Hehe, I've been doing this recently. Probably because of poor signal processing in the early stage. In addition, a stable power supply is needed at high frequency, so decoupling is very important. There is also the connection of the circuit. Look at the relevant counters of Wuhan University and Huake on the Internet. They did a good job. I designed it according to their principles, and there is no problem over 20M. Finally, let's go back to your circuit. Is it because the circuit board is not soldered properly and the resistor and capacitor are not selected properly ~ ~ ~ Without your schematic diagram, I can only talk nonsense, hoping to help you.