This S-band circuit-card power amplifier is developed for SWaP-constrained LEO spacecraft, providing 2.5 W at P1dB and 3.2 W saturated across 2.0 to 2.5 GHz with low DC current draw. A UART interface reports forward output power, current and temperature, and accepts commands for programmable enable and software-set thermal shutdown thresholds. Linear gain is 27 to 28.5 dB and saturated gain 24 to 25.5 dB. Second and third harmonics are held to -60 dBc, and switching is 1 µs from TTL high to RF output. Supply is 4.75 to 5.25 VDC drawing 3.2 A typical and 4.2 A maximum operating, 1.4 A quiescent enabled and 14 mA maximum disabled. Applications include payload downlinks, CubeSat and SmallSat communications, IoT networks and direct-to-device architectures. Interfaces are MMCX-F on RF with an Omnetics control connector, cooled by baseplate conduction. The card is 78 x 33 x 4 mm (3.075 x 1.305 x 0.15 in) at 14 g, rated -40 to +85 °C with 0 to 95% humidity tolerance and vibration to MIL-STD-810. Typical lead time for standard configurations is 8 to 10 weeks.