[Elecraft] K3 S9 calibration?

[Phil & Debbie Salas]

I see in the Yahoo K3 User's Group that Bob Sherwood just discussed filter 
performance with the K3 he has been testing.  He commented that S9 at 50uV 
is with the preamp off.  According to my manual, you should cal S9 at 50uV 
with the preamp on.  I cal'd as stated in the manual, but I wonder if this 
is really the right way to do this.  Comments?

Phil - AD5X