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__ _
_______
ldel654A
,
I.
.
'igure 5·5.
at
10kHz,
....
X1K
.
.
.
..
.10
...
+10,0
:0 UNBAL
Adjust
for
54A meter
)nnect the
JTPUT
to
~CORDER
ER
MODE
ion.
:quency
as
f between
OFFSET
n
on
the
uatio
n.
to
return
n
to
OdB
e
-ldBm,
on.
to
return
n
to
OdB
!
+ldBm,
Model
654A
k. Adjust
the
654A
to 10MHz
and
reset the
AMPLITUDE
con
trol
for
OdBm indication on the
654A meter.
I.
Repeat steps d
throug
h j
of
this paragraph to
check tracking
at
10MHz.
m. These checks verify
meter
tracking accuracy of
+j.0.05dB; perform the
adjustments of
Paragraphs
5-58 through 5-60 if the li
mits are
not met.
5-22. ATTENUATOR ACCURACY CHECKS.
5-23. MEASUREMENT
PROBLEMS.
5-24.
The tes
t
set up for
the atlen uator
checks
is
critical.
Improper
grounding
can
give
att
enua
tor measurement
errors of
great
er
tllan
J
d
13
Ground
loops
can
be
eliminated
by usin
g
an
adequate
Iso
lati
on
Transformer
connected
between
tile power lin
e source
:lI1d
tllC 654A as shown in
Figure
5-6.
5-25. [f the 654A att enuators
do not appear
to be within
the limits given in the followin
g
ch ecks
,
ca
refully
check
the
test
setup
before
troubleshooting
the attenuators,
the
placement of the
shield around
th
e
654A attenuators
is
extremely
critical
and
,
if
disturbed, ca
n advers
ely
affect
the
high frequ enc
y
response of
the attenualors
(see
Paragraph
5-97).
flS
(lLATlOr. J T
RANSrORMi
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i
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115VAC
115VAC
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TRACKING
OSCI
LL A T OR
,
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1
I
hP313A
I DB/STEP
WAVE
ANAL
YZ
ER
ATTENUATOR
hp312A
, hEr
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.
~
_
750
FEE 0 -
T HRU
I
TERM I
NAT
IO
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hp
1I094A
Figure 5 -6. Attenuator Accuracy Checks
5-7
:
10
DB
/ S
T
E
P
OUL--,"U<r>
M:!JCJnl1-<'
ATTENUATOR
'
:
hp
355D
:
.[@1
750
TO
500
'-----u
IMPEDANCE CONVERTER
SEE
FI
GU
RE
5-7
Section
V
5-26. IOdB-STEP ATTENUATOR CHECK.
- - - - - - NOTE - - - - -
See
Paragraphs 5-24 and 5·25 before
making
th.is check.
a. Connect
the
equipment
shown
in
Figu re
5-6
.
(Figure
5-7 shows
the parts required to build
the
75
ohm
to
50 ohm
impedance
converter).
Use the
10dB/s
tep
external
attenuator
(with
known
accuracy at 300kHz
and 10MHz)
,
do
not
connect
the
IdB/s
tep
attenuator at
this
time
.
b.
On the rear panels
of
the instrument
s co
nnect the
3 I
2A
Wave Analyzer RECORDER OUTPUT
to
the
3J3A
Tracking
Oscillator
RECORDER
INPUT
.
Set
the tracking oscillator METER MODE
switch
to
EXPAND
312A.
c. Set
th
e
654A
controls as follows:
FREQUENCY
dial. .
.
.
. . . . .
. .
.
.
...
3
FREQUENCY RANGE
.......
.
.......
XIOOK
OUTPUTLEVELdBm .....
.
..........
+10,0
IMPEDANCE.
.
.
. . .
.
. . .
.
.
..
. ....
150 BAL
AMPLITUDE
.
.
.
.
.
.
.
.
.
. .
.
.
.
Adjust
for
OdBm
on 654A
met
er.
d.
Set
lhe external
atlenuator
to
-90
dB position and
the
external
amplifier
gain
10
+40dB.
1
:
AMPLIFIER
I
hp
461A
i
II
g
II
i
0
0
( 3 - - - -
II
II
I£]
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I
~
I
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_
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~
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!
@
!
.,
o
©
©
$
00
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