AR 1000W1000G, Руководство по эксплуатации и обслуживанию, Страница: 49 / 70

Rev A 29
3. THEORY OF OPERATION
3.1 INTRODUCTION
The Model 1000W1000G RF amplifier consists of a Pre-Amplifier and a driver amplifier, a 2-Way Splitter,
two 8-Way Splitters, 16 Final Modules, a 16-way combiner, a directional coupler, and a detector assembly.
The driver amplifier section amplifies low level RF signals and provides RF signals that are matched in
amplitude and phase to the 16 Final modules. The 16 output signals combined in the final 16-way combiner,
yield a combined power of 1000 watts or more. Global fault monitoring and reporting is controlled through
the front panel display.
3.2 RF AMPLIFIER OPERATION (SCHEMATIC 10046373)
3.2.1 A1 Variable Gain Amplifier (Schematics 10033907, 10031968,
10035521)
The A1 variable gain amplifier consists of 3 subassemblies: the A1 Pre-Amplifier PWB Assembly, the A2
High Isolation Switch Assembly, and the A3 Two-Watt Amplifier Assembly.
3.2.1.1 A1 Pre-Amplifier PWB Assembly (Schematic 10033907)
The Pre-Amplifier PWB Assembly consists of a stage of gain (U1), a variable attenuator (U2), a resistive
splitter (R3, R5, R4), another stage of gain (U3) an RF power detector (U9) and control circuitry. The overall
gain of the pre-amplifier assembly is approximately 17 dB at minimum attenuation. The power detector (U9)
is used to sense the input RF power and it increases the attenuation of U2 if an input overdrive condition is
detected.
3.2.1.2 A2 High Isolation Switch (Schematic 10031968)
The High Isolation switch is normally in the thru mode. The switch can reduce the amplifier gain by more
than 40 dB when the pulse input (E4) is pulled low.
3.2.1.3 A3 Two-Watt Amplifier (Schematic 10035521)
The Two-Watt Amplifier has a gain of approximately 16 to 18 dB. The Two-Watt Amplifier increases the
overall variable gain amplifier to approximately 31 to 32 dB of gain. The output RF power is approximately
30 dBm at the 1 dB compression point.