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dxAce · March 3rd 08, 09:28 PM posted to rec.radio.shortwave

wrote:

msushi wrote in another thread:
"Noise is measured in volts per root Hz. To get the noise over a
bandwidth, you multiply by the square root of the bandwidth. So using
a 10% narrower filter reduces the noise by 4.8%. So narrowing the
bandwidth helps, but it is not a cure".

Indeed, it is not a cure. Narrowing the bandwidth of a filter also
narrows the audio response, so the narrower the filter is the poorer
will be the audio response and the more difficult it becomes to render
a rare faint DX signal readable. It is vital to my MW DXing of AM
stations that I get as fuller sound as possible. These signals are
very faint and often severely garbled by atmospherics. At best it is a
great challenge to read and identify these signals with enough
information to request and get a QSL. The fullest possible sound is
necessary to clearly hear all the speech harmonics and sibilants, so
as a result I usually DX in ECSS USB mode, but use a comparatively
wide 3.0 Khz filter setting on my Icom IC-756PROIII.

My favourite filter in the R7 is the 3 kHz.

I just wonder why you'd limit yourself to DX'ing in USB mode. Wouldn't you want
to shift sidebands depending upon the interference?