Please be advised that we are the Futaba service and support center for North America.

Since Futaba doesn't have an AM module for transmitters other than the 3PK, and states that the 3PK module is for the 3PK transmitter only, we'd suggest that it only works that way. Since PCM receivers only use FM modulation, trying to transmit an AM signal with the transmitter set to PCM would not work.

We don't know of an AM module for the current and recent airplane transmitters (7U, 8U, 9C, etc). At least not for North America.

You may wish to contact the Futaba distributor for Hong Kong to see what options are available to you.