This section describes the devices in the signal path at a VLBA antenna site. Devices in Sections 5.1-5.6 and 5.8-5.11 are located at the antenna; all others are in the site control building. More information on the VLBA signal path is provided by Napier (1995), Thompson (1995), and Rogers (1995). In collaboration with the South African KAT group, MIT Haystack Observatory, and the CASPER group at UC Berkeley, NRAO currently is developing a digital back end that will enable data to be delivered to recording systems at a rate of 4 Gbps. We expect the new back end systems to be implemented in 2009. At that time, subsections 6.13 through 6.15 will become obsolete.