AR 10044005, Руководство по эксплуатации и обслуживанию

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Rev B 39
3. THEORY OF OPERATION
3.1 GENERAL
The Model 5000A225A 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
Low voltage: Refer to Interconnect Diagram 10044006, Driver Schematic 10044184 and the schematics
referred to below.
High voltage: refer to Interconnect Diagram 10044007, Driver Schematic 10044184 and the schematics
referred to below.
3.2.1 Amplifier RF Input
The RF Input connector is a Type N female which can be located on the front or rear panel of the amplifier
depending on configuration selected.
3.2.2 A1 2W Pre-Amplifier Assembly (Schematic No. 10041189,
10041352, 10041054)
The 2W Pre-Amplifier Assembly consists of 3 sub-assemblies: the A1 Pre-Amplifier Assembly, the A2
Switch Assembly, and the A3 2W Amplifier Assembly.
3.2.2.1 A1 Pre-Amplifier Assembly (Schematic 10041189)
The Pre-Amplifier PWB Assembly consists of a variable attenuator circuit (Q1-Q4), a gain stage (U4), a
resistive splitter (R13, R14, R16), an RF power detector (U6), and associated control circuitry. The overall
gain of the pre-amplifier assembly is approximately 6-8 dB at minimum attenuation. The power detector (U6)
is used to sense the input RF power and it increases the attenuation of the variable attenuator circuit if an
input overdrive condition is detected.
3.2.2.2 A2 Switch Assembly (Schematic 10041352)
The Switch Assembly is made up of a variable attenuator circuit (Q1-Q4) and associated control circuitry.
The switch can either be in an on or off state depending on the Inhibit input signal (E4). In the off state, when
E4 is pulled low, the switch will reduce the amplifier gain by approximately 40 dB.
3.2.2.3 A3 2W Amplifier Assembly (Schematic 10041054)
The 2W Amplifier Assembly has two gain stages (U1 and Q1) that have a combined gain of approximately 30
dB. The output RF power is greater than 2W at the 1 dB compression point.