Main Board; Figure 3-3. Transceiver (Vhf) Block Diagram (Power And Control Omitted) - Motorola APX 1000 Detailed Service Manual

3-4
3.1

Main Board

The main board performs the transmitter and receiver functions necessary to translate between
voice and data to modulated radio-frequency (RF) carrier at the antenna. The main board contains
all the radio's RF circuits for the following major components:
• Receiver
• Transmitter
• Frequency Generation Unit (FGU)
• Controller
Figure 3-3, Figure
and 900 MHz transceiver block diagrams.
GPS
VHF

Figure 3-3. Transceiver (VHF) Block Diagram (Power and Control Omitted)

3-4, Figure 3-5 and
Log
Amp
Harmonic
Filter
Digital
RF Atten
coupler
Rev
Power
Detector
15dB Step Attn
*
16.8MHz
TRIDENT IC
PRESCALAR
BUFFER
16.8MHz
BUFFER
LNA
VHF
Figure 3-6 illustrates the VHF, UHF1, UHF2, 700/800 MHz
Antenna Switch
FET
Driver
Amplifier
LOOP
RX VCO
FILTER
PRE
TX VCO
BUFFER
IF Filter
Mixer
Theory of Operation: Main Board
Indicates Sub-shield
*
TX
TX
BUFFER
TX LO
RX
RX SSI Data
Abacus
RX SSI Clock
RX SSI Frame Sync
2nd
LO
FGU
Transmitter
Receiver