Bob,

Here's a site that has a list of U.S. freq allocations. Though a little old
it will give you a pretty
good idea of the modes and tuning steps between freqs. Also the various freq
bands. As others
told you they are all AM mode. The military aviation (MilAir) band is
225-400 Mhz and is almost
always AM mode.

http://aosc.org/alloc.html

Regards,

SparkS