I want to share a sine/square wave oscillator up to 40MHz with 1Hz precision by AD9850 direct digital synthesizer (DDS) module. The module is available in eBay under 7$ and generates around 600mV p-p sine wave with 5V power supply. Attached here is MikroC Pro v6.0 working project code and module datasheet. It can be used in radio tuning operation as a Variable Frequency Oscillator (VFO). The module includes a filter in output stage so it can be used as a nice, clean sine wave oscillator within the range. The program the frequency you have to change the LSB 32-bit of the variable set_freq.
Module datasheet link: http://www.eimodule.com/download/EIM377_AD9850_Signal_Generator_Module_V01.pdf