MIC
AMP
GPS ANTENNA
1
2
3
4
5
6
7
8
150K
SPEAKER
MICROPHONE
GND
XTXD
SP+
SP-
PTT
MIC
Vcc
GPS
LELEV
SHIFTER
RX
TX
ANT
3.3V
SWITCHING
REG
RIPPLE
FILTER
+3.3V
Q3, C14
IC8, Q5, D5, L3
IC2
Serial
Serial
D4
IC13, IC6
NMEA
LEVEL
SHIFTER
D6
(HM-170GP)
+3.3V
RESET
PPS
IC4
LED
DRIVER
+3.3V
Q4
DS1
SW1
SW UNIT
(HM-175GPS)
GPS
ON/OFF
Sleep
(HM-175GPS)
IC11
IC9, IC10
(HM-175GPS)
(HM-175GPS)
(HM-175GPS)
(HM-175GPS)
(HM-170GP)
CHASSIS UNIT
MIC
MUTE
IC14, Q6
(HM-175GPS)
PTT
SW1
SW UNIT
(HM-170GP)
(HM-170GP)
(HM-175GPS)
(HM-175GPS)
(HM-170GP)
NMEA
SP-
Vcc
SP+
SENS
GND
MIC
nc
6 - 2
• MAIN-B UNIT (for [HM-170GP], [HM-175GPS])