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Section V
Model 654A
DISTORTION
ANALYZER
TEST
OSCI
LLATOR
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TERMINATION
1-
~:
6~"A·
8
-
1899
hp
1I048C
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-----------
I
Figure 5-10.
b. Set the 654A
controls as
follows:
FREQUENCY dial.
.
.
.
. . .
.
.
.
.
.
. ....
1
FREQUENCY RANGE ....
..
...........
XIO
OUTPUT LEVEL dBm
.
.
.....
.
........
+10
,0
IMPEDANCE
...........
..
.......
50 UNBAL
AMPLITUDE ..........
.
Adjust for
+
I dBm
on 654A
meter.
c.
Verify distortion of
greater
than 40dB below the
fundamental frequency by checking the
d:,lOrtion
at
the following
frequency settings of
the
654A:
I) FREQUENCY dial at 1,2
,
5,8 and
10 for
each
FREQUENCY RANGE
switch setting, X
10,
XIOO, XIK,
and
XIOK.
2)
FREQUENCY dial at I,
2 and 5
for XIOOK
setting of
FREQUENCY RANGE
switch.
d. Disconnect the
654A
from the distortion analyzer
and connect
the
654A
to the
wave analyzer
(remove 50 ohm
fecdthru termination).
e.
Set the
654A
FREQUENCY RANGE
switch
to
X
I M and the FREQUENCY dial to I.
f Tune the wave analyzer to I MHz
and
note the
level (in dB)
of
the
654A
fundamental frequency
as
indicated on the wave
analyzer
meter.
g. Tune the
wave
analyzer
to the
seco
nd
and
third
harmonics
of the 654A frequency
and record the
difference (in
dB)
between
the level of each
harmonic and the level
of
the
fundamental.
Calculate
the
total
harmonic
di stortion
(calculation below) which
should
be
at
least
40dB
below
the fund amental frequency level.
----------NOTE----------
If both harmonics are more than
43dB
below
the
fundamental,
the
total
harmonic distortion
will be
more than
40dB
down
and
it
will
not
be
necessary
to make the
following calculation.
I) Ascertain the difference
between
the
two
harmonic levels (in dB).
5·10
Distortion
Check
2) Using
the
chart
below (Figure 5-12),
determine the dB to be added to the
largest
harmonic
level.
3)
Add this
amou
nt to the largest har-
mo
nic
level. Th is total
should
be
~
40 dB
below the level in
step
f.
Example:
If two
harmonics
with levels
of
-42dB
and
·48dB
are measured,
the
difference is A8
·(-42)
=
·6
.
Observing
the
chart
this corresponds to an added
level of 1.0dB.
Adding
this to the
largest harmonic level
(-42d
B)
gives
A2
+1
.0
=
AldB.
h.
Set the
654A
frequency to
5MHz;
tune the
wave
analyzer
to 5MHz
and repeat steps f and g
to
measure the total harmonic distortion
at 5MHz,
which
should be greater
than 34dB below the
fundamental.
I.
Set the
654A
frequency to 10MHz; tune the wave
analyzer
to
I
OMHz
and
record the level indicated
(in dB) on the
wave analyzer
meter
.
J. Tune the wave analyzer to
20MHz and
measure
the distortion
which should
be
at
least 34dB below
the level recorded
in step
i.
k. Perform the
adjustment of
Paragraph
5·51
if the
tolerances
are
not met.
5-36. HUM AND NOISE CHECK.
a.
Connect the equipment shown
in
Figure 5·11.
Figure
5·13 shows
the
parts
required to
build the
10MHz Low-Pass Filter.
b. Set the
654A
controls as
follows:
FREQUENCY dial
.
...
.
.Extreme Clockwise
FREQUENCY RANGE.
.X1K
OUTPUT LEVELdBm
.
.
..
. +10,0
IMPEDANCE.
...
50
UNBAL
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