[1000mp] Different frequency response in USB and LSB

[Pete Smith]

I just focused on something that I think has been happening with my Mk 5 
since it was a pup.  Listening with the stock 2.4 KHz filter, and no 
antenna on the radio, the background hiss/noise is a noticeably different 
pitch on LSB than on USB.  That says to me that the suppressed carrier 
frequency is offset from the filter passband by a different amount in the 
two modes.  This observation is supported by viewing a waterfall display in 
mmtty; I can see that one sideband has far more rolloff than the other at 
higher frequencies, within the filter passband.

The radio now has the Inrad roofing filter in place; as I say, I *think* 
the pitch difference was apparent before I installed it, but one person has 
suggested that the roofing filter's center frequency and/or passband shape 
may be responsible.  I suppose I can temporarily remove it and see, or is 
there an easier way?


73, Pete N4ZR