[Elecraft] K3 NB Generates noise

[Ed Stallman]

I finished K3 Kit 6644 yesterday and noticed today when using the NB 
on 6m that it the NB will generate noise only on a few different 
levels ! With NB Level on then DSP set to off .. I now turn 
IF-NAR  from off  through the numbers 1 to 7 ...when I get to 
IF-NAR  6 and 7 it is much noisier then 2,3,4, or 5 with 4 being 
best  ! Is this normal ? I was thinking the higher numbers would 
reduce more noise ? Using IF-MID and WID 1 has more noise and 7 is less

Thanks Ed