
Troubleshooting
When
One
or
More
Inputs
Look
Good
Since
at
least
one
input
is
go
o d,
all
of
the
common
receiv
er
circuitry
b ey
ond
the
m
ultiplexer
is
functional.
Only
the
status
of
the
individual
sampler/mixers
andtheir
individual
signal
paths
is
undetermined.
Check
the
4
kHz
Signal
1.
Connect
a
cable
from
the
RF
OUT
to
input
R.
2.
Press
4
PRESET
5
4
MENU
5
NNNNNNNNNNNNNNNNNNNNNNN
CW
FREQ
.
3.
Use
an
oscilloscop
e
to
c
hec
k
the
4
kHz
output
of
the
sampler/mixer
in
question
at
the
A10
assem
bly
.
The
input
and
output
access
pins
are
listed
in
T
able
8-2 .
The
signal
should
resem
ble
the
w
a
v
eform
of
Figure
8-6 .
If
the
signal
is
go
o d ,
con
tinue
with
\Chec
k
the
T
race
with
the
Sampler
Correction
Constants
O."
If
the
signal
is
bad,
skip
ahead
to
\Chec
k
1st
LO
Signal
at
Sampler/Mixer."
T
able
8-2.
2nd
IF
(4
kHz)
Signal
Locations
Mnemonic
Description
A10
Lo cation
Signal
Source
IFR
4
kHz
A10P1-1,
31
A4P1-6
IF
A
4
kHz
A10P1-4,
34
A5P1-6
IFB
4
kHz
A10P1-7,
37
A6P1-6
Figure
IFW
A
VE8
here.
Figure
8-6.
2nd
IF
(4
kHz)
W
a
v
eform
8-8
Receiv
er
Troubleshooting
DRAFT
3/21/106
15:13
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