Horizon Hobbies has announced conversion sets called "Air Modules", that allow use of some existing JR and Futaba transmitters with the Spektrum 2.4 GHz DSM2 technology. The Air Modules consist of a replacement plug-in frequency module and antenna for the transmitter, and new 7 or 9-channel receivers. For example, both my Futaba 9CAP and my JR 8103 may be converted. However, a complete Spektrum radio, complete with servos, costs about the same as an Air Module, so it looks like this might be a good deal only if you have a very expensive JR or Futaba transmitter, like the 10X or the MZ.  Also, the transmitter modules are limited to 8 channels. You must operate the transmitter in PPM mode, but all your programming for your individual models is retained, as long as you used no more than 8 channels. See the Spektrum website.