Originally Posted by
erwabo
FP-R127DF is the one that isn't working. FP-R148DP is the one that is working
Bingo!!! The FR-R148DP receiver is a PCM receiver. Since it is the one that works, it means the model you have selected in the transmitter has PCM mode enabled. It can not work with the FP-R127DF receiver which is PPM only. So, in order to use the "bad" receiver, you want to switch to a different model in your radio and set it to PPM mode.
On the Parameter display "PARA", you go to Modulation "MOD" and set it to "PPM" instead of "PCM".
Again, if you don't have the manual for the radio, you can download a copy from the Futaba website.