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TRC-70
CIRCUIT DESCRIPTION
open squelch.
*
Squelch control
| |
{C302 (CPU)
|
| |
R305
3
|
PA2
| |
R359
|
| | dvsa
r
|
-—e
al
| |
D0~D7
|
1C3 SQL
| |
|
KCXO2
so
| |
|
ah
>
SQL
R310
KIS]
554
pa 22
'i
|
4
| |
C146
PC3
| |
$3
1¢300
| |
TX-RX UNIT xs7s470-21) | _
CONTROL UNIT (X53-3280-21) | | sx.2x UNIT (X57-3470-21)
Fig. 12 Squelch control circuit
*
Noise bianker switching
1C302
The CPU inputs the NB SW status by key scan.
PAa3}¢-—+w——
ae
NBI
When the NB SW is pressed, the display changes
from OFF to NB1 to NB2 to OFF, and the NB1/NB2
port is controlled as listed in Table 3.
R307
When the display is NB2, both NB1 and NB2 oper-
pc7}eww-——— NB2
ate.
Display | NB1
NB2
Ot
KS PB6
OFF
L
L
NB1
H
L
D
$3. PC3
NB2
H
H
Table 3
1€300
14
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