Beenthere,
I have this article as NOT inverter for FSK. Does this mean I can remove the MAX232 from the TNC circuit? (KE4NYV's TNC)

Also, the article only references 'output'. What does one do for input into the circuit from the walkie?

Thanks, Bob

 

Let's put this in its own thread. Hijacking an old post is always confusing - http://forum.allaboutcircuits.com/showthread.php?t=12044

FSK is simply doing modulation with two tones. That article shows how to switch tones quite simply. And, if you leave then in the audio range, they can be input to any walkie-talkie as a vox input. Figure out how to key the TX and you're there.