AR 10046249, Руководство по эксплуатации и обслуживанию, Страница: 43 / 58

Model 150/150AW1000
Rev C 23
3.4 A4 DRIVER AMP
The A2 Driver amp consists of RF matching circuits, an RF transistor a DC current control circuit, a DC
switching circuit and a fault detection circuit. The RF input is fed to a 4:1 transformer composed of T1, T2, and
T3. The push-pull output signal of the 4:1 transformer is connected to the gates of push-pull connected Q1. The
drains of Q1 are connected to a 4:1 transformer composed of T4, T4 and T6. The RF transistor, Q1, has
approximately 24.1 VDC applied to the drains at 2.4 amps current for the driver and 4.8 amps total current
draw. The RF stage has approximately 14dB of gain.
Voltage comparator U1 senses the presence of the –8 VDC. The output of U1 is high if the –8V supply is –5.5
or less. The output of U1 pulls low when the –8 volts is present turning on Mosfet Q2 which supplies the DC
voltages to the drain of Q1.
The current through Q1 is monitored by U2. The output of U2 is fed to an op amp (U5) which has a reference
voltage on the non-inverting input and it compares the output of U2 to the reference voltage and generates an
error signal to vary the gate voltage of the RF transistor Q1 which controls the drain current.
U3 is a positive 5V regulator. It supplies DC to the current sense circuit, U2, the op amp, U5, and the fault
detection circuit, U6. SW1 is a thermal switch. It closes at a heat sink temperature of approximately 70
˚
to
protect the module in the event of an over-temperature condition.
3.4.1 A5 Two-Way Splitter
The Two-Way splitter splits the input signal into two equal-amplitude, equal-phase signals. The amplitude of
each signal is 3–3.5 dB below the input signal when both outputs are termi nated into 50Ω loads .
3.3.3 A6, A7 W-Final Module
A6 and A7 W-Final Amps consists of RF matching circuits, an RF transistor a DC current control circuit, a DC
switching circuit and a fault detection circuit.
The RF input is fed to a 4:1 transformer composed of T1, T2, and T3. The push-pull output signal of the 4:1
transformer is connected to the gates of push-pull connected Q1. The drains of Q1 are connected to a 4:1
transformer composed of T4, T4 and T6. The RF transistor Q1, has approximately 22.5 VDC applied to the
drains at 4 amps current for the driver and 7 amps current for the finals. The RF stage has approximately 18 dB
of gain for the finals and an output compression point of 50 watts or greater from final amplifiers A6 and A7.
Voltage comparator U1 senses the presence of the –8 VDC. The output of U1 is high if the –8V supply is –5.5
or less. The output of U1 pulls low when the –8 volts is present turning on Mosfet Q2 which suppliesthe DC
voltages to the drain of Q1.
The current through Q1 is monitored by U2. The output of U2 is fed to an op amp (U5) which has a reference
voltage on the non-inverting input and it compares the output of U2 to the reference voltage and generates an
error signal to vary the gate voltage of the RF transistor Q1 which controls the drain current.
U3 is a positive 5V regulator. It supplies DC to the current sense circuit, U2, the op amp, U5, and the fault
detection circuit, U6. SW1 is a thermal switch. It closes at a heat sink temperature of approximately 70
˚
to
protect the module in the event of an over-temperature condition.