Amplifier Research 75A250A

The Amplifier Research 75A250A is a solid-state RF amplifier delivering 75 watts CW minimum across 10 kHz to 250 MHz with instantaneous bandwidth operation. Built on push-pull MOSFET circuitry, it achieves 45 dB typical gain with ±1 dB flatness and operates unconditionally into any load impedance without damage or oscillation. The unit accepts modulated input signals

AM, FM, or pulse - and reproduces them faithfully at the output.

Front panel RF gain control and remote operation via IEEE-488 GPIB or RS-232 enable flexible laboratory integration. Over-temperature and input overdrive protection safeguard against faults, while a digital display reports operational status and fault conditions in real time.

Technical Specifications

• Frequency Range: 10 kHz to 250 MHz instantaneous bandwidth


• Output Power: 75 W CW minimum; 100 W CW nominal; 50 W linear at 1 dB compression (46.99 dBm P1dB)


• Gain: 45 dB typical; 49 dB minimum at maximum setting; 18 dB continuous adjustment range


• Gain Flatness: ±1 dB typical and maximum


• Input/Output Impedance: 50 Ω; input VSWR 1.5:1 maximum; output VSWR 2.0:1 maximum


• Input Power for Rated Output: 1.0 mW maximum


• Noise Figure: 6 dB typical (above 1.0 MHz)


• Harmonics: 20 dBc


• IP3: 57 dBm / 501.19 W


• AC Power: Universal autoranging 90–135 VAC or 180–270 VAC; 47–63 Hz; 400 W nominal consumption


• Connectors: N-type female input; N-type output


• Cooling: Air-cooled with built-in fan


• Dimensions: 50.3 × 15.5 × 37.6 cm; 20.5 kg

Key Features

• Load-mismatch tolerant: 100% rated power operation with any impedance


• Diode limiter input overdrive protection


• Over-temperature shutdown with automatic fault reset


• Remote control via GPIB and RS-232 asynchronous full-duplex serial


• Built-in AC circuit breaker protection

Typical Applications

• RF susceptibility testing


• Antenna and component characterization


• Watt-meter calibration


• Driver stage for higher-power amplifiers and frequency multipliers

Compatibility & Integration IEEE-488 GPIB and RS-232 enable integration into automated test systems. The amplifier reproduces AM, FM, and pulse modulation on input signals without distortion, supporting complex signal conditioning in laboratory environments.