1, the grounding is not good, so you can increase the grounding area or connect with the shell;

2. The provided DC power supply is not filtered enough, which makes it not clean enough. At this time, it is necessary to increase filtering measures;

3. When the RF signal is coupled to the DC voltage, a magnetic ring can be sleeved on the low-frequency line, and the low-frequency line and the RF line are as far away as possible or change direction;

4. There is a serious mismatch between amplifiers at some frequency points, which leads to the reflection of RF signals back and forth. In this case, it is necessary to readjust the circuit or appropriately increase the isolation between matches.

5, poor heat dissipation, with the increase of temperature, the internal performance of the power amplifier tube becomes worse, causing instability. This situation needs to strengthen heat dissipation.

6. Self-excitation of power amplifier caused by parasitic parameters, such as self-excitation caused by introducing parasitic parameters after covering the whole machine shell. In this case, it is necessary to reconsider the form of input and output circuits to avoid serious distortion of characteristics after introducing parasitic parameters.

I hope the above content can help you.