[Elecraft] Wider bandwidth while listening to AM SW on the KX3?

[Alan Bloom]

On 11/01/2013 05:02 PM, George Danner wrote:
> Guys,
> AM Broadcasting isn't your grandmother's AM radio of old.
> Many years ago, along came NRSC and it's 10kHz brick-wall filter

FCC regulations [73.44 (b)] for AM broadcast stations require the 
emissions to be at least 25 dB down from the un-modulated carrier at 
frequencies greater than 10.2 kHz from the carrier.  Back in the days of 
analog filters it was difficult to get much more than 5 kHz bandwidth 
and still guarantee at least -25 dB at 10.2 kHz.  Now with digital 
filtering you can get out to almost 10 kHz and still meet the spec.

For comparison, the audio bandwidth of FM stations is 15 kHz and the 
audio tends to have much less distortion (which is generated mainly in 
the receiver's AM detector).

Since AM stations in the US are spaced 10 kHz apart, a station whose 
modulation extends +/- 10 kHz from the carrier will heavily interfere 
with the channels above and below it.  Supposedly the FCC assigns 
channels in such a way that stations in the same area are not adjacent, 
in order to reduce interference.  But of course that does not work at 
night due to long-distance skip propagation.

Alan N1AL