[Elecraft] K2 Filter Abnormality :Alignment with Spectrogram

[Michael van Hauten]

When doing the filter alignment with spectrogram i see a filtercurve   
going up to -30db for approx 5 seconds. Then the signal goes down to  
-40db. Alway when switching to another band or to another mode this  
happens.  This effect is independent from the operation mode (LSB,  
USB, CW). First the signal goes up to -30db and then down to -40db.  
Switching on or off the AGC does not matter. Increasing AF Gain helps  
not  to get a steady signal at -30db. What causes this effect ? What  
is wrong?
Thanks for help
Michael, DC0ZO