Can the C5x base radio at 8 dBi be used without an antenna?
Yes. You can use the base C5x 8 dBi radio without an antenna for short distance links. Please remove the locking screw from the twist-on screws to serve as a drain hole.
Do I have to install a feature key when initially unlocking the C5x?
No. As of March 1, 2019, feature keys are no longer necessary or available. Out of the box, the C5x can be used to its full potential — speeds of up to 700 Mbps in PTMP or PTP mode.