Adding to the S.M.A.R.T. power amplifier line, the QBS-559 is a 50W, 20 MHz to 800 MHz amp that automatically adjusts its active biasing to boost efficiency under various load mismatch conditions. Its rugged, push-pull design can withstand a 10:1 load mismatch. Delivering 45 dB of linear gain, the 21 to 30 Vdc amp produces 50W using just 5.1A at 28V. It integrates a dc/dc converter and heatsink, and offers a variety of fault and monitoring options. Spectrum Microwave Inc., Philadelphia, PA. (888) 553-7531.