AR 150A400, Руководство пользователя

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Model 150A400 Manual Text
3-1
REV B
SECTION III
THEORY OF OPERATION
3.1 INTRODUCTION
The Model 150A400 amplifier consists essentially of 2 push-pull output stages of broadband MOSFET transistors
driven by a driver amplifier. Overall power gain of the amplifier is a minimum of +52dB for 1 milliwatt input.
Input and output impedance matching circuits are utilized to provide optimum power transfer of the RF signal when
the amplifier is connected to source and load impedance of 50 ohms. Combined with negative feedback at each
stage and factory aligned equalizers, this provides an overall flat frequency response.
The self contained power supply consists of four switching power supplies. Two of the supplies are connected in
series to provide 33 volts for the final amplifier. The third supply provides 28 volts for the driver amplifier. The
fourth supply is used to supplies
±
12VDC and +5VDC to power the operate/control and the gain control. The
four power supplies operate at line voltages of 90 to 132 VAC and 180 to 264 VAC, 50/60 Hz selected
automatically.
3.2 DRIVER AMPLIFIER SECTION
Refer to
"Schematic Diagram Number 1010760, Driver Assy" .
The input signal is fed through the gain control assy to the gate of Q1. Gate bias for Q1 is supplied through R5 and
adjusted by R4. The output of Q1 is coupled through C9 to the equalizing network R8, R9, R10, L5 and C11. The
output of the equalizing network is coupled through C12 to the gate of Q2. Gate bias for Q2 is supplied through
R12 and adjusted by R11.
The output of Q2 is coupled through transformers T1 and T4, which drives the push-pull stage Q4A and Q4B.
Resistor R20 is used to adjust the bias voltage for both Q4A and Q4B, in conjunction with R21 which is used to
balance the push-pull operation. The output of Q4A and Q4B are coupled through matching transformer T2 and
balun T3 to a coaxial connector, which is the driver's output.
3.3 TWO WAY SPLITTER
Refer to Schematic Diagram Number 1011336 Two Way Splitter
The output of the driver is fed to the two way splitter where the signal is evenly distributed to the two (separate)
Basic Power Modules.
3.4 FINAL AMPLIFIER SECTION
Refer to
"Schematic Diagram Number 1011290, Basic Power Module (“A”)" .
The following description applies to 1 section. The same description applies to the second Basic Power Module
“B”.
The input signal is applied to coax connector P2. The signal is then conducted to transformers T1 and T2 which
provide impedance matching to the push pull transistors Q1A and Q1B. The bias voltages are adjusted by R22 and
R23.