Yeah the Spectrum and the JR's use practically the same firmware programming...

Heck the Spectrum's screen looks identical to my old 8103's.

Remember that the "master" controller must be on, and the slave off.

Also the trims, expos and endpoints on both radios must be seperately set up, but identical.

After you have it working, check this by deflecting a surface identically on both radios, and flipping the trainer switch.

If the surface stays at the same deflection when you flip the switch, then both radios have the trims and endpoints the same.

Do this with ALL surfaces and directions.