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6.4.3
NOAA Weather Radio Receiver Audio Output Adjustment
To
adjust
the
NOAA
Weather
Radio Receiver audio output, proceed
as
follows:
a. Connect a
600Q
load
and the balanced input terminals
of
a distortion analyzer
to
the
BALANCED
AUDIO
OUTPUT
terminal block
conn
e
ctor
on
the rear
pan
el.
b.
Connect
a signal generator with an 162.5
MHz
carrier, modulated with l
kHz
at
±5
kHz
deviation,
to
the
RF
INPLfT connector
on
the
rear panel.
Set
the
signal level to 10 µV.
c.
While
observing the
meter
on
the distortion analyzer, adjust
R30
on
the
rear
panel for
0dBm.
6. 5 Troubleshooting Guide
The
intent
of
this troubleshootding guide
is
to provide voltage levels and/or waveforms to enable a
per
s
on
with
RF
experience
and
proper test
equipment
to perform repair work
by
isolating the defective
section(s) in the Recei
ve
r.
6.5.1
AM Receiver Module
Setup
Conditions:
1 . Channel Select switches at l
00
2.
RF
Frequency=
1000
kHz
,
Mod=
66
%,
Tone=
1
kHz
,
Level=
100
µV
3.
DX/LOCAL
switch
to
DX
po
sition
Table 6-1.
AM
Receiver
Test
Point
Data
TEST
POINT
DESCR
I
PT
I
ON
TP1
RSSI
TP2 PLL Phase Voltage
TP3 Demodulated Audio
TP4 LO Output
to
PLL
TPS
8
MHz
clock to µprocessor
6.
5. 2
FM
Receiver Module
Setup Conditions:
4.
4V
4.
0V
0.7 Vp-p
0.8 Vp-p
2.5 Vp-p
l . Channel Select switches at
000
( 1000)
LEVEL
WAVEFORM
DC
DC
A
V
A
V
A
V
2.
RF
Frequen
c
y=
100
MHz
,
Mod=
±75
kHz
,
Ton
e = 1
kH
z,
Level
= 20 µV
3.
DX/LOCAL
s
wit
ch
to
DX
po
sition
6-5
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