HARRIS CORPORATION TR-390-A2 Manual Do Utilizador
2-2 Pre-Driver
The output of TR101 is applied to the Pre-Driver IC101 through an attenuator pad R106-R108. The output of
R107 is also amplified to about 600mW by IC101. This is controlled by TXENB+. The Pre-Driver consists of
three stages RF amplifier. The first and second stages in IC101 are operated in Class-B. The third stage in
IC101 is operated in Class-C.
The output of TR101 is applied to the Pre-Driver IC101 through an attenuator pad R106-R108. The output of
R107 is also amplified to about 600mW by IC101. This is controlled by TXENB+. The Pre-Driver consists of
three stages RF amplifier. The first and second stages in IC101 are operated in Class-B. The third stage in
IC101 is operated in Class-C.
2-3 PA Module
The output of IC101 is applied to the PA Module IC102 through an attenuator pad R110-R112. The output of
R110 is amplified to about 13W. The PA Module consists of three stages RF amplifier. The first stage power
supply voltage is controlled by power control circuit. The second and third stage power supply voltages are
supplied by B_A+ via TR108. The first and second RF amplifiers are operated in Class-B. The third RF
amplifier is operated in Class-C.
The output of IC101 is applied to the PA Module IC102 through an attenuator pad R110-R112. The output of
R110 is amplified to about 13W. The PA Module consists of three stages RF amplifier. The first stage power
supply voltage is controlled by power control circuit. The second and third stage power supply voltages are
supplied by B_A+ via TR108. The first and second RF amplifiers are operated in Class-B. The third RF
amplifier is operated in Class-C.
2-4 RF Amplifier
The input (about 13W) of the RF Amplifier is amplified to 25W.
Power Supply voltage for the RF Amplifier is connected with POWER SUPPLY BOARD through C1.
2-4 Automatic Power Control
The Automatic Power Control circuit samples the output power to the antenna to maintain a constant power
level across the band. Also, a thermistor circuit (TR104 and RT101) senses the PA Module temperature to
reduce the power level when the temperature is above +110
The input (about 13W) of the RF Amplifier is amplified to 25W.
Power Supply voltage for the RF Amplifier is connected with POWER SUPPLY BOARD through C1.
2-4 Automatic Power Control
The Automatic Power Control circuit samples the output power to the antenna to maintain a constant power
level across the band. Also, a thermistor circuit (TR104 and RT101) senses the PA Module temperature to
reduce the power level when the temperature is above +110
°
C. The Automatic Power Control circuit controls
the supply voltage to the first stage in PA Module IC102. Directional coupler provides a sample of transmit
power for diode CD102. Diode CD102 produce a positive DC voltage proportional to the transmit circuit
output power level. When above VSWR 3, reflect coupler provides a sample of reflection power for diode
CD101. Diode CD101 and CD102 produce voltages are summed, then that is compared to APCREF (D/A
Voltage) from SYSTEM CONTROL UNIT by the amplifier TR105. The collector of TR105 is applied to DC
amplifier TR106 and TR107, then the output voltage of TR107 controls to the first stage of PA Module.
power for diode CD102. Diode CD102 produce a positive DC voltage proportional to the transmit circuit
output power level. When above VSWR 3, reflect coupler provides a sample of reflection power for diode
CD101. Diode CD101 and CD102 produce voltages are summed, then that is compared to APCREF (D/A
Voltage) from SYSTEM CONTROL UNIT by the amplifier TR105. The collector of TR105 is applied to DC
amplifier TR106 and TR107, then the output voltage of TR107 controls to the first stage of PA Module.
2-5 Antenna Switch and Low Pass Filter
The Antenna Switch consists of CD103, CD105-CD107, CD109 and the Low Pass Filter consists of micro
strip line and C146-C153,C181 and C183.
During transmit, TXENB+ line from SYSTEM CONTROL UNIT is high level. Transistor TR109 turns on
supply +9VT to the Class-A Amplifier and Pre-Driver, Automatic Power Control circuit and PIN diode
Antenna Switch CD103, CD105-CD107 and CD109. When transmitting, the Antenna Switch diode is low
impedance.
The Antenna Switch consists of CD103, CD105-CD107, CD109 and the Low Pass Filter consists of micro
strip line and C146-C153,C181 and C183.
During transmit, TXENB+ line from SYSTEM CONTROL UNIT is high level. Transistor TR109 turns on
supply +9VT to the Class-A Amplifier and Pre-Driver, Automatic Power Control circuit and PIN diode
Antenna Switch CD103, CD105-CD107 and CD109. When transmitting, the Antenna Switch diode is low
impedance.
3, Frequency Synthesizer Circuit
The Frequency Synthesizer circuit receives PLL data, and control information from the microcomputer and
from this generates the Tx / Rx RF frequencies.
It also provides frequency lock status to SYSTEM CONTROL UNIT. It consist of the Reference Oscillator,
PLL Frequency Synthesizer chip IC305, Loop filter, Rx VCO TR307, Tx VCO TR304, Feedback Buffer
Amplifier, and Dual-Modulus Prescaler IC306. Rx VCO and Tx VCO are locked to the Reference Oscillator
by a single direct-divide synthesis loop consisting of the Feedback Buffer, Prescaler, and PLL Frequency
Synthesizer chip.
The Tx VCO operates over a frequency range of 403-412.5MHz and 425.5-435MHz.
The Rx VCO operates over a frequency range of 384.4-393.9MHz.
The Frequency Synthesizer circuit receives PLL data, and control information from the microcomputer and
from this generates the Tx / Rx RF frequencies.
It also provides frequency lock status to SYSTEM CONTROL UNIT. It consist of the Reference Oscillator,
PLL Frequency Synthesizer chip IC305, Loop filter, Rx VCO TR307, Tx VCO TR304, Feedback Buffer
Amplifier, and Dual-Modulus Prescaler IC306. Rx VCO and Tx VCO are locked to the Reference Oscillator
by a single direct-divide synthesis loop consisting of the Feedback Buffer, Prescaler, and PLL Frequency
Synthesizer chip.
The Tx VCO operates over a frequency range of 403-412.5MHz and 425.5-435MHz.
The Rx VCO operates over a frequency range of 384.4-393.9MHz.