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4.2.7
Frequency
Calibration
29.
Set
FREQ HZ
to
X10K,
FREQ
DIAL
to
10,
VERNIER
to
CAL,
and
adjust
R269
to
obtain
100
kHz ±100
Hz.
30.
With
FREQ
HZ
still
at
XlOK,
FREQ
DIAL
fully
clockwise,
VERNIER
fully
counterclockwise,
and
adjust
R87
to
obtain an
output
of
75 Hz ±5
Hz.
31.
Rotate
VERNIER
to
CAL
position.
The
output
fre*
quency
should be
less
than
1
kHz.
32.
Set
FREQ HZ
to
XIM,
FREQ
DIAL
to
9,
and
adjust
Cl
to obtain
an output frequency of
9
MHz
±10
kHz.
Check
frequency accuracy
from
1
to
10
of
ttie
DIAL
and
readjust
Cl
to
split
the
error
if
necessary.
33.
Set
FREQ HZ
to
X100K,
FREQ
DIAL
to
10,
VERNIER
to
CAL,
and
adjust
CIO
to obtain
1
MHz
±1
kHz
at
the output.
Check
frequency accuracy
from
1
to
10 of
the
DIAL
and
readjust
Cl
to
split
the
error
if
necessary.
34.
Set
FREQ
DIAL
to
10,
VERNIER
to
CAL.
35.
Set
FREQ HZ
to
XI
K, adjust
R268
to obtain
10
kHz
±10
Hz.
36.
Set
FREQ HZ
to
X100,
adjust
R267
to obtain
1000
Hz
±1 Hz.
37.
Set
FREQ HZ
to
X10,
adjust
R84
to obtain
100
Hz
±0.1 Hz.
4.2.8
Time Symmetry Adjustment
38.
Refer
to
the following
test
set-ups
during these
cali-
bration
instructions.
MODEL
144
500HM
TEK544
TERM.
CH.
A (NORMAL)
50(2
OUT
O-
'
<
-O
-O
CH.
B(INVERTED)
Trigger;
Internal
Display:
Alternate
Time
Base:
.1
ms/division for
1/1000th
of
X100K
range.
Figure 4-S
-
Time Symmetry
Measurement
Test Set-Up
39.
With
50S2
OUTPUT
connected
to the
oscilloscope;
set
FREQ HZ
to
X
100K,
FREQ
DIAL
to
full
clock-
wise extreme,
and
WAVEFORM
SELECTOR
to
SQUARE
WAVE.
40.
Adjust the scope controls
for a display
speed of
.1
ms/cm
and
adjust
VERNIER
control
until
the
oscilloscope screen
is
filled
by one complete
cycle.
41.
Alternately adjust
R123
arxl
R125
for
optimum
sine
symmetry,
while
keeping
the
total
time
period
constant.
4.2.9
Output
Amplifier
Adjustment
42.
With
the 50(2
OUT
connected
to the oscilloscope
using a
50(2
±1%
termination;
set
FREQ HZ
to
X
100.
FREQ
DIAL
to 10,
WAVEFORM
SELECTOR
to
TRIANGLE
and
step
attenuator to
0
dB.
43.
Set
30
V
P-P
MAX
control
fully
counterclockwise,
and
adjust
R188
for
amplitude
symmetry
about
ground.
44.
Set
30
V
p-p control
fully
clockwise,
and
adjust
R228
for a
15
V
p-p
output
amplitude.
45.
Set
WAVEFORM
SELECTOR
to
SQUARE
WAVE,
and
adjust
R66
for
+7.5
V
and
R63
for
—7.5
V
peak
amplitude. (15.0
V
p-p.)
4.2.10
High
Frequency Response Adjustment
46.
Set
FREQ HZ
to
X
IM,
FREQ
DIAL
to
1,
and
WAVEFORM
SELECTOR
to
SQUARE
WAVE.
47.
Adjust
C95
for best
square wave,
without
peaking,
from
5
V
p-p to
10
V
p-p
output
amplitude.
48.
Set
WAVEFORM
SELECTOR
to
SINE
WAVE. FREQ
DIAL
to
10.
49.
Adjust
C48
to obtain
14
V
p-p
output
amplitude.
4.2.11
Sweep
Board Adjustment
50.
Set
MODE
selector to
CONT
and
SWEEP
Tl
ME
selec-
tor
to
OFF.
51.
Connect
oscilloscope
probe
to the
sweep output
at
the junction of
R52
and R53.
52.
Adjust
R43
to
set
output
at
—20 mV.
53.
Set
SWEEP
TIME
selector
to
100
mS/10
mS
and
the
VARIABLE
to fully
CW.
4-4
4^3
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