[en] In order to improve the noise immunity and increase the availability of the DIII-D ECE radiometer, the radiometer receiver will be located outside the radiation shield wall. Further noise immunity is obtained by the use of a 50 kHz rf modulator, which is compatible with the 90 to 140 GHz low loss, single mode transmission system, the design and expected performance of which will be discussed. The testing of microwave components and the absolute calibration of the system is also discussed