The paper presents an instrumental diagnostic complex developed by the authors. The compact LR1 spectrometer for spectral diagnostics of particle temperature of two-phase flow is an integral part of the complex, as well as the calibration tool with the reference emitter. Additionally, a special emitter consisting of miniature light bulbs attached closely to each other was used in test experiments. This special emitter served as a simulation model of particle thermal radiation of gas-thermal flow used for spraying of functional coatings on technical products. The program-controlled adjustment of current flow through bulbs interconnected in different configurations yields a variety of simulated test histograms of the temperature distribution of the bulbs that correspond to actual particle temperature distribution histograms. The emitter with light bulbs has been used as a simulation model to confirm the validity of the physical and mathematical model of the integral (total) spectrum of particle thermal radiation for the proposed experimental spectrum registration method employing the LR1 spectrometer.