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540B
b.
GALV switch OPEN.
SENSITIVITY switch LOW.
POWER switch
ON.
c.
Adjust
R6 for a
1.
2 ±0.1
volt
peak-
to-peak wave-
form displayed on the oscilloscope.
d.
Remove oscilloscope connections.
e.
Connect an electronic counter between the lead of
R5 nearest Ql and the negative end of Cl.
f.
Adjust the core
of
Tl for a 2500 ±5
Hz
indication on
the electronic counter.
(The core of T1
is
adjust-
able from the land pattern side of the circuit board.
Access to the adjustment is through the opening left
from removing the battery pack. )
g.
Remove all test connections and set the POWER
switch to OFF.
h.
Re
-
install the battery pack and top cover on the
Model 540B.
4-16.
TUNED CARRIER AMPLIFIER
ALIGNMENT.
Remove the side cover on the galvanometer side of the
Model
540B.
Refer to Figure
4-
4 for adjustment and
connection locations. Connect equipment as shown in
Figure
4-
3 and use a 1 megohm
±1%
resistor for Rx.
Proceed as follows:
a.
Connect the oscilloscope vertical input to the
junc-
tion of R34 and R35 (junction E)
.
Connect
oscillo-
scope ground to T2 mounting screw.
b.
Set the oscilloscope controls for 100 millivolts per
centimeter of vertical deflection and 50 micro-
seconds per centimeter of horizontal deflection.
c.
GALV switch OPEN
.
.
SENSITIVITY switch LOW.
POWER switch ON.
d.
Adjust power supply for 3 volts ±100 mv (3 ua
input).
e.
With a
non-
metallic screwdriver, adjust the core
of T3 (adjustment H) for a maximum 5 kHz signal
level, as seen on the oscilloscope.
f
.
With a
non-
metallic screwdriver, adjust the core
of Ll (adjustment J) for a maximum deflection to
the right on the GALVANOMETER meter
(approxi-
mately 20 ±5%
of
full scale)
.
g.
Repeat steps (e) and (f) for a maximum signal
indi-
cation on both the GALVANOMETER meter and the
oscilloscope.
4-
17.
TUNED CARRIER AMPLIFIER
GAIN.
Check
and readjust,
if
necessary, the mechanical zero of the
GALVANOMETER meter. Connect the equipment as
shown in Figure 4-3 and use a 10 megohm
±1%
resistor
for Rx•
a.
GALV switch OPEN.
4-4
SENSITIVITY switch HIGH.
POWER switch ON
x
(+)
(+)
POWER
Rl6
SUPPLY
GALVANO-
METER
(-)
(-)
CIR
CUIT
(+)
DIFFERENTIAL
VOLTMETER
(-)
Figure
4-3.
ELECTRO NIC GA
LVANOM ETER CALI BRATION
E
R34/
R35
JUNCTION
J
L1
A
DJ
USTM ENT
Figure
4-4.
TUNED
CARRIER
AMPLIFI ER
ADJUSTMENTS
b.
Adjust t he
power
s
upply output for 0. 3 volt ±10
mil-
livolts (30 na input).
c.
Adjust R36 (adjustment
L) for
8
minor divisions
de-
flection to the
right on
the
GALVANOMETER
met
e
r.
d.
Reverse the polarity of
t he power supply
a
nd check
the
deflect ion of
the
GALVANOMETER m
et
e
r.
Should the deflection in
st
eps
c
a
nd d
be
unequal,
adjust R36 for
t
he
best
average
deflection in both
pol
arities (not t
o
exceed
8
±1.
0 minor
divis ions
in either
polar
ity).
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