Racal Instruments 9081 Maintenance Manual page 83

Tune
the
UUT
to
65MHz
on range
2.
(7)
(8)
Adjust Inductor
LI6
on
the
p.c.b.
for
minimum
amplitude on
the
spectrum analyser.
(9)
Disconnect
the
+I2V
link
from pin 8.
(10)
Tune
to
67MHz
and
adjust LI5
on
the
p.c.b.
for
maximum
amplitude on
the
spectrum analyser.
(11)
Disconnect
the
spectrum analyser and connect
the
mi
Mi
voltmeter
to
the
50Qoutput,
using
RG2I3U
cable
with 'N' connectors.
(12)
Remove
the earthing link from LKI
.
(13)
Tune
the
UUT
to
50MHz.
(14)
Adjust
the
UUTVERNIER
control
to
give a reading of
+2dBm
on
the
millivoltmeter.
(15)
Adjust
Rl
36 on
the
p.c.b.
until the
UUT
meter
reads
+2dBm.
(16)
Adjust
the
UUT
VERNIER
control
to
obtain a reading of
-9dBm
on
the
millivoltmeter.
(17)
Adjust
Rl34on
the
p.c.b.
until
the
UUT
meter
reads
-9dBm.
(18)
Repeat adjustments
(|4) to (|7) until
the
UUT
and
the miTlivoltmeter
give
identical
readings
at
+2dBm
and
-
9dBm.
(19)
Disconnect
the millivoltmeter
and connect
a
modulation meter
to the
UUT 50Qoutput
socket.
(20)
Connect
a distortion analyser
to
the
modulation meter audio output.
,(21)
Set the
AM
switch
to
EXT.
(22)
Connect
a
IkHz low
distortion
audio generator
to the
AM
600Dsocket
of the
UUT.
(23)
Monitor
the
level
of the
applied IkHz
audio,
using the
HP.400E
millivoltmeter,
and
level until
the
HP400E
reads
800
mV.
(24)
Set the
UJJT
VERNIER
control
to
read
+3dBm on
the meter..
(25)
Adjust
Rl
53
on
the
p.c.b.
until the
modulation meter reads
80%.
9081
&
9082 Vol2.
5-11