Two high power coupled-cavity traveling-wave tubes, developed for communications systems are described. These tubes produce 3 kW to 6 kW of saturated output power and 45 dB of gain with very low signal distortion required for multicarrier operation. Small signal gain variations of less than 0.35 dB over a 40 MHz bandwidth and less than 0.8 dB over the entire 7.9 to 8.4 GHz military communications band have been demonstrated. Phase linearity is within

deviation over a 40 MHz band.