The postcharge regulator 3A8 is an important part of CINRAD/SA and CINRAD/SB radar, which is used to gain enough ground clutter suppression for the radar system and to regulate the PFN charge voltage within 004 percent of the desired operating point until the PFN is discharged. After the PFN charge voltage being charged to the rated value from the charging transformer, the charges stored in the PFN can be controlled by selectable discharge by sampling the PFN charge voltage. So the cycletocycle variation regulation by the post charge regulator minimizes the phase and amplitude variations in the RF output. The operating principles of Regulator 3A8 are discussed in details, and the analysis is made of the structure of the electronic circuit. Also a number of key point waveforms are discussed with the pulse sequence. Based on the maintenance experiences of the radar system, some simple and effective methods in troubleshooting and maintenance are introduced and summarized with the relevant alarm massages.