Thus, an EF-compliant test method must have a way to control the launch condition itself so that the output launch exiting the multimode reference cable is consistent regardless of what test source and/or reference cables are used.

This is done by using a special reference cable called a Mode Controller (like the one shown here). Mode Controllers includes a special in-line module that ensures a consistent launch pattern at the output connector, regardless of what multimode light source is used.

But you have to be careful with mode controller cables. They cost several hundred dollars each, and if the output connector becomes damaged in any way, the mode controller is no longer EF-compliant.

Also, the output is limited to one connector type, so if you work with various connector types on a regular basis, you would technically need multiple mode controllers.

And, regular patch cables cannot be used to protect the endface because the output would no longer be EF-compliant.

Thankfully, extender cords, otherwise known as REFERENCE-GRADE test cables, are an acceptable way to protect this investment. Extender cords:

• maintain EF compliance
• protect the fragile mode controller output connector
• are less expensive to purchase multiple extender cords than multiple mode controllers
• are less expensive to replace than mode controller cables