Lay
CM1481 PCB Layout
J1/1
J1/13
D
U1
Note the position of the
on-board LINK on the
underside of the printed
circuit board.
If Alert Levels are to be
fed to an external audio
amplifier it is
recommended that the
LINK is removed so
that the ALERT output
can drive a high
impedance stage.
LINK
X1
+
U2
U3
LINK IN will drive an
external loudspeaker.
LINK OUT will drive an
external amplifier
U4
IN
OUT -AUDIO SWITCH
CM1481 Top View
Fig.4 PCB Layout
CM1481 Underside View
Component
U
1
U
2
U
3
U
4
T
1
T
2
T
3
R
1
R
2
R
3
R
4
R
5
Value
Component
R
6
R
7
R
8
R
9
R
10
R
11
R
12
R
13
R
14
R
15
R
16
R
17
R
18
R
19
Value
10.0kΩ
10.0kΩ
330Ω
47.0kΩ
47.0kΩ
47.0kΩ
2.2MΩ
Component
R
20
R
21
R
22
R
23
R
24
R
25
R
26
R
27
R
28
R
29
R
30
R
31
C
1
C
2
Value
47.0kΩ
47.0kΩ
470kΩ
10.0kΩ
10.0kΩ
10.0kΩ
22.0Ω
2.0kΩ
LINK
100kΩ
Note 1
Note 1
39.0pF
22.0pF
Component
C
3
C
4
C
5
C
6
C
7
C
8
C
9
C
10
C
11
C
12
C
13
C
14
C
15
X
1
Value
0.1µF
0.1µF
68HC705C8
FX803LS
93CO6
LM2931-5
BCX19
BCX19
BSR41
4.7MΩ
100kΩ
not used
10.0kΩ
10.0kΩ
not used
0.1µF
not used
22.0pF
not used
22.0µF
0.1µF
0.1µF
0.1µF
0.1µF
0.1µF
4.0MHz
not used
100kΩ
100kΩ
47.0kΩ
10.0kΩ
470kΩ
470kΩ
Table 2 Components List
Notes
1. Pads are made available on the CM1481 PCB for resistors R
30
and R
31
(not installed on this version) for future
hardware upgrades.
2. The pads to the audio switch are available for use with system audio. This switch operates in conjunction with the
Quiet/Open function. Refer to Radio Interface pin functions.
7
CMLMICRO [ CML MICROCIRCUITS ]
