155-0137-00
The Tektronix H493 (P/N 155-0137-00) is a pre-amp/comparator hybrid integrated circuit in a ceramic package. It was designed by Oscar Olson.
It contains five comparators with FET inputs and differential ECL outputs that can drive terminated 100 Ω twisted-pair lines. The instrument input would contain differential ECL receivers like the 10115 or 10216.