I've been running FT8 on my IC-718 at 100W but keep getting reports that my signal is 'wide' from other ops. The PSK Reporter shows my signal spreading well beyond the standard FT8 bandwidth, and I suspect I'm overdriving the PA causing IMD issues. I've heard that keeping power below 50W helps maintain linearity, but I'm not sure about the proper interface level settings.

What's the best practice for setting drive levels? Should I be monitoring IMD values, and what's considered acceptable for FT8 decoding?

You have two control points: the Windows sound level slider (set to 100%) and the WSJT-X Pwr slider for fine adjustment. FT8 can tolerate around -20 dB IMD in good conditions, but cleaner is always better.

I had similar issues with my FT-817 - kept it under 2W and signal quality improved dramatically. The key is staying out of ALC activation - watch your radio's ALC meter during transmission.

FlDigi actually displays live IMD readings which gives instant feedback on signal cleanliness. For contests where every decode counts, I never exceed -25 dB IMD even if it means running lower power.