Radiometer at 31 cm wavelength for the RATAN-600 radio telescope.

A radiometer with FET amplifiers for continuum observations at 31 cm wavelength has been developed and is in daily routine use at RATAN-600 radio telescope. The Stokes parameters either I or U, Q can be measured. A single-beam mode of operation with a noise pilot-signal and gain modulation is used for total intensity observations. There is no individual modulator in the radiometer, the gain is modulated by the changing of the power supply voltage of the amplifier. The bandwidth of the radiometer is 120 MHz, the system noise temperature is 90K, the noise temperature of the front-end FET amplifier is 55K. A modulation method has been used for the polarization measurements. Other features of the radiometer design are described.