Not a Spectrum or 2.4Gh. They don't seem to have much range when underwater. Any good 75Mh transmitter should work well. I'm partial towards Futaba and Polk transmitters. The Futabas have always worked well for me (I still have my first Futaba that I bought in 1992 ... works great!). The Polk is a recent addition for it's switchable electronic frequencies and mega model memory.
