Can theFrame Relay Tester 660 Frame test an E1 line that is Fiber?

Yes. There is usually a piece of termination hardware on the fiber cable that has test access jacks (bantamor coax BNC style jacks). Then connect the Tx and Rx sides from the 660 to the test access connectors marked "IN" and "OUT" to terminate the line. Connect the Rx side from the 660 to the test access connectors marked "Monitor" to tap into an in-service circuit.