A block diagram of the receiver system is shown in Figure 1. The SMT beam passes through an optical system which converts the beamwaist to a size (1.00 mm) appropriate for entrance into the waveguide mixer. The local oscillator beam is coupled into the telescope's beam using a Mylar beamsplitter. The I.F. bandwidth of the receiver is 0.8 GHz, with a nominal center frequency of 1.4 GHz. A total power/upconverter box is provided with the receiver. The total power box also provides a DC output voltage proportional to the I.F. power level. The 3-4 GHz rf output of the total power box is fed to the facility AOS's. The box also has a 1-2 GHz rf output for real time monitoring of the receiver passband.