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LBI3
I072
TEST
PROCEDURES
These
Test
Procedures
are
designed to
help you to service a receiver that is
operating---but not properly.
The problems
encountered
could be
1ow
power, poor sensi-
tivity,
distortion,
1l-miter not operatlng
properly,
and
1ow
gain. By following
the
sequence
of test steps starting with Step
1,
the defect
can be
quickly localized.
Once
the defective stage is pin-pointed, refer to
the "Service
Check"
listed to correct
the
problem. Additional corrective
measures are
included in the Troubleshooting
Procedure.
Before starting with the Receiver Test
Pro-
cedures, be sure the receiver is tuned
and
aligned to the proper operating
frequency.
TEST
EQU
IPMENT
REQU IRED
o
Distortion
Analyzer
O
Signal
Generator
a
6
dB
attenuation pad,
and
4.0
ohm,
5 Watt resistor
PRELIM
INARY
ADJUSTMENTS
l.
A.
STEP
I
AUDIO
POWER
OUTPUT
AND
DISTORTION
TEST
PROCEDURE
tr'leasure
Audio
Power
0utput as follows:
Apply a
1000
mj-crovo1t,
on-frequenc.v
test signal
modulated
by 1,000 hertz
with 15.0
kHz
deviation to
antenna jack
J601.
B
.
Wi
th 3 l{att
Speaker
Disconnect speaker
J904.
Connect
a 4.0
ohm, 5
Watt load resistor
across J904-7 &
Z.
Connect
the Dlstortion Analyzer input
across the resistor as
shown.
C.
D.
Adjust the
VOLUME
control for 3
Watt
output 5.46
VRN'IS
using the Distortion
Analyzer as a voltrneter.
lilake
distortion
measurements
according
to manufacturerts instructions.
Read-
ing should be less than 5%. If the re-
ceiver sensitlvity
i-s to be
measured,
leave all controls
and equipment
as
they
are
,
SERVICE
CHECK
If the distortion is
more
than
5%, or
maxinun
audio output is less than
3
Watts,
make
the follorving
checks:
Battery
and
regulator voltage---1ow
voltage
wj-11 cause
distortion.
(Refer
to Receiver
Schematic Diagram
for volt-
ages
. )
Audio Gain (Refer to Receiver Trouble-
shooting
Procedure).
FM
Detector Alignment (Refer to
Re-
c
e
iver
A1i
gnrnent
)
.
E,
G.
A.
B.
F.
I
:
(
I
I
1
1
r
:
D.
S
s
1
1
t
l
i
E.
1
I
1
l
(
C
l
PUSH MONITOR
PUSHBUTTON
''in''
to
Squelch
Circuit.
Do
not adjust
control.
defea
t
squelch
I
€
I
F.
i
I
c
RECE
IVER
TEST
18
PROCEDURES
fssue
1
These
procedures are written around
the
Heathkit Dj-stortion Analyzer. If
a
Distortion Analyzer other than
the
Heath IM-12 1s
used,
measure
the sensi-
tivity
and
rnodulation acceptance
band-
width in
accordance
with manufacturer's
instructions.
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