Radio frequency signal generators (RF) are instruments used to test reception equipment and RF components like filters, amplifiers, attenuators, among others. On the other hand, they reinforce the teaching-learning processes and they are widely used in research in the telecommunications field. This document provides the first stage of a low-cost signal generator design by using RaspBerry Pi 3, with the documentary exploration about this kind of applications. After that, a recognition of the RaspBerry Pi 3 is done at hardware and software level. Finally, an application of an FM signal generator with RaspBerry in a frequency of 101.3 MHz is evaluated, which does not require any additional hardware. This signal was captured using a spectrum analyzer, which determined good quality of the modulated signal in terms of power, bandwidth and SNR (Signal Noise Ratio). However, there are some unwanted harmonic components