Calibrate FWR meter

[F1SSF]

Hi alls,
I have a small problem adjustment, I explain ..
Config > PWRsdr mRX + HERMES board + Hercules PA 100W.

I have different power output between wattmeter PWsdr, Hercule wattmeter . (2w to 12w differences. for low power and hight power)
I don't understand, because FWR is delivered by CAN in PA, and communicate directly with PA display and HERMES input, and the read values are not same.

Is someone can help me?? Peharps my PWRsdr is not correctly configured ( I have choose ALEX option), are there offset ??

Thank you, 73 Franck F1SSF