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FIXED
SQUELCH
ADJUSTMENT
1.
Connect
a signal
generator
to
antenna
jack
J601.
2,
Press
in
and
hold in the
MONITOR
pushbutton
and
adjust the signal generator for
a
nominal
9
dB
SINAD
signal,
3. Set
SQUELCH CONTROL
pushbutton
to its "out" position.
4. Adjust
squelch
control
R607
to
maximnm
squelch"
Receiver
must be
muted.
5. Adjust
squelch
control
R607
slowly
untit receiver
unmutes.
6.
Check
that the
squelch
opens
at an input signal level
correspondlng
to 8
dB
SINAD
(+1
dBs).
LBI3LA72
RECEIVER
ALIGNMENT
PROCEDURTS
Issue
I
Lz
STEP
METERING
TEST
POINT
PROBE
TUNING
CONTROL
(s)
PROCEDURE
T,RONT
END
ALIGNI4ENT
7
8
o
10
11
t2
TP5O1
TP5O
1
TP5O
1
TP5O
1
TPSO
1
Rx
RF
DETECTOR
Rx
RF
DETECTOR
Rx
RF
DETECTOR
Rx
RF
DETECTOB
Rx
RF
DETECTOR
L405
,
L406
L407
L402,L40L
66
g;+€
L405,L410
L4O7
ft4i?
Connect
signal generator to
Antenna
input
jack
J601. Verify
Rx RF
Detector
Probe
is
connected
to
TP501
and
VOM. Adjust signal generator
to
RF
channel
frequency. Adjust output level of
signal generator for a
VOM
reading
between 0.b
and
1.0 Volts.
Detune L405 and
L4O7
as
nuch
as
possible.
Tune
L406
through
entire
range
while noticlng
peak
readings
on
VOM.
Adjust
L406
for
maximun
meter
reading, reducing the output Ievel of signal
generator
as required.
DO
NOT
Read.just
L406
after peaking, Alternate$ ;E;djust
L4O7
and
L405
for
maxinum
VOM
reading.
Alternately adjust
L4O2
^nd,1,401
for
maximum
VOM
reading.
Reduce
generator output to
maintain a
VOM
reading of 0.5 to 1.0 Volts.
Carefully adjust L355 (!Il4
turn) for
maximum
meter reading.
Alternately adjust
L4O9,
L4O7
and L405
for
maximum
meter reading.
Remove
all test
equipment.
DETECTOR/AUDIO
ALIGNMENT
14.
15.
1A
Audio
Ou
t
put
P903-
3
L504
Lii01
R52
1
,"s.c
I
qrrt.
Apply
a
1000 uV RF
slgnal
modulated
rej-th
1000
Hz to
antenna
input jack J601.
Connect
external speaker leads J91O-3, JgIO-7 to
a
four-ohm resistive
1oad.
Set audio level
control
R521
and
volume
control
R634
to
mid
position.
Connect AC
voltmeter/distortion
analyzer across
four
ohm
load. Adjust
L504
for
maximum
meter
reading.
Reduce
voLume
control
as necessary to keep output voltage
from
exceeding
2.0
VRIIS.
Adjust
volume
control for a level of 2.0
VRMS
on
AC
voltmeter.
Note
the position of
tuning
slugs in
L501 and
L409,
Slowly
adjust
L501
and
L4Og
+l
/4 turn for
minimum
distortion
on
distortion
analyzer.
If
no
improvement
is
noted
return slugs to originat posltion.
Connect AC
voltmeter having a
minimum
input
impedance
of 1
megohm
to P903-3. Adjust
audio
leve1 control
R521
for a meter reading of
300
nV
RMS
+5
mV.
Reconnect
AC
voltmeter across external
speaker
leads, J910-3
(SPKR
HI) and J910-7
(SPEAKER
LO). Adjust
volume
control for 3 Watts
(3.46
VRMS
across
4
ohrn
load),
Measure
audio distortion
using Distortion
Analyzer. Distortion should be less than
5%.
Disconnect
a1l test
equipment.
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