Transceiver Board; Figure 3-2. Transceiver (Vhf) Block Diagram (Power And Control Omitted) - Motorola APX 5000 Service Manual

Theory of Operation: Transceiver Board
3.1

Transceiver Board

The transceiver (XCVR) board performs the transmitter and receiver functions necessary to translate
between voice and data from the VOCON board and the modulated radio-frequency (RF) carrier at
the antenna. The transceiver board contains all the radio's RF circuits for the following major
components:
• Receiver
• Transmitter
• Frequency Generation Unit (FGU)
Figure 3-2 illustrates the VHF transceiver board block diagram,
the UHF1, UHF2 and 7/800 transceiver block diagrams.
GPS

Figure 3-2. Transceiver (VHF) Block Diagram (Power and Control Omitted)

Log
Amp
SP3T Rf Switch
Digital
RF Atten
SP3T
Atten
coupler
Rev
Power
Detector
*
÷ 2
16.8MHz
TRIDENT IC
LOGIC PRESCALAR
EXPANDER
BUFFER
16.8MHz
BUFFER
VHF LNA
Figure 3-3
FET
VHF
Driver
Amplifier
Harmonic
Filter
LOOP
VHF TX
FILTER
VHF RX
PRE
BUFFER
RX LO
Mixer
and Figure 3-4
FGU
Transmitter
Receiver
Indicates Sub-shield
*
TX
VHF TX
BUFFER
TX LO
RX SSI Data
Abacus RX SSI Clock
RX SSI Frame Sync
2nd
LO
3-3
illustrates