How can you avoid erasure of internal Comsec from the APX-123 Transponder when changing its internal battery?

• A. Disconnect power during battery change
• B. Apply power (AGPU or APU) while changing the battery
• C. Remove the battery quickly
• D. Shield the transponder enclosure

Answer: (B)

The main idea here is to prevent loss of cryptographic material (Comsec) by keeping the transponder powered during a battery change. When power is interrupted, the internal memory and secure state that hold crypto keys and related data can be cleared or become inconsistent. By supplying power through an external source (AGPU or APU) while you swap the battery, the unit remains energized, maintaining the crypto material and preventing an inadvertent erase or reinitialization.

Disrupting power during the swap would create the risk of wiping or corrupting the Comsec state, which is why not disconnecting power is not the right approach. Simply removing the battery quickly doesn’t guarantee memory preservation, and shielding the enclosure doesn’t address the memory retention issue.