In short, the answer is no. To a point, Airtronics is on the same band/frequency as Futaba, Hitec, and all the generics like Traxxas, duratrax, hpi, etc.
The long of it is: the key difference lies mostly in the phase shifting (positive or negative shift) that dictate the differences in the crystals.
As for AM and FM, it's pretty much the same concept behind the AM and FM radios, except on a different band. Lets' take your average car stereo, for example. On the AM band, a typical station is between 600-1100 (I think it's Mhz, and not Khz... but I might be wrong). I don't have a radio in front of me, so I can't say at the moment.
On the FM side of the dial, however, your typical stations are between 87.1 and 107.9 (again, correct me if I'm wrong).
Notice the difference in frequencies, and how AM and FM don't cross paths? Keep that in mind.
However, this is not the case with our model cars, as some people believe. AM 27mhz is the same exact as FM 27mhz and PCM 27mhz. Regardless of modulation, all three will "collide" with each other if on the same "channel" (or frequency).
Now, this does NOT mean you can use FM crystals in an AM radio and have it work. They are a different modulation type, yet operate (or broadcast, if you like) on the same frequency.
The advantages of AM, FM, and PCM are as follows.
AM (or Amplitude Modulation) is mostly a cost-effective alternative, but is highly susceptable to interferance from large metal objects, such as chainlink fences, cars, mobile homes, and make-or-break connections, such as throttle linkage on nitro cars.
FM (or Frequency Modulation), on the otherhand, is not prone to easily being interferred with, since it uses a "clearer" signal. The only real drawback here is the initial cost.
Then we get to PCM (or Pulse Code Modulation), typically is an FM signal, but it has the ability to additional data. These radios tend to be expensive, and are usually aircraft radios (altho Futaba did release a PCM radio back in the day).
All of your surface frequencies are broken up by bands. Here in the states, we use 27mhz and 75mhz for ground (not including toys which also use 49mhz), 40mhz and 72mhz for aircraft. 27mhz has only 6 frequencies availlable to it here in the USA. Japan, however, has a total of about 19 open.
Another myth is the myth of CB radios "cancelling" signals for modulated radios. This is not the case, at least not with FM. I have yet to try it with AM; I will have to post when I find out.
All three "modulated" types all broadcast down in the Megahertz range, unlike the new DSM setups, that all broadcast up in the Gigahertz range.
Hope that helps!
