View source for 7A21N

{{Plugin Sidebar
|manufacturer=Tektronix 
|series=7000-series scopes
|type=7A21N 
|summary=Direct Access plug-in
|image=Tek 7a21n front.jpg 
|caption=7A21 front panel 
|introduced=1972 
|discontinued=1979 
|designers=
|manuals=
* [[Media:070-1367-00.pdf|Tektronix 7A21N Manual]]
* [[Media:070-1962-00.pdf|Tektronix 7A21N Manual]] (SN B040000-up)
}}
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]].

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 [[7000 series readout system|readout facility]] and second vertical plug-in bay.  

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

==Links==
{{Documents|Link=7A21N}}
{{PatentLinks|7A21N}}

==Pictures==

<gallery>
Tek 7a21n front.jpg|7A21N front
7a21 right.jpg|7A21N right
Tek 7a21 left.jpg|7A21N left (including vertical amp replacement boards)
Tek_7a21_rear_conn.jpg|7A21N rear
7a21n-accessories-manual.jpg | Standard accessories
</gallery>

Precursor/prototype to the 7A21N:
<gallery>
Tek 7a21n precursor 1.jpg
Tek 7a21n precursor 2.jpg
Tek 7a21n precursor 3.jpg
</gallery>


[[Category:7000 series vertical plugins]]