On Wed, 23 Jul 2003 20:09:30 -0500, Robert Grizzard belch-spoke these
words:

Matthew and Wendy Plante wrote:

So, If I had a receiver capable of AM reception, then a CW filter would
work?

Max and Bob both mentioned a beat frequency oscillator. This is
necessary to hear CW on an AM radio. You might beable to loosely couple
an external oscillator to your AM radio and have it beat against the IF.
The oscillator will want to be 800 Hz either higher or lower in
frequency than your last IF.

If you have ever used harmonics to tune a string instrument then you
have heard beat notes in operation. When you pluck the E string on a
guitar while you're touching the string over the fifth fret then pluck
the A string while you're touching it over the seventh, they should both
be vibrating at the same basic frequency. If they're not, you'll hear
the guitar go "woooOOOOWWWWWWOOOOoooowwwwooooOOOOWWWWWWOOOOOOooo oo",

Nice sound effect.

and
the rate at which the "wow"s get louder and softer is the difference in
tuning between the strings. A CW receiver -- or sideband receiver, for
that matter -- does the same thing except at RF instead of at audio
frequencies.

HTH

de kg7yy