[Elecraft] KX3 sensitivity

[w1az at comcast.net]

I've used an XG3 and the audio voltage/db feature in the KX3 to check the sensitivity. In CW mode with the bandwidth set at 2.8kHz I get -131db. With the filter set at 0.05kHz it's -140db. I also tried with the peaking filter turned on and got -148db for both filter widths. Just curious how this relates to the specification of -137db, i.e. what bandwidth was used for that spec? 

Bernie 
W1AZ