Edgar wrote:

Dear fellows,
What kind of mode F3C? RTTY or what? How it is tuned on communication
receiver using AM,CW,LSB,USB,FM or what?

Well, it's frequency shift keying and as far as I know commonly used for RTTY.

You'd most likely tune it using either LSB or USB.

Someone more well versed in the digital modes can probably give you a better,
more detailed answer.

You might wish to join up with WUN, they do a lot of digital mode stuff:

http://www.wunclub.com/

dxAce
Michigan
USA