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Section TV
Paragraphs
4-9 to 4-14
d.
Set the 1615-A Capacitance
Bridge controls
as
illustrated in Figure 4-4.
e.
Connect
the 1311-A Audio
Oscillator
OUTPUT
and the 1615-A Capacitance Bridge GENERATOR
terminals
with
input cable
GR
CO 274 - NL.
Connect
the 1615-A's
DETECTOR
connector and
the 1232-A
Tuned Amplifier and Null Detector
with cable GR CO 874-R22A.
f,
Turn on the power switches of the 1311-A
Audio
Oscillator and 1232-A
Tuned Amplifier and Null
Detector.
g.
Connect
the measuring cable to the1615-A UN-
KNOWN
terminal with GR- BNC
(receptacle)
adapter.
HP Part No.
1250-0850
and measure
the residual capacitance of the measuring cable
by manipulating 1615-A
capacitance controls.
Let the obtained value x.
x is usually 0. 7pF to 1, ZpF.
4-9.
Set the 4440B as shown in Table 4-2,
measure
the capacitance between the 4440B terminals.
Check
thal the 1615-A capacitance reading is withinthe upper
and lowerlimits
shown in Table 4-2 and that the dis-
sipation factor reading is less than . 001.
NOTE
When
measuring
higher
values
of
the
4440B
(greater
than
0.1uF),
the
resis-
tance of the measuring
cable
increases
the series loss resulting in an
incorrect
Dissipation
Factor reading of the 1615-A.
In this case, use 3 TERMINAL
(binding
post) position
of the 1615-A
Terminal
Selector
and
connect
the 4440B to these
terminals
with
three pieces
of wire with
resistance
as small as possible
(thicker
than AWG
#20,
shorter than 4 inches).
UNKNOWN
UNKNOWN
>
3
TERMINAL
H
2
L
TERMINAL
GND
Figure 4-4.
1615-A Capacitance Bridge Setting
4-2
Model 4440B
4-10.
ADJUSTMENT
4-11.
When the adjustment of the variable
capacitor
is necessary,
the testing plate (Figure 4-2) should
be
installed according
to the following
steps,
and
an
adjusting screw
driver with long insulator rod
should
be used.
The
Capacitance Bridge reading while
ad-
justmeni is being made should be equal tothe
reading
alter the adjustment
is completed.
a.
Remove
the top cover by taking out two
screws
on the rear.
b.
Remove
theinside cover plate by takingout
two
Screws at the center of the right and left
sides
of the plate.
c,
Install the testing plate (Figure 4-2) in place of
the inside cover.
Fasten
it with the two screws
taken out in step b.
4-12.
Setthe
Capacitance
Bridge same as indicated
in paragraph 4-8.
4-13.
VERNIER
ADJUSTMENT
a.
Setallthe dials of four decades
to zero, and the
vernier scale to 40pF.
b.
Set 1615-A capacitance controls
(40 + x)pF, and
adjust C26 to minimize
the meter deflection of
the 1232-A "Tuned Amplifier and Null Detector"
using the adjusting
driver.
Rotate the vernier
dial,
and set vernier scale to 140p F. Make the
1615-A
Capacitance
Bridge
balance by manip-
ulating
capacitance
and
dissipation
factor -
conductance controls,
with
D MAX knob set
at
0. 01, and
read
the capacitance and dissipation
factor.
The reading should be between
(135. 65
+ x)pF and (143.35 + x)pF.
Dissipation
factor
should be less than . 001.
c.
Set vernier
scale to 120pF,
100pF,
80pF
and
60pF,
make
the 1615-A
Capacitance
Bridge
balance at each setting
and make
sure that the
reading is within the limits listed in Table 4-2.
d.
Set vernier scale to 40pF again.
4-14.
FOURTH
DECADE
ADJUSTMENT
a.
Without
moving
vernier
scale,
set the
fourth
decade dial of 4440B to 1 (equivalent to 100p F).
b.
Set capacitance control of 1615-A to (140 + x)pF.
Adjust C18and manipulate the dissipation factor
control for the minimum deflectionon the 1232A
meter.
Dissipation
factor
readout
should
be
less than , 001,
c.
Set the fourth
decade
dial
to 2 (equivalent
to
200pF),
set capacitance
control of 1615-A
to
(240 + x)pF and balance the1615-A by following
the same steps
as indicated in step b. with
the
adjustment of C20.
4440B-1
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