A new dual-frequency receiver has been installed on antenna 4 at the end of August. It covers the 80--115 GHz and 210--250 GHz bands, and both mixers can be used simultaneously. The 3mm mixer allows true LSB tuning at all frequencies with high image sideband rejection, and good USB tuning (although with low rejection) at 115 GHz. Measured system temperatures are indicated below:
These measurements were obtained in rather poor weather conditions.
Column 5 indicates typical 
measured with the other antennas
at the same time. Sensitivity has been improved by a factor 2 above
110 GHz. However, as expected, pure DSB tuning is not only less
sensitive, but also very difficult to achieve above
about 100 GHz. Observers are requested to consider seriously this
problem in their applications.
Because of poor weather conditions, only a crude check of the pointing of the 230 GHz receiver has been made so far.
Unfortunately, problems with cryogenics have delayed the other 3 receivers, and no fixed schedule can be given yet.