Motorola APX 2000 Detailed Service Manual

3-20 Theory of Operation: Main Board
To select the 700 TX VCO, pin E5 (GPO1) must be at a high logic level and pin D5 (GPO2) and pin
D6 (GPO8) must be at a low logic level. The output of the 700 TX VCO is then split into two signals.
One to the Prescaler buffer input and the other to the prebuffer input. The output of the prebuffer is
then fed to pin 1 (RFC) of U738. The output of U738, pin 4 (RF1) then goes to the transmit injection
buffer (comprised of Q774 and surrounding circuitry). The output of the transmit buffer, then goes to
the transmit section via the TX_INJ transmission line.
To select the 700/800 MHz TX VCO, pin D5 (GPO2) must be at a high logic level and pin E5 (GPO1)
and pin D6 (GPO8) must be at a low logic level. The output of the 700/800 MHz TX VCO is then split
into two signals. One to the Prescaler buffer input and the other to the prebuffer input. The output of
the prebuffer is then fed to pin 1 (RFC) of U738. The output of U738, pin 4 (RF1) then goes to the
transmit injection buffer (comprised of Q774 and surrounding circuitry). The output of the transmit
buffer, then goes to the transmit section via the TX_INJ transmission line.
To select the 800 TX VCO, pin D6 (GPO8) must be at a high logic level and pin E5 (GPO1) and pin
D5 (GPO2) must be at a low logic level. The output of the 800 TX VCO is then split into two signals.
One to the Prescaler buffer input and the other to the prebuffer input. The output of the prebuffer is
then fed to pin 1 (RFC) of U738. The output of U738, pin 4 (RF1) then goes to the transmit injection
buffer (comprised of Q774 and surrounding circuitry). The output of the transmit buffer, then goes to
the transmit section via the TX_INJ transmission line.

Motorola APX 2000 Specifications

General

IP Rating	IP67
Operating Temperature	-30°C to +60°C
GPS	Optional
Bluetooth	No
Frequency Range	700/800 MHz
Power Output	1-5 W (VHF), 1-3 W (700/800 MHz)
Channels	Up to 1, 000
Battery Life	Up to 10 hours (digital)
Digital Protocol	APCO P25
Frequency	VHF: 136-174 MHz, UHF: 380-470 MHz, 700/800 MHz: 764-870 MHz
Power	1-3W (700/800 MHz), 1-5W (VHF)