The 155-0181-00 (H500) is a Tek-made Input Amplifier thin-film circuit (using an M199 amplifier die) in a Hypcon package. It was designed by John Addis and uses the "ft doubler" circuit patented by Carl Battjes.
The circuit has a single-ended 50 Ω input and push-pull outputs with a gain of up to 3.55 into a push-pull 50 Ω load. Gain may be varied from 3.55 to 0 and inverted to -3.55 by adjusting the ratio of two DC currents. At full gain, the risetime is 180 ps or less, but lower at reduced gain.
155-0181-00 in 7F10