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Figure 5-9. Balance Box
5-9
)del 654A
Model 654A
Section V
Figure 5-8. Balance
Checks
r
at each
(Paragraphs
5-30
through 5-34) are not met
,
perform the
in
step
d. ac voltmeter
indication should
be below
e
external
Balance Adjustments (Paragraph 5-62 through 5-64).
12.25
mV rms.
the 654A
.
oscillator
5-30.
135 BAL
CHECK.
5-33. 600 BAL
CHECK.
lB
.
a.
Connect the equipment
,
as shown in Figure 5-8,
5·34.
Repeat the procedure of Paragraph 5-30 with the
}Od wave
using the 135
ohm
Balance Box: (the parts
followi ng
changes:
lltenuator
required to build the Balance Box are shown in
in
step
a. Use the 600 ohm Balance Box (See
Figure 5-9) the cables from the 654A should be as
Figure 5-9);
short as
possible
and
of equal length Uumper
in step
b. Set IMPEDANCE to 600 BAL;
cables, -hp- 10502-6001, which are made from 8
in
step
c. ac voltmeter indication
should
be below
in. lengths
of coaxial
cable, are suitable for this
7.75mV rms;
y
application)
.
in step d. ac voltmeter indication
should
be below
g
24.5mV
rms.
e
b. Set the
654A controls
as follows:
FREQUENCY dial
....
..
.
.
.....
.
.
.
.
.
......
1
5·35. DISTORTION CHECK.
a.
Connect a
distortion analyzer to the
654A
50
ohm
output
as shown
in Figure 5-10.
e
( ;
,
with the
I directly
ance
COIl-
I
position.
AC VOLTMETER
TEST OSCILLATOR
hp400E
EQUAL
--"
I
BALAN CE
'
CABLE
~
•
>-
BOX
-<
.
LENGTHS
,t
SEE FIGURE 5-9
~i
~
_____________
_
J
I
~
I
dB step
FREQUENCY RANGE .
.
.
.
.
...
.
...
.
.
...
XIO
IMHz
by
OUTPUT LEVEL dBm ..
.
.......
....
.
.
+10,0
Paragraph
IMPEDANCE
...............
.....
.
135 BAL
~
fofthis
AMPLITUDE
.
.
...
.......
.
..
Adjust for OdBm
on
654A
meter.
c.
Sweep the
654A slowly
over the frequency range
of
10Hz
to I MHz; the ac voltmeter indication
lrocedures
should
remain
below 3.68mV rms, verifying
balance
of greater
than 50dB from 10Hz to IMHz.
d. Sweep the
654A slowly
over the frequency range
of I MHz to 5MHz
;
the
should remain
below
balance of greater than
5MHz.
ac voltmeter
11.6mV rms,
40dB from
indication
verifying
IMHz to
5-31. ISO BAL CHECK.
5·32
.
Repeat the procedure
of
Paragraph 5-30 with the
fOllowing
changes:
in
step
a.
use the
150 ohm Balance Box (See
Figure
5-9)
;
in
step
b.
se
t IMPEDANCE to 150 BAL;
in
step c. ac
voltmeter indication
should
be below
3.87mV
rms;
BALANCE BOX
r--------------------,
I
I
I
I
RI
I
I
300
I
I
I
150
C
300
I
I
I
tJ
R2
J"
,
L -
-- - -
-- -;; -----".,:o;::;-.~
Parts
List: (All resistors
I
/8 watt metal film .)
RI,R2
300
ohms
+/-
.
1
%
-hp- 0698
-629
5
R3
150
ohms
+/-1%
-hp- 0757·0284
Rp
:
Input Impedance
Rp, +/-1
%
135
ohms
174 ohms, -hp- 06984417
150
ohms
200 ohms, -hp- 0757·0407
600 ohms
open
I
tJ
Rp
I
,
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