Tektronix 2235 User Manual

Ope r ati ng Inst r uctio n s-2235 Service
Th e followi ng basic o pe r ati ng i n fo r mation a nd tec h n i q ues
sh ould be co n si d ere d before atte m p ting
to ma
k
e
any
mea-
surements wit h you r instr u me n t .
T h e gratic u le is internally mar ke d on t he face p
late of
t h
e
c r t to enable accu r ate measurements wit h out p a r allax e r ro r
(see Figu r e 2-8) . It is ma rk ed wit h eig h t vertical and te n h ori-
zon tal ma j o r divisions . E ac h ma j or division is d ivi d ed into
five subdivisions . T he vertical d eflection factors and horizon-
tal timing a r e calib r ated to the g r aticule so t h at accu r ate
measureme n ts can be ma de d irectly from t he crt . Also, per-
centage mar k ers for t h e meas urement of rise an d fall times
are locate d on t he left side of t he g r aticule .
T he most r eliable signal measurements a r e ma de w hen
t he 2235 and t he unit un d er test are connected by α com-
mon reference (gro und lea d ), in a dd ition to t h e signal lea d or
probe . T he prob e's gro und lead provides t he best g r oun di ng
met h od fo r sig n al i n te r connectio n a n d e n sures t he maxi-
m u m amount of signal-lea d sh iel d ing in t he probe ca b le . Α
separate gro u n d lea d can also b e connected from t he unit
under test to t he oscillosco p e G ND co nnecto r located on
t he front p an el .
Generally, probes offer t h e most convenient means of

Wh
e
n
t
h
e
i np
ut cou p li
ng
switc
h
is set to G N D, t he i np ut
connecting an inp u t signal to t h e instrument . T hey are

signal is connected to groun d t h ro u g h t he inp u t cou pling
sh iel ded to prevent p ic ku p of elect r o m agnetic i n terfe r e n ce,

capacitor
in
se
r
ies
wit h
α
1

ΜΩ resistor to form α
and t h e su pp lie d 10 Χ p robe offers α h igh i n put im p e d ance

prec h arging network . T h
is
n etwor k
allows
t h
e
i np
ut cou p li ng
t h at minimizes circ u it loa d ing . T h is allows t h e circ u it u nder

ca p acito r to c ha r ge to t h e av erage d c-voltage level of t he
test to o pe r ate wit h α minimum of c h ange fro m its no rm al

signal applied to t h e prob e . T hus any large voltage
con d itio n as meas u reme n ts a r e bei n g ma de .

transients t h at may accidentally be ge ne r ated will not be
app lie d to t h e am p lifie r i np ut w h e n t he i np u t coupling switc h
is move d from GND to AC . T he prec h arging network also
Coaxial cables may also be used to con n ect sig n als to

provi
d es α meas u re of protection to t h e external circ u itry by
t he i np ut con n ectors, but t hey may have co
n
si de r able effect

re d ucing t he cu rrent
levels
t h at can
be
dr awn fr
o
m t h
e ex
on t he accu racy of α d isplaye d waveform . To maintain t he

ternal ci r
cuit
r y
during cap acito
r
cha
r gi n g .
original freq uency ch aracteristics of an applie d signal, only
h ig h - q uality, low-loss coaxial ca b les s ho u l d be u sed . Coaxi-
al cables sh oul d be te
r min
ated at bot
h
e
n
ds in t
h
ei
r
c
h
a
r
ac-

T he following proce du re s h o u ld b e used w h enever t he
teristic imped ance . If t h is is not possi b le, use suita b le

pr obe ti p
is con
n
ecte
d
to α
sig n
al sou
r
ce having α
different
impe d ance-matc
h ing
d evices .

do
level
t h a n t h at p reviously app lie d , esp ecially if t h e d c-
G R ATIC ULE
G R O UN DI N G
O
PER ATI
N G CO NS I D ER ATIO NS
I ST OR LEFT

11TH O RR IG HT
VE R TICA L

VER TICA L
GR ATICU
LE

GR ATIC ULE
LINE

LIN
;E/
90

. . . .
. .
RISE AND

C
EN TER
F A LL TIME

C ENTE R

H O RIZO N TAL
M EASU REMEN
T
VERTICA L
G R ATIC ULE
PERCENTAGE

LI N E
M A RKER S
GR ATIC ULE
LINE
Figu r e 2-8 . G r aticule measu r
eme
n
t ma
rk ings
.
I NPU T CO UPL I N G
SIG N A L CONNE CTIO N S

CA
P ACITO R PRE
C
H A R
GI N G
4207-09

Tektronix 2235 Specifications

General

Brand	Tektronix
Model	2235
Category	Test Equipment
Language	English