ORIGINAL: Person_X
the Optic 6 with the Spectra module supports BOTH positive AND negative shift RX's, hence all hitec and futaba's and all of the JR's and Airtronics that are positive shift. it also supports PCM RX's
Good post except one point, PCM is not generic. PCM is specific to brand and in some cases it is specifc to models within brands. FM/PPM can mix brands. Generally you can not mix brands of PCM RX/Radios.
PCM and PPM are both using an FM radio band. They code the information differently. When people say FM, they mean FM/PPM. When they say PCM they mean FM/PCM. Hitec has QPCM too which works with the newer Hitec Eclipse7 and Optic 6 radios. It will not work with older Hitec PCM radios such at the Hitec Prism 7X.