Tektronix 7a11 Instruction Manual page 53

Perfor m a n ce C
h
eck/Cali b ratio n -7 Α l 1
k .
Disconnect t h e
P
robe from t
h
e Store d
P
robe Input
Ada pter . Set th e 7 Α 11
V
O
L
TS/DI V to .1 V . Usi n g t
h
e
POSITION co n trol, center t
h
e trace .
θ . A d just th e ST E
P
ΑΤΤΕΝ BA
L
so that mi n im um trace
s
h ift acco mp a n ies sw itch i
n
g bet ween +UP a nd IN V ERT
P
olarity .
m . Select +U Ρ
P
olarit y .
η . C H EC K - V A
R
IA
BLE
balance . Trace s
h
ift accom-
panying rotatio n of VARIA
BL E control shoul d n ot excee d
0 .2
d i v isions .
ο .
S
w itch th e Time Base to A u to, AC, Internal Trigger-
ing .
ρ . Pus h in an d release t h e
V
A
R
IA
BL
E
k
nob,
p
laci n g it i n
its calibrated positio n .
q .
Set t
h
e 7A 11 VO
L
TS/DI V to 5 mV .
7 . C h ec k /A
dj
u st Offset
V
oltage (OFFSET OUT
CA
L
-
R
320)
5-12
REQUIR EME NT : O f fset ra n ge fro m --1 V (±10%) to 11
V (±10%) ; OF F SET O U T voltage s
h
o u ld be within 0 .5
mV +1% of of fset
v
oltage applied internall y to am p li f ie r
with VO
L TS/DIV switch in any of the 5 mV throug h 50
mV positio n s .
NO ΤΣ
Either th e Amplitu de Calibrator And Co m parator
(acc urate to within 0.25%) or the 7000-Series Oscillo-
scope Calibrator (acc urate to within 1%) can be used
in the following procedure . Accurac y will be approxi-
mately 1 % less reliable if the latter is used.
α . Control setti n gs given in Ta b le 5-2 apply, e x ce p t th at
th e
7 A 1 1 VOLTS/DI V co n trol is at 5 m V .
b .
U
si ng the 7 Α 11 POSITION co n t rol, set the trace
accurately to graticule center . Do not mov e th e POSITION
co n trol
f or th e rest of t h is step .
ε . Select +DC at the Amp lit ud e Calibrator And Com-
parator . T h e n set it for α .5 V o u tput ; or select DC at the
Oscillosco p e Calibrator and set it for α 0 .4 V DC o u tp ut .
d . Connect the
P
ro b e tip (via t
h
e Stored
P
robe Input
A d a p ter an d coaxial cable) to th e O u t
p
ut connecto r of the
A mp litu d e Cali
b rato r And Co m
p
arator or t
h
e 7000-Series
Oscillosco p e Calibrator .
e . At t h e 7A1 1, select Offset ON .
T
h en ad
j
u st t h e FINE
Offset control as
n
ecessary to acc u ratel y set t h e trace to
graticule ce n ter .
f.
C HE C
K
-OFFS ET
O
U T accuracy .
U
sing the Differ-
ential
V olt m eter and th e Cable Asse m bly (ite m 18), c h eck
the voltage at t h e OF F S E T O U T jack . It sho u ld be equal to
t
h e following : -500 m V ±5 .5 mV wit
h
Amplitude Cali-
brator And Co m parator ; -400 r
n
V -
+-10 .5 mV with Oscillo-
sco p e Calibrator .
g . (Calibration
P
roce d ure only .) AD
JU
ST-O
FF
S
E
T
JU T CAL - 8320 (
F
ig . 5-8) as
n ecessary to obtain 500 m
V
)
FF
S E T O
U
T voltage wit
h
Am p litu d e Cali
b
rator An d
'om p arator, or 400 m
V
wit
h
Oscillosco p e Cali
b
rator .
N
ote
t
h
at R320 interacts on t
h e trace position and t h e front-
ιαη e Ι O
FF
S
E
T controls will
h
ave to be rea d
j uste d to keep
h .
C H EC K -OFFS E T OUT range .
F
i rst rotate the O FF-
S E T controls f u lly counte rcloc kw ise and c h ec
k OFF
S E T
OUT for --1 V ±0 .1
V ;
the n rotate th e co n trols fully cloc k -
wise and check for +1 V -0 .1
V .
i . Disco n nect th e
V oltmeter an d Cable Assembl y from
t
h e OFFSET O U T jack .
F
ig . 5-8 . Αι εστt αη e η t location, ste p 7 .