Type N is a complete sampling subsystem, using the 500-series oscilloscope just as a power supply and a display. The oscilloscope is operated in X-Y mode and gets its horizontal signal from the Type N plug-in instead of from the scope's sweep circuitry. The input signal is applied through a 50 Ω GR-874 connector.
The sampling circuit of the Type N is primitive. It uses a single diode, the "interrogate diode", D5480. The strobe pulse is added to the input signal using a passive summing circuit. Consequently, the amplitude of the kick-out pulse from the input is high, about 150 mV.
The vertical scale of the Type N is fixed at 10 mV/cm, making Type N one of the few Tektronix plug-ins with fixed vertical gain. In practice, attenuators can be placed in the signal path, external to the Type N, to achieve the desired sensitivity. Using an input attenuator also has the effect of attenuating the kick-out pulse seen by the device under test.
According to Stefan Graef (http://www.messmuseum.de/tek661.htm),
The engineer behind the N was Norm Winningstad. He worked at Hughes Aircraft Electronics Division and was offered a job at HP's oscilloscope division to join their Sampling Scope team. After getting informed about the work he went to Tektronix developing the N (according to: "A narrative history of Hewlett-Packard from 1939-1990" by John Minck)
For calibration of the timebase of the Type N, the 013-028 Timing Standard was produced.
- Rise time: 600 ps (Bandwidth ~580 MHz)
- Deflection: 10 mV/Div (fixed)