How does the KWD-AE31 DES/AES encryption module install into the NX-5x00 mobile? Do you use the little flex cable that comes with it, or just plug it in directly?
You use the flex cable.
From the manual:
1. Remove the cabinet, top packing and shielding plate from the transceiver.
2. Attach the cushion B and C to the module backside.
3. Fold the release paper as indicated in the figure. (This is shown in the manual, can't show it here)
4. Insert the connector of the module CN731 of the TX/RX PCB.
5. Pull and remove the release paper while pressing down on the module with your finger to hold it in place.
You'll need to tell the radio via the programming software that you now have the SCM (Secure Cryptographic Module) installed in the radio, or it won't let you program any of the SCM functions.