[Al Skierkiewicz]

Well Jim, it would seem that some experimenting might be in order but it appears that it might just work. I leave the digital part up to the software guys and Alan is one of the best or one or more of our software guys might help also. It might require some manipulating at the OI end to get enough data to make audio but the bandwidth is so limited you might just be able to do it. If you are going to Atlanta, you might want to set up a time where you can brainstorm with these guys.
As to the RC end, a mic preamp with some filtering should be easy to come up with using the LM324 quad opamp I mentioned earlier. You will need at least 50-60 dB of preamp gain since you are trying to get the audio up to at least 4 volts p-p. The 324 should be able to easily give that swing on 12 volts of power supply. Of course with the input signal being just one frequency, you might even consider using even higher gain, then limit the peaks and send it to a zero cross detector and feed that to a digital input. You could then port that to the OI and feed it to a low pass filter (2kHz) and speaker amp and still be able to decode the morse.