The first observation at RATAN-600 was made with North sector on July 12, 1974. At the wavelength 3,9 сm radiation from the radio source PKS 0521-36 was received. The radiometer was build by team of Pulkovo engineers headed by D.V. Korol'kov , who was appointed to be Deputy Chief Designer of RATAN-600 in electronic equipment ( Chief Designer was N. L. Kaydanovsky at that time ). ... In 2014 RАТАN-600 celebrated its 40 anniversary since the first observation was conducted. ...