I don't know how the makers do their adjustments, but i guess they take a radio have a set menu values and some measuring equipment and adjust each setting per transceiver till it fits the specifications.
And not too much time to spend....
Strange thing is this AM modulation fault was noted to Yaesu in 2015 with the 991 so you would expect them to adjust their factory settings, but no, as said mine was made in March this year and still had the same fault.
One would expect the technician adjusting the transceiver to note the distortion in AM, but maybe they don't test that.
I only researched for the solution hence the downloading and careful reading of the technical manual describing the adjustment procedure for each step.
I already used the 100 MHz scope and saw the distortion didn't come from the P.A. but from the driver section.
Then i found the internet story and followed up that taking care noting down the original setting and checking progress on the scope.
Add FT2000-D as control receiver to hear the changes.
I might have used a bit higher setting, but my goal was a clean and crisp audio with absolutely no distortion and have a few watts less out I won't lose sleep over.
As said making more power is easy once it is clean.
