AR 10046249, Operating And Service Manual, Page: 41 / 58

Rev C 21
3. THEORY OF OPERATION
3.1 INTRODUCTION
The Model 150/150AW1000 RF amplifier consists of a 0.01–100 MHz RF amplifier assembly and a 80 to 1000
MHz amplifier assembly.
The power supply section consists of an AC input filter, a switch, three switching power supplies, and a
regulator circuit.
The control system consists of a Control/Fault Board, an Interface Board and remote interfaces for IEEE-488,
RS-232, USB, and Ethernet.
3.2 RF AMPLIFIER OPERATION - 0.01-100 MHZ (Schematic 10046147)
The RF amplifier assembly consists of a Pre-Amplifier (Pre-Amp), and a 150 Watt, 100 MHz module.
3.2.1 A1 2W Pre-Amplifier Assembly (Schematic 10041189,
10041352, 10041055)
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.
3.2.1.1 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.
3.2.1.2 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.
3.2.1.3 A3 2W Amplifier Assembly (Schematic 10041055)
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.