7A21N

Manuals – Specifications – Links – Pictures

The Tektronix 7A21N is a 7000-series plug-in that provides direct access to the CRT for fast-risetime AC signals on the 500 MHz-class 7900 series scopes, i.e. 7904/7904A, R7903, 7934, R7912. It was designed by Bruce Hollister.

Input signals are applied via a pair of GR-874 connectors.

The 7A21N is fully passive. It can be wired for single-ended or differential signals internally. It includes two delay lines, two inverting "transformers", and a passive bridge and power divider. There is no trigger pick-off, i.e. the trigger signal will have to be provided externally, e.g. through a 7M11.

The 7A21N is intended to be installed in the Left Vertical bay of the 79xx mainframe and requires the mainframe's vertical amplifier board to be replaced with the 7A21N CRT Input Network and 7A21N CRT Termination boards, which are shipped plugged into the back side of the 7A21N circuit board. (A second-hand 7A21 without these boards and associated cables is useless!)

Obviously, installing the replacement boards also disables the mainframe's readout facility and second vertical plug-in bay.

Key Specifications

Deflection	< 4 V/Div (SE), < 2 V/Div (Differential)
Bandwidth	20 kHz – 1 GHz
Input impedance	50 Ω
Max. input	6 W avg @ 50 Ω, 200 V DC

Pictures

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  7A21N front

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  7A21N right (cables connected for single ended operation)

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  7A21N left (including vertical amp replacement boards)

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  7A21N rear

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  Standard accessories

Precursor/prototype to the 7A21N:

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