Exchanging faulty Cryptographic equipment needing repair at the Squadron/Operational site with a serviceable spare unit. Forwarding the failed unit to the Central Repair Facility of Secure Comm. equipment for further analysis and repair to the component level. Therefore, the technician must be familiar with standard trouble shooting tools and devices such as Huntron Tracker and General Purpose Electronic Test Equipment (GPETE) for isolating faults to sub-assembly and component level.