Patented Terminator Caps provide a radio frequency termination of a coaxial cable, feed-line, or hard-line, without requiring the installation of a permanent connector, or soldering of components to the cable.
Anritsu Application Note
June 17, 2016
Anritsu Application Accuracy of DTF Measurements on New Spools of Transmission Line discusses proper technique for making accurate Distance to Fault Measurements. It states "The DTF return loss of the entire spool can be accurately measured but requires putting a termination on the far end of the cable." See Anritsu Application Notes:
Terminator Caps simply slip over the end of a cable with a firm press fit.