Here is some additional information that may be useful as well:
http://community.cambiumnetworks.com/t5/PTP-Getting-Started/Grounding-of-PTP820S-and-PTP820C-Radio-installation/m-p/52229#U52229
http://community.cambiumnetworks.com/t5/PTP-Configuration-Examples/PTP820-C-and-S-Redundant-Power-Supply/m-p/78835#M57
http://community.cambiumnetworks.com/t5/Licensed-Microwave/can-i-use-the-PTP650-PoE-Injector-for-PTP820-radio/m-p/42939#M92