
nect it to t he + I npu t of t he
V e r tical Am p lifier .
REV . Α JUN 1977
SG
502
MUL TI P LI ER
Switc h
SG 502
FRE Q UEN CY
H z
d
ial
Oscilloscope
display
Am p litude
L imits
Χ 10 .5 5 .79 to 6 .21 div
Χ 100 .5
Χ 1 Κ .5
Χ 10 Κ .5 "
Χ 100 Κ .5 "
Χ 100 Κ 1 "
Χ 10 Κ 1 "
Χ 1 Κ 1
Χ 100
1
Χ 10 1 "
Χ
10 5 "
Χ
100
5
X1 K
5
Χ 10 Κ 5 "
Χ
100 Κ 5 "
SG 502
MUL TI PL I ER
SG
502
FRE Q UEN CY
Hz d ial
Co un te r
R AT E
Switc h
Cou
n ter
R eadi ng
Χ 100 Κ 5
10' 1 .80-2 .20 μ s
Χ
10
Κ 5 10 3 18 .0-22 .0 μ s
Χ 1 Κ 5 10 3 190-210 μ s
Χ 100 5 1 1 .90-2
.10 ms
Χ 10 5
1 19 .0-21 .0 ms
Χ 10 .5
1 190-210ms
Χ
100 .5
1 19 .0-21 .0 ms
Χ
1
Κ .5 1 1 .90-2 .10 ms
Χ 10 Κ .5 10 3 190-210
μ s
Χ 100 Κ - .5 10'
18 .0-22 .0 μ s
Χ 100 Κ 1
10' 9 .00-11 .0 μ s
Χ
10
Κ 1 10 3 95 .0-105 μ s
Χ 1 Κ 1 1 .095-1 .05 ms
Χ 100 1 1 9 .50-10
.5 ms
Χ 10 1
1
95 .0
-105ms

4 . C h ec k Attenuation ; 10, 20, a n d 40 dB ste p s
wit h in f2% ο for eac h step .
α . Set SG 502 FRE Q UEN CY d ial to 1 .
b . Set SG 502 MUL TI PL I ER switc
h
to
Χ l Κ (push but-
to n i n) .
c . Ad j ust SG 502 V A R A MPL IT UD E control for α5
divisio n display on test oscillosco pe .
d
.
Set SG 502 STEP
ΑΤΤΕΝ switch to 10 ( push butto n
ίη ) .
e . Set 5 Α 13 ΝV olts/Div switc h to 0 .5 V /Div .
f . C HE C K -Dis p lay on test oscillosco p e is between
3 .1 an d 3 .3 d ivisio ns i n am p litude .
g . Set SG 502 STEP ΑΤΤΕΝ switch to 20 ( p us h butto n
ίη ) .
h . P ush an d release SG 502
ST EP ΑΤΤΕΝ 10 switc h
( p ushbutton o ut) .
i . Set 5 Α 13 ΝV olts/Div
switc h
to
0 .1 V .
j . C HE C K -Dis p lay on test oscillosco pe is between 4 .9
an d 5 .1 d ivisions in am p litu d e .
k . Set
SG
502 STEP ΑΤΤΕΝ switc h to 40 (pus h butto n
ίη )
.
Ι. Pu sh a nd release SG 502 ST EP ΑΤΤΕΝ 20 switc h
(p us hb utto n out) .
η . C HE C K -Displayon test
oscilloscope is betwee n
4 .9 an d 5 .1 divisio ns in am
p lit ud e .
q . Ad j ust

SG 502

V AR

A MPL IT U D E slowly
cou n tercloc kwise and o
b serve display on test os-
cillosco pe for
α smoot h d ecrease i n am p litude .
m . Set 5 Α 13 ΝV olts/Div switc h to 10 mV
.
ο . Set 5
Α
13
Ν V olts/Div switc h to 1 V .
ρ . Pu sh a nd release SG 502 ST
EP ΑΤΤΕΝ 40 switc h
(pushbutton
out) .
r . Set SG 502 V A R A MPL IT U D E fully cloc
kwise .
Specifications a nd P erforma nce C h ec k -SG 502
5 . C h ec k H um/ N oise ; is less
t h
a
n 0 .1 ο / ο of rate d
output .
α . A dj ust SG 502 VAR A MPL IT UD E fo
r α 6- d ivisio n
dis p lay on t he test oscillosco pe .
b . Set SG 502 FRE Q UEN CY dial
to5a nd MULTIPLIER
switc h to Χ 10 ( pus h butto
n i n) .
c . Set t he time-base sweep rate to 20 ms .
d . Set t h e 5
Α 13 Ν - Input to V c (pushbu tton in), a nd t he
V olts/Div
switch to 5 mV .
e . Ad j ust t h e 5 Α 13 Ν Compariso
n V oltage F i ne co n trol
to p ositio n t he to p of t he trace to t he cen
ter of t h e graticule
area .
f . C HE C K - H um/ N oise is less t ha n
1 .2 division .
g . Set t he time-base sweep
rate to 10 ms .
h . Set t he SG 502 MUL TI PL I ER switc h to
Χ 100
(p ush butto n in) .
i . C HE C K - H um/ N oise is less t han
1 .2 d ivisio n .
j . Set SG
502 MUL TI PL I ER switc h to Χ 1 Κ (pus hb utto
n
in) .
k . C HE C K - H um/ N oise is
less t han 1 .2 d ivision .
Ι. Set SG 502
MUL TI PL I ER switc h to Χ 10 Κ ( push but-
to
n in) .
m . Set t he time-base swee p r ate to 5
ms .
η . Set t he 5 Α 13 Ν Compariso n V oltage F i ne cont
r
ol
so
t h e V olts dis p lay rea ds 3 .00, t
hen a dj ust t he control
countercloc k wise to p
osition t he top of t h e trace to t h e
ce n ter of graticule a
r
ea .
ο . C
HE C K - H um/ N oise is less t han 1 .2 d
ivision .
ρ . Set

SG 502

MUL TI PL I ER

switc h to

Χ 100 Κ
(pushbutton
i n) .
q . C HE C K - H um/ N oise is less
t han 1 .2 d ivisio n .
r . R emove
t h
e 50
Ω cable from t he 5 Α 13 Ν + In pu t .
s . Set t h e 5 Α 13
Ν- Input to G ND .

Sp ecificatio
ns an
d
P erfo r mance C heck -SG
502
6 . C h ec
k
H armo
n ic Distortio n ; is less
t h an 0 .035%
from 20
Hz to 50 kH z ; less t ha
n 0 .15% over t he
remai n i n g frequency
range .
ΗΡ 334 Α Distortio
n Analyze r
L i n e

ON
I nput

N o r m
Function

Set L evel
Se
n sitivity

M i n
V er n ie r
mi d ra n ge
M o d e

A u tomatic
F re qu ency

5 H z
Fr e que n cy
R
a
n ge

1 Hz
B ala nce
Coarse an dF i n e

midrange
H ig
h P
ass F
ilter

O U T
M eter Ra n ge

Set L
evel
b . Co nnect α Banana p lug
to BN C a d ap ter to t he
A n alyzer I NPU T .
ε . Co
nn ect α 600 Ω termi n atio n to t
h e Banana p lug to
BN C
ad a p te r .
d . Co nn ect α50 Ω cable
from t he SG 502 si n e-wave
o u t p ut conn ector to
t he 600 Ω te r minatio n .
e . Set t h e A n alyzer Se
n sitivity an d V er n ier for α meter
r ead i n g of 1 on t he 0 to
1 scale .
f . Set A n alyzer F
unctio n control to Distortio n .
g . A dju
st
A nalyze r F reque ncy d
ial
an
d B ala nce con-
trols for minim u m rea d i n g on t h e
meter .
h . Set t h e A n
alyzer M ete r R a n geco n trol to .3 on
t he
percentage
scale .
i . C HE CK -A n alyzer
meter reads less t h an 1 .5 on t h e 0
to 3 scale .
j . Set A
n alyzer M eter R a n ge a nd t he F un
ction controls
to
Set L evel .
k . Set

SG 502

F
re q
ue ncy d ial to 2, and
t he
MUL TI PL I ER switc h to Χ 100 .
Ι.
Set
Analyze r F re qu ency d ial to ap
proximately 20 ; set
A
n alyzer F re quency R ange
control to Χ 10 (fre q uency
200 Hz) .
2-6
m . Set
A n alyzer V
e
rn ier
co
n trol for α meter rea d i n g of
1
on
t he 0 to 1 scale .
η . Set A n alyzer Fun ction co n trol to Distortio n .
r . Set A n alyzer M eter R ange an d
Fu nctio n co n trols to
Set L evel .
s .
Set SG 502 FRE Q UEN CY d ial to 5, a nd t he
MUL TI PL I ER switc h to X1 K .
t . Set Analyzer
F re q ue ncy dial to ap p roximately 50 .
υ . Set A n alyzer Fr eq u ency R an ge co
n t r
ol to
Χ 100,
(fre q ue ncy 5 kHz) .
ν . R
e p eat
p arts m, η , ο , and ρ of t h is ste p .
ω . C HE C K -Analyzer meter rea d s
less t h a n .035 on
t h e 0 to .1 scale .
χ . Set Analyzer M ete
r R ange a nd F un ctio n co n
trols to
Set L evel ; set A n
alyze r F re q ue n cy R an geco n t r ol to X1 K
(freque n cy 50 kHz) .
γ .
Set
SG
502 MUL TI PL I ER
switch to Χ 10 Κ .
τ . R e p eat pa r ts
m, η , ο , a nd ρ of t h is step .
αα . C HE CK
-Analyzer mete r reads less t ha
n .035 on
t h e0 to .1 scale .
ab . Set A n alyzer
M eter R ange and F unctio n co n trols
to Set L evel .
ac . Set SG 502 MUL
TI PL I ER switch to Χ 100 Κ .
ad .
Set A n alyze r F re qu en cy R an ge co
n trol to Χ 10 Κ ,
(fre quen cy
500 kHz) .
ae . R epeat parts
m, η , an dο of t h is ste p .
af . Set
Analyzer M ete r R a nge control to .3 on
t he
p ercentage scale
.
ag . C HE C K -A n alyzer
meter reads less t h a n 1 .5 on t he
0 to 3 scale .
ah . R emove t h e 600
Ω termination and 50
Ω
ca
b le
from t h e SG
502 and t h e A nalyze r .
REV Α , JUN 1978
α .
P reset t h e followi n g
SG
502
fr o n
t- p a n el co n trols settings :
Oscillator
ο . A dj ust A n alyzer F re qu ency d ial a nd B ala nce co n -
trols for m i n imum r eadi n g on t h e meter .
VAR
A MPL IT U D E f u lly cloc kwise ρ
.
Set
A nalyze r M eter R an ge co n trol to .1 on t he
MUL TI PL I ER switc hΧ
10 (push b utto ι i,? η ) p e
r
centage
scale .
STEP ΑΤΤΕΝ
pus hb utto ns out
FRE Q
UEN CY Hz d ial .5
q . C
HE
C
K -A n alyze r meter rea d s less than .035
on the
0 to .1 scale
.

7 . C h ec k Squa r e-wave am p litude ; 2 .5 V into 600
Ω ,

8 . C h ec k S q uare-wave rise a nd
fall
time ; 50 ns or
wit h i n 250 m V .

less .
α .
Pr eset t h e followi ng fro n t- p a n el con t r ol setti n gs :

α . L eave con trols of test e q
uipme n t
a
nd ca b le
co
nn ec-
tio
n
s as d escribed
i n ste p 7α t h roug h e .
Oscillosco p e
I n te n sity, F ocus

Set for well- d efi ne d tr ace
a ndn ormal b r ig h t n ess .
Diffe r en t i al Compa
r
ator Plug-in
V olts/Div

50 m V
V a r ia b le

fully cloc k wise (cal)
b . Co nn ect α600
Ω termi n atio n to t he SG 502 s q uare-
wave ou t p ut conn
ector .
ε . Co nn ect α 10
Χ p r
o
b e to t he 5Α13 Ν +I n p u t co n nec-
to r .
d . Co nn ect
t he p r obe gro und clip to t
he ou te r portio n
of t h e
600 Ω termi n ation .
e . Co nn ect t h e pr obe
ti p to t he in n e r co nn ector of t
h
e
600 Ω te r mi n atio n .
f .
C
HE C K -Dis p lay on test oscillosco p
e is b etwee n
4 .5 a nd 5 .5
d ivisio n i n amplit ude .
REV Β , JUN 1978
S p ecificatio n s a n d P erfo
r
ma
n
ce C h eck -SG 502
b . Set 5 Α 45 V olts/Div switc
h to 20 m V .
ε . Ad ju st t he 5 Α 45 V a r iable con t r ol fo
r α 6- d ivisio n
d is p lay .
d .
Set time-base Time/Div switc h to
50 ns .
e . C HE C K - W aveform rises from its 10% to 90°/ ο p oi n t
2- 7
+ I n put
- I npu t
Time
DC
G
N
D
B ase Plug-in
wit h i n50 ns (1 divisio n ) .
f . A dj ust t h e time-base L evel/Slope con trol to its
n egative slope regio n .
Ti m e/Div 1 ms
g . C HE C K - W aveform falls from its 90 ο /οto 10% p oi n t
V aria b le
f u lly cloc k wise (cal)
wit h i n 50 ns (1 d ivisio n ) .
T r igge r i ng
L
evel/Slo p
ep ositive slo p e region
h . R emove all co nn ectio n s f r om t h e SG 502 a
nd
5
Α 45 .
M
o
d e A U TO T R IG
Co up li n g AC
So ur ce I n te rn al
Th is com p letes t h e p erfo r ma nce c h eck of t he SG 502 .
P ositio n Set so
t r ace starts at left
si de of gratic u le .
Sw
p M ag o u t
SG 502
FR E Q UEN CY H z dial 5
MUL TI PL I ER Switc
hΧ 100 Κ ( p us hb utto n i n)

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

Int r oductio n
T h is a dj ustme n t p roce dur e is to be u se d to r estore t he
SG 502 to its o r iginal p erforma n ce specificatio n . A dju st-
m en t n eed n ot b e p erfo rm ed un less
t he i n st r u m e n t fails to
meet t
h
e re q ui
r eme n ts liste d in t he Specificatio n sectio n ,
o r t h e
P
erfo
r
ma
nce C heck cann
ot
b e com p leted satisfac-
torily .
Com p
letio
n of all ad j
ustme n t ste p s i n t h is pr ocedu r e
en su res t h at t he
i
n strume
n
t
will meet t h e p e r forma n ce
r eq ui r eme n ts liste d in t h e Specificatio n sectio n . H owever,
to f u lly ensu r e satisfactory performa n ce, it is recommend-
ed t h at t he P e r forma n ce C h ec k be performe
d afte r
any
ad j
ustme n t is m ad e .
Services Available
Te k t r o n ix, I n c . p rovi d es co mp lete inst ru me n t r epai r
a n d a dj ustme n t at local F iel d Service Ce n ters an d at t he
F actory Service Ce n ter . Co n tact your local Te k tr o n ix F iel d
Office o r re pr ese n tative fo r f u rt he r i n for
m
atio
n .
Test Equ
i p me n t R eq u i r ed
T he followi ng test e quipme n t is r e qu i r ed to p erfo r m t he
A dj ustme n t P roced u re . Α d o voltmete r wit h t h e followi n g
s p ecificatio ns is r eq ui r e d fo r c hecking t h ed o p ower
s upp lies : R an ge : ±20 volts ; Accuracy :
1%
or b
ette r ;
R ecomme nd ed e q uipment : Te k tr o n ix D M 501 Digital
Mu ltimete r .
Α flexible p l u g-in exte nd er, Te k tro n ix
P
art No . 067-
0645-01, is u sef u l fo r tro ub les h ooti n g o r a dju sti n g t he
SG 502 ; h oweve r , t he com p lete A dj ustme n t Pr oce du r e
can be p erfo r me d wit h o u t u se of t he exte nd e
r .
Α TM 500-se r ies P owe r M o d ule is r e qu i r ed fo r
troubles h ooti ng o r a dj usti ng t he SG 502 .
R
ecomme
nde d
e qu i pm e n t : Te k t r on ix TM 503 .
P
re p
aratio n
Sectio n 3-SG 502
AD JU ST MEN
T
α .
R emove t h e left si d e cove r of t h e SG
502
to
gai n
access to t he com p o ne n t si de of t he ci
r c u it boa r d . Pull the
r ear e nd of t he si de cove
r outwar d f r om t h e side of t he
i n st r ume n t (t
he
cove
r s na ps i n to p lace) .
b . If t he SG 502 is to be ad j uste
d wit h o u t use of t he
flexible p lug-i n exten d e
r , r emove t h e P owe r M od u le
ca b i n et cove r .
ε .I n stall t
h
e SG
502 i n to t he left P owe
r M
o
du le
com
p artme n t, or if app r o pr iate, conn
ect t h e SG 502 to t he
Power M od u le b y mea ns of
t he flexi b le pl u g-i n exte nder .
d . Set t h e
P ower M o du le for t h e li n e voltage to
b e
ap p lie d (see
P ower M od ule ma nu al) an d con
n ect it to t he
li n e
voltage so ur ce . Be sure t h at t he p
ower switc h is off .
e . I n stall all TM 500-se r ies eq
u i pm ent, i n cludi n g t he
SG 502 i n to t he P ower
M odule .
f .
Co
nn ect all test eq ui p ment to α
suita b le li ne voltage
so
urce .
g . T u r n on all test e qu i p
ment a n d allow at least twe n ty
mi nu tes for t h e e qu
i pm e n t to warm up a nd sta b
ilize .
I n itial Control Settings
Set t h e followi ng co n trols
duri ng warm-up time :
SG 502 Oscillato r
VA R A MPL IT UD E

f u lly cloc
kwise
MUL TI PL I ER switch

Χ 100 Κ (push butto n in)
STEP ΑΤΤΕΝ

all push butto ns ou t
FRE Q UEN
CY Hz d ial

any p ositio n

Ad j
ustment-SG 502
1 . C h ec k P ower Su p ply V
oltages
α . Co nnect
t h e digital voltmeter between
+20 V test
poi
n t on t he circuit b oard, an dch assis
grou n d . See Fig . 3-
1 fo r voltage test poi
n t locatio n .
b . C HE C K -
For α meter reading of
+21 .0 to
+19 .0 volts .
c . R
epeat p art α of t h is
step for t h e -20 volt su p
ply .
d . C HE C
K - For α meter
reading of -21 .0 to
-19 .0 volts .
3- 2
e . Disconnect
t h e d igital voltmeter .
2 .
Ad j ust AGC
V oltage
α . Co n nect t he
d igital voltmeter between t h e
AGC test
p oi n t on t he
circuit board, and ch assis
groun d . See Fig . 3-
1 for
test poi n t location .
b .
Set t he Oscillato r FRE Q
UEN CY Hz d ial to 5, t h e
VA RA
MPL IT UD E control fully cloc
k wise, an d p ress in t he
Χ 100 Κ
MUL TI PL I ER pus hbutton
. All STEP ΑΤΤΕΝ
p us h
button s must be out .
c . AD JU ST-AGC
Ad j ust, R 115, for α
meter readi n g of
-2 .5 volts .
See F ig . 3-1 for ad j ustme n t
location .
d . Disco n nect t he d igital
voltmeter .
+20 V
Test
3 . Ad j
ust Output V oltage
F ig . 3-1 . L ocation of test
p oi n ts, AGC a nd
Gain ad ju stmen ts .
α .
Co nn ect an ac voltmeter
betwee n
t h e si n ewave
outp ut BN C
connector on t he
front p anel a nd ch assis
grou n d .
b . Turn t he V
A R A MPL IT U DE co
n trol fully cloc kwise
and c heck t h at all
ST EP ΑΤΤΕΝ p
us h butto ns a r e out .
c . Set t he FRE Q UEN CY
Hz dial and t he MUL TI PL
I ER
pushbuttons for α 1 kH
z sig n al .
d . AD JU
ST-Gain Ad j ust, R 191, for
α meter r ea d i ng of
5 volts,
rms . See F ig . 3-1 for ad j
ustme n t locatio n .
e . Connect
α 600 Ω terminatio n to
t h e BN C sinewave
output
connector .
f . Con nect an
ac voltmete r betwee n t he 600
Ω termina-
tion an d ch assis grou
nd .
h . Disco n nect t he voltmeter an d
remove t he 600
Ω
termi n atio n .
T h
is
com p letes t he Ad j
ustme n t proce d ure of t
h
e
SG 502 Oscillator .
g . C HE C
K - F or α meter readi ng of
2 .5 volts, rms .
R 191
Gai n
A dju st

P reve n tive M aintenance
T here are no special p reve
n
tive
mai n tenance
p rocedures t h at apply to t he SG 502 . R efer to t he P ower
M od u le i n struction ma nu al fo r ge n eral p reventive
maintena n ce proce d ures and instr u ctio ns .
Corrective M ai n tenance
R efer to t he P ower M
o du
le i n st
ru ctio
n
ma
n
ual
for
ge n e r al corrective mai n te n an ce proced u r es a nd i n struc-
tio ns .
T r ou
b
les
h
ooti
ng
U se t he P erforma nce C h ec k , Ad ju stment P roce d ure,
a nd Circuit Descri p tion as ai d s to locate trouble i n t he
eve n t of e quipme n t failu r e .
T
he test e qu
ip m ent listed i n t he
Pe r fo r ma nce C heck and A dj ustme n t P roced u res will
p rove useful i n trou b les h ooti n g t h e SG 502 .
M AI N T EN A N C
E A N D
I NT ERF ACI N G
I NF
O
RM ATION
F u n ctions Available at R ea r Co nn ector
Con tact
28 Α
27 Α
26 Α
25Β
25 Α
24 Β
Assign m e n t
Si ne
W
ave O u t
Sine
W ave O u t G ro un d
Sy n cOut G r o un d
Sync
i n ( N ot F actory W i r ed )
Sy n c O u t (S qu a
r
ewave o u t Β070750 & b elow)
Sync
Gro und
(
N ot F actory W i r e d )
1430-06
F ig . 4- 1 . I npu t/O u t pu t assig nm e n ts at r ea
r conn ecto r .
Sectio n 4-SG 502
Α slot b etwee n p i ns 23 a nd 24on t
he rear con nector
ide n tifies t he SG 502 as α
member of t he sig n al so ur ce
fa m ily . I n sert α barrie r i n t h e correspo n di ng p osition of t h e
P ower M o du le j ack to p r eve n t ot h er t h a n sig n al sou r ce
pl u g-i ns from bei n g use d i n t h at com p artment . T h is
protects t he p lug-in sh ou l d specialize d connectio
ns b e
ma d e to t h at com p artment . Co n sult t he B
uildi n g A System
section of t h e
P
owe
r M
o
d ule ma n ual for furt h e r i n forma-
tio n .
Signal o u tputs, or ot h er specialized con n ectio n s, are
made to t h e rear i n terface co nn ectors as sh ow n i nF ig . 4-1
.
T he Sy nc In a nd Sync Groun d are n ot factory
wired . T he
Sy n c Out sig n al is α si n e wave of t h e same
f r
eq u
ency as
t h e outp u t sig n al . It h as an am p litude of
at least 1 V r ms,
w h ic h is esse
n tially co n sta n t over t h ee n tire f r eque n cy
ra n ge . T h e sou r ceim p eda n ce is 1 k Ω . U se t h is signal to
trigge r exte rn al devices suc h as oscilloscopes or coun
ters
etc .

Intro
du ctio n
T h is sectio n of t he m a n ual co n tai n s α d esc r i p tio n of t he
circuitry u sed i n t he SG 502 Oscillator i n divi du al d escrip-
tions a r e sep a r ate d i n to t he followi ng parts : Sy nc I npu t,
Oscillator Amplifier, AutomaticGai n Co n trol, F re q ue n cy
Co n t r
ol,
B uffer Am p life r , Atte nu ato r , S qu a r e- W ave O u t-
pu t, a nd P
ower Supply
. R
efer to t h e ap p ro p riate diag
r
ams
i n t h e Diagrams
sectio
n
of
t h
is manual
w h ile
readi
n g t h
e
circ u it d esc r iption .
Sync In p ut
T he Sy n c I npu t sig n al is a pp lied to t h e+si d e (Q10A) of
t he oscillato r am p lifie r t h ro ugh C10 and R 10 .
Oscillator Amplifier
D u al FE T's 010 Α a n d Q10 B pr ovi d e d iffe r ential
am p lificatio n , wit h Q70, R 71, R
73 an d
R
75
serving
as t
h
eir
co n sta n t cur r ent source . T h e FE T's drive diffe r ential
tra n sisto r s Q20 an d Q24, wit h Q30, R 32, R 35, an d R 36
servi ng as t h eir co n sta n t c ur re n t sou r ce . Q86 su pp lies
co n sta n t cu r r ent to emitte r -followe r Q80, w h ic h d r ives
o u t pu t emitte r -followers Q82 an d Q88 . P ositive feedbac k
fo r oscillatio n occ u rs t hr oug h R 117 a nd C12 .
Automatic
Gain Cont
r
ol (AGC)
Peak
d etecto r Q90 an d FE T Q110 com p ose an
automatic gain co n t r ol circuit . T he FE T ope r ates as α
va r iable resisto r in αd ivider co n figuration composed of
R 115 (AGC ad j ust m en t), R 116, a nd R 117 . T he divide r is
co nnecte d from t h e out p ut of t he oscillato r amplifier to
grou nd , a nd varies t h e amou n t of
p
ositive fee d bac k .
Voltage at t he gate of Q110 is p r oportio n al to t he pea k
si n e-wave am p litude . T he s hun t ca p acitors p r ovi d e
smoot h i ng at t he va r io us f r eq ue n cies .
Fr e q uency Co n t r ol
T he o u tp u t from Q82 a nd Q88 is fed bac k to t h e mi n us
i npu t (Q10
B ) of t
he
oscillator am p lifier as n egative
fee db ack t hr o u g h t h e b r idge d Τ n otc h filte r . M i n im u m
voltage t r a n sfer occ ur s at t he o u t p ut f r e q ue n cy . Ad ju sti n g
t h e ga n ged co n trols R 50A a nd R 50 B (la b eled FRE-
Q UEN CY Hz a nd located on t h e fro n t p anel) varies t h e
n otch
fr
e qu e n cy .
B uffer
Amplifier
Atte n uator
Sectio n 5-SG
502
CI R C U IT
D E
SC
R I P TIO N
T h e bu ffer am p lifier (Q120, Q128, a nd Q130) pr ovi des
isolatio n b etwee n t he oscillator am
p lifie r a nd t he outp ut
circuit r y . 0120 a nd Q128 fo
r m
α
diffe r
e
n tial
am
p lifier
su pp
lie
d by α consta
n t cur re n t
so
ur ce 0130, R 130, R 132,
a nd R 133 . T h e collector of Q120 d rives t h e b ase of Q140,
casco d ed wit h Q145 . T h e collector of Q145 dr ives Q150
and Q154 i n α commo n emitte r co n figu r atio n . C R 150 an d
CR 154 pr ovide pr op er biasi ng . N egative fee db ack occ urs
t hroug h C120 . Gain is set
b y Gai n A
dj
ust 191 .
F our Τ sectio n s, t hr ee fixed a nd one va r ia b le, com pr ise
t h e co nstant-imped a nce 600 Ω atte nu ator .
R 160 d ete r -
mi nes t h e in p ut im pe d ance .
Each section exce p t t h e
va r ia b le is switc hable i n or out to p r ovi d e atte n uation
ste ps .
Squa r e- W ave Output
T he out p ut si n e-wave from t he bu
ffe r
am
p lifier is fe d
t hr o u g h R 195 to diodes CR 195, C
R 196, C R 198, a nd
C R 199, w h ic
h limit t h e p ositive a nd n egative excu r sio n s .
Collecto
r
s of
0200 a nd Q210, α d iffe r en tial am p lifie r , are
furt h er cla
mp ed by diodes C R 200 a nd C R 202 . T h eout
pu t,
at 600 Ω , is ta ken fr om t h e collecto r of
Q220, w h ic h forms a
d iffe r en tial am p lifier wit h 0230 .
T
h
ei r co n sta n t cu r re n t
sou r ce is s upp lied by Q235,
R 235, R 238, an d R 240 .
P ositive feedbac
k from t h e collecto r of Q230 ensur es fast
switc h i n g . Dio d es
C R 210 an d C R 212 limit t h e voltage
excursions an d e ns ur e o p eratio n i n
t h
e non-saturated
mo d e .
P ower Sup p ly
I nteg r ate d ci r c
u
it U
320 provides t h e regulate d do
voltage s upp ly for t h e
ci r c u its . Co n ductio n of t h e se r ies-
pass t
r
an sistors
i n t he mai n frame is cont r olled b y
t h e
current t h roug h U 320 . Th is cu rr e n t dete r mines t
hevoltage
d r o p ac r oss R 320 an d R 340 . T h erefore, U
320 ca r ries only
part of t he necessary cu
rr e n t, with t he r emainde r b ei ng
s upp lied by
t he se r ies-pass tra n sisto r s . T he voltage d ro p
ac r oss
R
322
an d R 342 activates h ard cu r re n t-limiti ng i n
U 320
. R 348 determi n es t he out pu t voltage, w h ile C322 a nd
C342 p rovide
n egative
ac feed
bac k for smoot h ing .