  In this paper, we summarize the high power testing results of the X-band
mixed-mode RF windows at KEK and SLAC for linear colliders. The main feature of
these windows is that the combination of modes on the surface of the ceramic
significantly decreases the electric and magnetic fields in the junction
between the ceramic and the metal. So far two types of high power windows (with
the diameter of 53 mm and 64 mm) have been fabricated. A high power model of
the smaller type window was fabricated and tested in a resonant ring at KEK. A
maximum circulating power of 81 MW with 300 ns duration or 66 MW with 700 ns
duration was achieved. Light emission was observed for a power level of over 10
MW. Later, both windows were shipped to SLAC for even higher power testing
using combined power from two klystrons. The first window (53 mm diameter)
achieved a transmitted power of 80 MW with 1.5 microsec duration at 30 Hz
repetition. It was not destroyed during the testing. The testing of the second
window was carried out next to the small type and achieved 62 MW with 1.5
maicrosec duration with 10 Hz repetition. The final results of both windows are
presented in this report.
