Tektronix 7a11 Instruction Manual page 58

(Αί
(8)
Set the top of the display to graticuie ce n ter,
u si n g the 7 Α 11 POSITION co n trol . Th e n
s
w itch t h e 3S1
C h annel Α an d
C
h a n nel Β mV olts/Div co n trols to 5 mV .
Re-adjust t
h
e 7 ΑθΙ POSITION control to keep th e to
p
of
the displa y at gratic u ie ce n ter .
(9) CHECK-Display sh ould be similar to t h at observ-
ed in step 12-d (7) . Deviatio n
s
h
oul
d
be ap p roxi m ately
withi n 41 divisio n , wh ich is equal to !- 2% .
j ιυ l r τ eρe ατ τπ e τ
r
αη
in Table 5-6, striving to
(11) Remove the Exten d er (and attached 7A1 1) from
the plug-in compa r tm ent .
(12)
I
nstal l
t
h e 067-β 587-00 Calibration
F
ixture
(item 9) in the vertica l plug-in compartment . Sw itc
h
it
to 250 k H z, + Step Res p
onse, and adjust th e
A m p litu d e
to obtain α ce n tered 6-division
d
isp lay . Switc h the swee p
rate to .05 Ιι s/division and set t h e ste p fu n ction to occur
at t h e seco n d line fro m the left of th e graticule as in Fig .
5-13, Note t h e sh ape of the top-left cor n er of the pulse .
It ωίΙί be used as α refere n ce .
T h e existence of two vertical compartments in an
Oscilloscope permits the Calibration
F
ix ture to
b e
left in the Oscilloscope for continual trace reference
while chec k ingfadjusting t
h
e 7Α 11 . Ho wever, it must
first be determ ined that th e respo n se of the two co m -
partments is esse n tially iden tical.
η
/
V
OT E
ι
Sta
r
t of ste
p
function
set o
n
e division fro
m
!
left side of gratic
u
ie
Fig . 5-13 . Ste
p function position fo
r
t
r ansien t res
p
onse a
dju
st
m
ent,
step 12 .
P
erfor m a n ce Check/Calibration-7A 11
(13) I n stall t
h
e 7 A 1 1
d
irectly into t
h
e Oscillosco
p
e
vertical com p art m ent .
(14) Ad
j ust th e Ty p e 106 S q
uare Wave Generator +
Transition Amplitude to obtain α 6
d
ivision, 250 kH z
d
isp lay .
P
ositio n
t
h e displa y as in Fig . 5-13 . T h e step
fu n ction s
h
o u ld be esse n tially th e sa m e as t
h
at
p
rovi d ed
b
y the Calibratio n F ixture .
NO ΤΕ
The step function must appear in t h
e same area of t
h
e
C
R
T as t
h
e waveform against w
h
ic h
it is being com-
pared, if the 7Α 11 display is not essentiall y
t
h e sa me
as th e Calibration
F
ixture disp lay, re-ad
j
ust C255 a n d
R255 to ma
k
e it t
h
e same. However, if re-ad
j
ustm ent
is do n e, th e waveform must again be compa red
against the Sampling System referen ce waveform, as
in step 12-e (2), (5), (δ), (8) and (9) . W
h
en C245
and R245 a r e properly ad
j
usted, t
h
e step function
observed on th e Sampling System C R T will duplicate
the mean trace shape of th e refere n ce waveform
d
rawn on t
h
e Sampling Syste rιι CR T, and the step
function obser ved on the 7000-Series Oscilloscope
will duplicate t h e Calibratio
n
Fixture step functio
n
.
I n abil ity to meet t
h
is requirement indicates dϊssirni-
larity between t h e square waves p rovided b y the Type
106 and t
h
e Calib ratio n Fixtu re, a situation which
should not exist in properly calibrated test equip-
ment .
(15)
RE
-AD
J
U ST-C255 a nd 8255 (
F
ig . 5-12) as
necessary to ma k e t h e 7 A 1 1
d
is
p
lay as
n
early li k e t
h
e
Calibratio n F ixt u re disp lay as possible . Do not cha n ge
espo ι len t -'Re-
i n th
;.3amt .
; - 1 if
f, Switch t h e Time Base Triggering Source to
N
orm .
g . C h ec k
t
h e res p o n se of t
h
e Calibration
F
ixt u re at each
setting indicated in Ta
b
le 5-7 . T h ese will be used as refer-
ence wa vefor m s against w
h
ic h
t
h e 7 Α 11 res p o n se will be
c h ec
k
ed . The ar ea to
b
e observed is i n dicated in Fig . 5-14 .
N
ote any aberrations or deviatio n s from flatness.
h .
Select 250 Hz at th e Ty p e 106 Sq uare Wave Ge n -
erator and 1 ms at th e Time Base . Then ad
j
ust t
h
e Type
106 Squ are Wave Ge n erator + Transition A m plitu d e for
exactly 6
d
ivisions
d
is
p
la y
a
mp litu de . (7 Α 11 at 10 m V .)
Ad
j
ust t h e
7 A 1 1
P
OSITIO N co n trol to align th e center of
t he to p of th e waveform accuratel y with
t
h
e
h
orizo n tal li n e
1 division below t h e top of t h e graticuie, as in
F
ig . 5-14 .
Th is
h
orizontal line
w ill be referred to as the "horizontal
refere n ce li n e" for the re m ainder of t h is step .
5- 1 7