To make sure I understand it right. A preselector added in between the RXA input and RXA output will have EMP protection or do I have to have protection added myself. This is only in the single antenna, one receiver situation. Only using single SCU. Thanks.
Unlikely that a preselector would provide meaningful EMP protection. For true EMP, about the only thing that gives you a chance is disconnection and isolated, shielded storage. For lightning protection, also unlikely the preselector will save you from a direct strike. It might be the "sacrificial" component in some cases, it I wouldn't count on it for any protection.
The EMP protection for the 6700 is done in the SCUs. There are sacrificial ESD diodes before and after the preselector filters. There is also a disconnect relay to ground the RF input signal path if the input signal threshold approaches the damage point of the SCU. All of this is after the antenna switching matrix. So any device in the RX Loop is before any of the the ESD protection.