Hello. I've create a VFO board using AD9850 module (PCB including 125 MHz crystal ... ). It works. My working frequency is around 20 MHz. But ... I've noticed a small jitter, mainly in frequency. With my scope I've discovered a low frequency (between 300 and 1500 Hz according to the board in test) with same amplitude that HF signal, about 400 mV p-p which appears on same output. Has someone an idea about this default and how to suppress this modulation ?