[Elecraft] Help. K2 noise level variation with band selected

[Ray Collins]

I have noticed that as I change frequency bands on my K2 in SSB mode, the audio noise level changes in frequency content.  On the five lower bands (3.5 to 18.2 MHz), the noise sounds typical for a 2.2 KHz audio bandwidth but on the three higher bands (21.0 to 28.8 MHz) it is predominantly high frequency with greatly reduced low frequency content.

The appropriate sideband is correctly selected for each band, receiver sensitivity appears to be well within specification on all bands and the set works perfectly in all other respects.  Could the band pass filters for the top three bands require adjustment?  If anyone can explain why this is happening and suggest a fix (if one is actually necessary), it would be greatly appreciated


Thanks for your help,

Ray