The best SSB TX settings for lowest 3rd Order Intermodulation Distortion and meet Part 95 (-25db within 8khz of the fundamental frequency) from my experimentation are as follows:
MIC Gain 20
PROC Level 13
AMC Level 25
SSB TX BPF 200-2800HZ
All other SSB TX settings left at default.
The FTDX10 Service manual specs 3rd Order IMD: -31 dB @ 14mhz 100 Watt PEP.
I’m seeing better than service manual specs with the above settings: -35 dB @ 28mhz 100 Watt PEP. I have only tested the above settings on the 10 meter band. Although, being an SDR, I doubt there would be a significant change from band to band. Again, being an SDR, there also seems to not be much change in PEP across the board with a change in MIC Gain, AMC or PROC setting changes. At least from my testing so far.
I notice in the service manual that there looks to be no specific PA alignment procedure to minimize 3rd Order IMD. I guess that’s not unusual. It seems to be left up to the tech to decide how to best align for low 3rd Order IMD in most radio alignment procedures from all radio manufacturers over the decades. But the FTDX10 being an SDR, it is possible to do it via setting changes, which is great.