"Paul Sherwin"

In the US and Canada, AM stations are allocated 10kHz bandwidth,
giving a theoretical 5kHz treble cutoff. In most other place that's
9kHz/4.5kHz. Stations transmit a more restricted frequency range than
this though, for a number of technical reasons. That's where my rough
and ready 3.5kHz figure came from.

Best regards, Paul


** In Australia the AM channel spacing goes in 9 kHz increments, however
the transmitted bandwidth is not affected by that fact since the authorities
have kept a wide frequency separation between transmitters serving the same
areas.

The recovered audio from many transmitters is of good quality on speech
and music with high frequencies extending to 12 kHz in some cases - the
government owned networks being the best in this regard. At night, far
distant adjacent channel signals can produce an audible 9 kHz background
whistle which a sharp notch filter deals with most effectively. I use an
Australian made valve AM tuner designed for hi-fi reception of local
broadcasts and have tried out a few SS hi-fi AM designs as well.

The secret of good AM reception is the use of a balanced loop or frame
antenna to reduce man made and static noise to insignificance.



............ Phil