Motorola APX 1000 Basic Service Manual page 170

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3-6
3.2.2.1 VHF
Once a VHF frequency for transmit has been selected, the Trident IC and the accompanying logic
circuitry will enable the voltage controlled oscillator which then generates the desired transmit
frequency. This transmit signal is then routed to the TX buffer amplifier which amplifies the signal.
The signal is routed to the VHF Driver amplifier and then to the discrete final power amplifier. The
signal now goes through the antenna switch which routes the power to the harmonic filter which will
filter out the harmonics of the carrier signal and then passes through a directional coupler. The
current detection circuit will be Monitored the current drain of driver amplifier and final power
amplifier and feedback to ALC circuitry to adjusts the control voltages to the driver amplifier and final
power amplifier. Finally, the RF signal is routed to the main antenna.
3.2.2.2 UHF1/UHF2 Transmit
Once a UHF frequency for transmit has been selected, the Trident IC and the accompanying logic
circuitry will enable the voltage controlled oscillator which then generates the desired transmit
frequency. This transmit signal is then routed to the TX buffer amplifier which amplifies the signal.
The signal is routed to the UHF1 Driver amplifier and then to the discrete final power amplifier. The
signal now goes through the antenna switch which routes the power to the harmonic filter which will
filter out the harmonics of the carrier signal and then passes through a directional coupler. The
current detection circuit will be Monitored the current drain of driver amplifier and final power
amplifier and feedback to ALC circuitry to adjusts the control voltages to the driver amplifier and final
power amplifier. Finally, the RF signal is routed to the main antenna.
3.2.2.3 700/800 MHz Transmit
Once a 700/800 MHz frequency for transmit has been selected, the Trident IC and accompanying
logic circuitry enable the correct voltage controlled oscillator which then generates the desired
transmit frequency. This transmit signal is then routed to the TX buffer amplifier which amplifies the
signal. The signal is routed to the 7800 Driver amplifier and then to the discrete final power amplifier.
The signal now goes through the antenna switch which routes the power to the harmonic filter which
will filter out the harmonics of the carrier signal and then passes through a directional coupler. The
current detection circuit will be Monitored the current drain of driver amplifier and final power
amplifier and feedback to ALC circuitry to adjusts the control voltages to the driver amplifier and final
power amplifier. Finally, the RF signal is routed to the main antenna.
Basic Theory of Operation: Analog Mode of Operation

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