I have an interest in sampling AM talk shows over a wide geographic range.
At night, I can pick up many stations east of the Mississippi, and some all
the way to the Rockies.

AM reception is generally plagued with whistles, known as heterodynes, that
are intermodulation products from stations on adjacent frequencies. Some
communications receivers are equipped with notch filters and/or digital
processing to remove these.

Are there any tuners specifically for the AM "phile", that incorporate these
features. Wide bandwidth is not a must for my purpose, but heterodynes are
very fatiguing. I could purchase a modern communications receiver, but these
are expensive.