The GA-2500A is a limited-duty cycle amplifier producing high-power RF tone bursts derived from either a continuous-wave (CW) source or an externally generated low-level (~1 Volt peak-to-peak) tone burst. In addition to the RF input, a coherent gate (TTL/CMOS) is required to turn the amplifier on. Two different versions are available depending on the polarity of the coherent gate. The standard GA-2500A uses a positive TTL gate (high during the on time and low during the off time) similar to those produced by the Stanford Research Systems DS-345 function generator. The GA-2500A-NG uses a TTL gate which is high during the off time and low during the on time. This type gate is produced by the Agilent 33120A function generator. The power output is continuously adjustable by a front panel potentiometer. Three versions of the instrument are available with different maximum output levels: 5 KW, 1.5 KW, and 400 W root mean squared (RMS) power into 50 Ohms during the burst. The frequency span of each amplifier is tailored to meet the user’s needs within the range of 40 kHz to 20 MHz.