Performance Check/ Calibration-Type
453/R453
~
Six divisions
of
~
1
deflection
at
50
kHz
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,.___
_,
1
Reduced
to
4.2
1
-+-I
divisions
at
- 3
dB
~
point
Fig.
5-43.
Typical
CRT
display
when
checking
external
horizontal
bandwidth
(double
exposure).
65.
Check
Trace
Finder Operation
a. Reconnect the dual-input coupler to the Channel 2
INPUT
connector.
b.
While holding the
TRACE
FINDER
button depressed,
rotate the Channel
l,
Channel 2 and Horizontal
POSITION
controls and the
CH
l and
CH
2
VOLTS/DIV
switches
throughout their ranges.
c.
CHECK-CRT display remains within the graticule area.
d.
While holding the
TRACE
FINDER
button depressed,
adjust the positioning controls
until
the display
is
centered
about the graticule center
lines.
Then, increase the X and Y
deflection factors
until
the display
is
reduced to about two
divisions vertically and about four divisions horizontally.
e. Release the
TRACE
FINDER
button.
f.
CHECK-CRT display
must
remain within the graticule
area.
g. Reduce the
INTENSITY
control to a normal setting
(about midrange).
h.
Disconnect all test equipment.
66.
Check
Chopped Operation
a. Change the following control settings:
MODE
TRIGGER
A and B
TIME/DIV
HORIZ
DISPLAY
CHOP
NORM
.5
µ,s
A
b. Position the traces about four divisions apart.
c.
Set the A
LEVEL
control for a stable display.
d.
CHECK-Each cycle for duration of 3.4 to 5 divisions
(500
kilohertz,
+20%;
see
Fig.
5-44).
e. CHECK-CRT display for complete blanking
of
switch-
ing
transients between chopped segments (see
Fig.
5-44).
5-40
-+-J
Chopped
repetition
k-
l
rate
correct within I
I
these
limits
!
i
..
Switching
transient
blanked
out
A
I
............
\
"
..
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..
J
.~
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.
. .
..
·-
1
.
"T "T "T
\
1 •
J
.
\
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~
I\.
'-"'
\....
Fig.
5-44.
Typical
CRT
display
when
checking
chopped
repetition
rate
and
blanking.
67. Check/ Adiust Calibrator Repetition 0
Rate
:a.
Connect the l
kHz
CAL
connector to the Channel 1
INPUT
connector
with
an 18-inch
BNC
cable.
b. Connect the time-mark generator
to
the Channel 2
INPUT
connector
with
a 42-inch
BNC
cable.
c.
Set the time-mark generator for one-millisecond mark-
,.,.,,,,
ers.
d.
Change the following control settings:
CH
l
VOLTS/DIV
CH
2
VOLTS/DIV
MODE
A and B
TIME/DIV
50mV
.2
ALT
l
ms
e. Set the A
LEVEL
control for a stable display.
f.
Position the display so the tips
of
the markers fall
just
below the
rising
portions of the square wave
(see
Fig.
5-
4SA).
g. CHECK-For one cycle of calibrator waveform for each
marker (see
Fig.
5-45A).
h.
ADJUST-Calibrator Frequency adjustment,
Tl
255
(see
Fig.
5-458),
for one cycle of calibrator waveform for each
marker (preliminary adjustment).
1.
Set the
TRIGGER
switch to
CH
l
ONLY.
j.
CHECK-
CRT
display for slow drift or
no
drift of the
time
markers.
k.
ADJUST-Tl
255
for
minimum
drift of time markers
(final
adjustment).
I.
Disconnect the time-mark generator.
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