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Tektronix - 113 Delay Line

"A delay line is used in an oscilloscope to view the leading edge of the trigger event. The trigger signal is usually derived from the vertical signal path.  The trigger and sweep circuitry need about 60 ns to start so there is no signal display during this time.  A delay line placed in the vertical signal path after the trigger signal will result in the ability to display the trigger portion of the signal.

The Type 113 was a large stand-alone suitcase style 50 ohm delay line introduced in 1960 to augment sampling applications such as a Type 110 pulse generator and trigger, and a Type N sampling plug-in which does not have a built-in delay line.  The Type 113 continued in production until 1973.

The actual delay line, called “Spir-o-line”, was not manufactured by Tektronix. It was called Spir-o-line because the large center conductor (about the size of a pencil) was held inside the line with a spiral of polyethylene tubes (largely air). This image is of the 519 delay line which has a much smaller center conductor."