We propose to build an electrostatically focused klystron that exploits recent breakthroughs in scandate cathode technology. We have built cathodes with greater than 100 Amps/cm2 emission. This project offers an opportunity to test those cathodes in real world devices. Because of their small size (.050 inch diameter) and low power dissipation (under 1.2 watts), they are ideal for long-range space missions. Also, their low beam convergence makes electrostatic focusing feasible. This, in turn, provides a dramatic reduction in amplifier size and mass. Without magnets, traveling wave tubes and klystrons will be lighter and smaller, a further enhancement for space missions. Phase I develops cathodes, pierce guns and focusing stacks. Phase II will see construction of a working klystron or TWT. Scandate cathodes also provide longer life than conventional cathodes. Their small size allows amplifiers to reach much higher frequencies, bandwidth, and data rates than current art.