The CertiFiber Pro accepts APC connectors in the INPUT port ONLY. The APC connector can be attached to the INPUT port because the INPUT port is a non-contact mating. This design feature allows you to set a 1 jumper reference for SC, ST, FC, SC/APC and LC/APC fiber testing.
The OUTPUT port uses a UPC connector. This makes a physical contact with the test reference cord. As a result, you cannot insert SC/APC connectors in the OUTPUT port of the tester. No damage will occur; you will simply get a warning from the tester about the received power being too low.
APC – Angled Physical Contact
These connectors are color coded green and are found in single mode fiber applications. The end face is slanted 8 degrees. The slight angle reduces back reflections in the core because the reflections are absorbed into the cladding. With CertiFiber Pro, you will need two hybrid UPC to APC cords and two APC to APC cords. Details on the methodology can be found in the two links below:
UPC – Ultra Physical Contact
These connectors are color coded blue for single mode and beige for multimode. The end face of the fiber has an apex so the core makes direct contact to the other core in a mated connection. A PC (Physical Contact) connector has a flat end face increasing the likelihood that an air gap will be present because the cladding can touch before the core does due to its less rounded end face geometry. That air gap with result in an increase in reflectance - something fiber systems do not want to see.