After installation of the new SIS mixer in the G2 receiver at the 30m telescope with improved receiver noise and sideband rejection in the 205-250 GHz band, many observing requests were made to observe outside the nominal frequency range. The frequency limitation had been partly imposed by the horn integrated with the mixer. We present in figure 5 the status of the G2 receiver both with the old horn in February 1994, and after the change of horn in January 1995. The receiver noise is measured with the reference plane in front of receiver.
Alexandre KARPOV, Jacques BLONDEL