What do you mean by this? This is kinda general.
Many people make their own recordings. If you want recordings of instructors teaching a lesson or some kind of dialog without radios, I recommend getting a sound program and record yourself giving the lesson or whatever.
If you want realistic sounding
and structure concerning radio use, visit
www.adtdl.army.mil and search the library under field manuals for communications and infantry. Some of the manuals will tell you how radio operators are supposed to communicate. Once again, get a sound program and record yourself (see related posts about radio use) either through a real radio or use a filter to modify the recording to sound like a radio.
If you want generic sounds like gunfire, explosions, animal noises, etc., then yes, you may be able to find some on a 'sound library' (search for this with internet browser).
Certain sound libraries may have some generic radio chatter for use on airplanes and such, but this will usually involve extensive searching. It is best to either record your own custom sounds or hook up with someone who can make them for you. The latter is more difficult to achieve but can be most successful if you were to hook up with other specialists. As a group, you can create superior missions.