I have found on my IC7410 and IC7100 that I need one bar showing for full power out. As Bob mentioned it does change with what band I am operating. Seems like the higher frequencies, 20 and above, need less audio input than the lower frequencies, 30 and down. I made a chart of what my audio input setting should be and try to remember to set the audio when I change bands. Since the PSKMeters are hard to find, I use a SDR receiver with Fldigi to check my signal. I saw a Youtube video on how to set up with a scope, but have not done that as of yet.
I also noticed that my FT817ND need at least one bar of ALC or there is no output.
I missed the 80 sprint, as we are working in MD and I don't have an 80mtr antenna for the van.
Dick - KC3EF