Delay line
The first Tektronix scope to contain a delay line was the 513D, which uses an L-C network. Soon after, the 517 appeared, using a coaxial cable as a delay line. 7000-series scopes use special twin-lead delay cables. The delay line in the 519 is a large coil of low-loss air-dielectric rigid coax.
Some delay lines are at the input. Some are between amplifiers. Some, such as the in the 516, are between the final amplifier and the CRT vertical deflection plates.
Delay lines have a similar purpose in sampling scopes.
There are four main ways delay lines are implemented in Tektronix scopes: