Marty,

WSJT will log your contacts to the file wsjtx_log in you Log File.

Whatever mode you are using at the time will go into that file whether
it's FT8 or FT4, etc. If you want to keep them separate, you'll need to
rename wsjtx_log to wsjtx_log_FT8 or wsjtx_log_FT4 as appropriate.
Or, it could be wsjtx_log_FD2020, etc.

Remember, when you switch modes, you'll need to rename those files
back to wsjtx_log as required. You can rename those files whatever you
want, but keep in mind that the wsjtx_log will be the file that gets logged
to as you are operating.

If you ever want to have them all combined with all the modes and events
into one giant wsjt_log (maybe as wsjtx_log_jumbo), you can append
them all together using a text editor such as Notepad in Windows.

GL/73, Bob K8BL