AR 10036390, Operating And Service Manual

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Rev D 29
3. THEORY OF OPERATION
3.1 GENERAL
The Model 800A3B amplifier can be a relatively simple unit to understand. The amplifier chain is a
straightforward design, with a few control elements in the lineup. The unit’s power supply, control and fault
detection circuits can be easily understood by anyone with a minimal understanding of analog and digital
circuitry.
3.2 AMPLIFIER
Refer to Block Diagram Number 10021828, Interconnect Diagram 10036395, Driver Schematic 10021074
and the schematics referred to below.
3.2.1 Amplifier RF Input
From the RF input, the signal path is as follows. From the Type N connector on the control panel, the signal
travels to the driver, which is a self-contained, RF-tight assembly.
3.2.2 Driver Assembly
The driver assembly has three parts, the variable gain amp, the low level amp, and a 4-way splitter.
3.2.2.1 Variable Gain Amp
Refer to schematic 10020743. The variable gain amplifier is a broadband IC with a voltage-controlled gain
feature. It is powered by ±5VDC.
3.2.2.2 Low-level amplifier
Refer to Schematic 10021074. The next element is the low-level amplifier module, also located in the driver
assembly. This amplifier has approximately 40dB of gain. It is powered by +27VDC. Gain flatness is
adjusted in this assembly.
3.2.2.3 4-Way Splitter
The last element in the driver assembly RF path is a 4-way RF power splitter, which feeds the four output
modules with equal amplitude and phase signals.