Abstract <p>The technique for calibration of receiving equipment for an experiment on recording spectra of collective Thomson scattering at a frequency of 54.5 GHz in an open magnetic trap is described. This scattering is the basis for ion-distribution function diagnostics, widely used in toroidal traps, tokamaks, and stellarators, and the challenge is to adapt this method to an open trap. The transition to a new type of trap required the use of an original approach to calibration, which solved two problems. Firstly, using the existing equipment, the spectrum of the signal from a thermal source with a temperature of approximately 200 K was recorded with an accuracy of 3%. Secondly, the receiver was matched with the noise generator.</p>