Here is an example of a Securenet board that would be snapped on top of the personality board and connected via ribbon cable.
I am told that the radio can be either a KXJ (Secure Capable)? or KEJ (Not Secure Capable) and it will work. I can't comment on any experience with KEJ radios. It may take a firmware change but jumpers will need to be changed and the MOD comp touched up.
RFI-EMI-GUY
