Yes it is, utilizing a technique called 'slope detection' - basically listening on a frequency not quite right on, but 1 or 2 kc away. Not very effective, as you've discovered.
The specs on the various public service and civ air bands are quite straightforward - basically, VHF Lo (30-50 Mhz), High (150-174 mhz) and UHF-UHF T (470-512 Mhz) are all FM. Hams have other modes in addition to FM, available for use, found in the 144-148 and 420-450 Mhz bands. Some military stuff resides in the 148-150 mhz range, but for the most part, FM is the rule - though there are some Air National Guard units that I understand use it in AM mode.
Civil Air VHF (108-137 mhz) is basically all AM; a digital mode called ACARS is also found in this band (easily decodeable with the right software and a good shielded connection to a soundcard).
228-400 Mhz is almost all AM; as you've no doubt discovered by now, there are several FM trunking systems in the 380-400 Mhz range, but the 82 cannot listen in nor follow them.
138-144 mhz is used a great deal by Air National guard and National Guard units, with some exceptions (such as the Blue Angels which have used 2 or 3 frequencies in Narrow FM in this band) is basically AM.
That's just a qucik rundown, probably all you need for the 82, which I don't believe has the capability to change the mode of reception regardless of what band you happen to be hearing. 73s Mike
