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Section V
4) Repeat
step
5-55d as often as necessary until
tolerances are met
at
both 5
and
10
settings
of
the FREQUENCY dial. If S2C6 does not have
sufficient
range,
change
the
value of
S2C7* in
accordance
with Table 5-4 ;similarly, for S2C 12
change S2CI5*
.
e.
Set the 654A FREQUENCY dial to I; the
coun
ter
should
indicate 1000:t 20 kHz
and
A2TP2 voltage
should
be between - 0.3 V to - 0.4 V; if frequency
or
A2TP2
voltage
is
not within tolerance
,
pad
range resistors S2R8* and S2R16*
simultaneously
in accordance with Table
5-4.
- - - - - - N O T E - - - - - -
It may be necessary to set the
frequency
high
at
10
on
dial in
order for
the dial to
track.
f.
Set
the
dial to 10
and repeat steps c and
d if
necessary.
g.
Check
frequency tracking of the dial at the
settings
given
in Table
5-2 for
th
e
XIM range; if
any
of these
are
not within tolerance, repeat
steps
c
through
g of
this paragraph.
A2TP2
voltage
should
be within
-
0.25 to - 0.42
volts over
the
entire
range.
5-56. XIOOK RANGE ADJUSTMENTS.
a. Connect the
equipment
as shown in Figure
5-15.
Set the
654A controls
as in Paragraph 5-50b
except set
FREQUENCY RANGE to XIOOK
and
FREQUENCY dial to I.
b. Note the A2TP2
voltage which should be
between
- 0.3 V to - 0.4 V:
set
the FREQUENCY dial
to
10
and adjust
S2C4
and
S2C I 0
for
u
counter indica-
tion of
I
MHz :t
20
kHL
and
an A2TP2
vol
tage as
noted above. If S2C4 does not have
sufficient
range,
change
the
value of
S2C5* in
accordance
with Table 5-4;
similarly, for
S2CIO,
change the
value
of
S2C
II
*.
c. Check
the FREQUENCY dial tracking using the
settings and
tolerances
given
in
Table
5-2
for
the
XIOOK range. [fnot in tolerance, repeat step b
but
set
the frequency (with dial
at
10) toward
s
the
lower
or
upper limit
of
the tolerance
given
in
Table
5-2 so that
the dial will
track as
required.
5-57. OUTPUT WAVEFORM CHECK.
a. Connect
the
654A
50 ohm output to the
oscilloscope:
terminate
the
cable
from the 654A
with
a
50
ohm
feedthru.
5-16
Model
654A
b. Set the 654A controls
as
follows:
AMPLITUDE ........
extreme
counter-clockwise
OUTPUT LEVEL dBm
..
...
. extreme
clockwise
[MPEDANCE .. _... ___
.
.
.
.
.
.50 UNBAL
c.
Check the 654A output waveform for
spurious
oscillations
or
visible
distortion:
check
all
frequencies by
sweeping
the FREQUENCY dial
across
the whole range
at
each FREQUENCY
RA NGE
setting.
[I'
distortion
or
spurious
oscillations
occur, eliminate
by
changing the
value
of
A2C8*.
- - - - - - N O T E - - - - - - - -
[f A2C8* is
changed
it may be necessary
to
recalibrate
the
XI
M
and
XIOOK
ranges
.
5-58. METER TRACKING AND AIVIPLITUDE CONTROL
ADJUSTMENTS.
5-59. METER RANGE ADJUSTMENT.
a. Set the 654A
controls
as follows
:
FREQUENCY dial
_..
....
.
.....
......
1
FREQUENCY RANGE
_..
.. XJK
OUTPUT LEVEL dBm
....
.
...
_
_...
+10,0
[MPEDANCE.
'.
..
.
.
.
.
.
.
.
... 50
UNBAL
b.
Adjust
A3RI8
(Mcter Cal)
to its extreme
clockwise position.
c.
Adjust A3R7 (Meter Offset Cal) so that the
AMPLITUDE
control
has
sufficient
range to
exceed
the maximum
meter
deflection at both
ends of
the meter
scale
.
d.
Adjust the 654A AMPLITUDE
control
for
a meter
indication
of -I
dBm.
e.
Connect
the
eqUipment
shown in Figure
5-16 and
set
the
external attenuator
for OdB
attenuation.
f. Adjust the reference
supply
for null indication
on
the
de null voltmeter (which
should be
set
to
either
the
30uV
or I OOuV range).
g.
Set
the
external
attenuator
to
-2dB
position
and
adjust
the
654A AMPLITUDE
con
trol
to
return
the
de null
voltmeter
indication to null.
h. Adjust A3RI8
(Meter Cal)
until the 654A meter
indicates +ldBm.
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