Preamp Setting Flex 8400M for FT8

For manually setting the level:

https://helpdesk.flexradio.com/hc/en-us/articles/204923669-How-to-Determine-the-Correct-Amount-of-RF-Preamp-Gain-for-Different-Band-Conditions

Or if you are using SDC, that program sets the AGC-T automatically for you and dynamically updates the level as conditions change. With this aim for a level of 50 and set the preamp accordingly. If you have the preamp not set optimally, SDC will compensate. This is very useful since the usual mistake is to apply too much preamp gain. Take heed of what Tim Ellison writes at the beginning of his article.