The Tektronix 2901 Time Mark Generator is a compact, wide-range unit. It is crystal-controlled and provides 16 marker intervals, 4 sinewave frequencies, and 8 trigger-pulse intervals. . Time mark outputs range from 1 µs to 5 s in 16 steps. Sinewave outputs are: 2 ns; 5 ns; 10 ns and 50 ns. Trigger output and external clock input are also provided