[Al Skierkiewicz]

John,
What you might want is a mic preamp. It is fairly easy to build one with parts from Radio Shack. An LM324 is a quad opamp optimized for a single ended power supply. What you might want to add to this arrangment is a DTMF emitter with a DTMF decoder following the preamp. This will give you a digital type output where you can use one of 10 switch closures. Morse code is OK but it is difficult to decode unless the code is generated through an electronic device that has controlled timing. Morse readers are available but are fairly complex devices as you problably know. DTMF decoders have built in filtering that will help in noisey environments. Several vendors sell kits for this. Ramsey I think has a few different kits. They are the ones that make some nice little devices for hams and they have an internet site. You also might want to check out MCM.