Motorola GTX Service Manual page 30

Theory of Operation
Transmitter
VOLUME
VOL
CONTROL
ROTARY
ROT1
SWITCH
& LEVEL
ROT2
ENCODER
H FILTER
TXB+
ACC.
AUDIO
RX_AUDIO
CON.
PA
MUTE
INT. SPKR
MIC.
ACC.
PREAMP MIC_IN
CON.
INT. MIC
28-PIN
CONNECTOR
FROM RF SECTION
2-2
935-941MHz
FRONT-END
1ST MIXER
MODULE
RX_INJ
ANTENNA
SWITCH
PWR_REF
POWER
CONTROL
TX_INJ
POWER
AMPLIFIER
896-902 MHz
TEMPUS_D/A
PWR_REF
RED
YELLOW
HEAR CLEAR
5R
MIC_EN
4 X 4 KEYPAD
ASFIC
DISPLAY/KEYBOARD DRIVER
PARALLEL BUS
ROM 128K
RADIO FUNCTIONAL BLOCK DIAGRAM
68P02948C90-O
GTX/GTX LTR/LTS 2000 Portable Radios Service Manual
RF & AUDIO SECTION
45.1 MHz
2ND MIXER &
IF
DEMODULATOR
889.9-995.9 MHz
16.8 MHz
REFERENCE
OSCILLATOR
16.8 MHZ
PRE-
AMP
SCB4
SCB3
DAC_SEL
D/A
SCB2
SCB1
LOGIC SECTION
SERIAL
8-DIGIT
LCD DISPLAY EEPROM 4K
VOL_SENSE
RAM 8K
DET_AUDIO
28-PIN
LOCK_DET
CONNECTOR
SYNT_EN
TO LOGIC SECTION
2.1 MHz
MOD_IN
SPI_DATA
SPI_CLCK
SPI BUS
µPROCESSOR
PTT
HC11K1
MONITOR
OPT
LOCK_DET
SYNT_EN
PEND_EN
SCI
ROT1
ROT2
DAC_SEL
February 1997