AR 10046246, Operating And Service Manual

Page: 17 / 46

Rev B 1
1. GENERAL INFORMATION
1.1 GENERAL DESCRIPTION
The Model 125A250 is a self-contained, broadband solid-state amplifier designed for laboratory applications
where instantaneous bandwidth, high gain, and moderate power output are required. A GAIN control, which
is conveniently located on the unit’s front panel, can be used to decrease the amplifier’s gain by 25 decibels
(dB) or more. Solid state technology is used exclusively to offer significant advantages in reliability and cost.
A Model 125A250, used with a frequency-swept signal source, will provide 125 watts of swept power output
from .01–250 megahertz (MHz). Typical applications include antenna and component testing, wattmeter
calibration, and electromagnetic interference (EMI) susceptibility testing, as well as usage as a driver for
frequency multipliers and high-power amplifiers. The Model 125A250 can be operated locally by using the
unit’s front panel controls, or remotely by using the unit’s IEEE-488, RS-232 interface, USB, or Ethernet
interface.
Special features incorporated into the Model 125A250 include the following:
• A Control Panel that allows both local and remote (via a computer interface) control of the amplifier
(including adjustment of the amplifier’s RF Gain during CW mode operation) and provides graphical
displays of the amplifier’s Forward and Reflected power levels.
•
A General Purpose Interface Bus (GPIB)/IEEE-488.2 interface for remote control of the amplifier’s
operating functions.
•
RS232 serial communications including both wire and fiber-optic ports for remote control.
•
USB Communication port
for remote control.
• Ethernet Communication port for remote control.
•
Protection is provided by DC current limiting, over-temperature shut down and RF power limiting.
1.2 SPECIFICATIONS
Refer to the AR RF/Microwave Instrumentation Data Sheet at the end of this section for detailed
specifications.
1.3 POWER SUPPLIES
The Model 125A250 contains two switching power supply. The input voltage range to the power supply is
100–240 VAC, 50/60Hz, selected automatically. The AC input power is approximately 500 watts.
PS1 has a +5 volt, standby supply for the A4 Control/Fault board and the A5 Interface board used for the
remote interfaces.
PS1 is a multiple output supply. The main +15V, 10A supplies voltage to the A1 preamplifier and the A10
Voltage Regulator board. The –15 volts DC is supplied to the A1 preamplifier.
PS2 is a single output supply which pr34.0VDC to the RF final stage and to the A10 Voltage
Regulator board. Primary AC circuit protection is provided by the circuit breaker in the Power Entry Module.