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The '''Tektronix Type 221''' is a miniature 5 MHz analog scope [[introduced in 1973]].
The '''Tektronix Type 221''' is a miniature 5 MHz analog scope [[introduced in 1973]].


It has a switching power supply and built-in rechargeable batteries (which are
{{MissingSpecs}}
 
==Internals==
The 221 has a switching power supply and built-in rechargeable batteries (which are
a maintenance issue).  It has a transformer-coupled trigger circuit which  
a maintenance issue).  It has a transformer-coupled trigger circuit which  
would seem to preclude DC level-based triggering.  The trigger circuit uses a  
would seem to preclude DC level-based triggering.  The trigger circuit uses a  
[[1N3713]] 1mA [[tunnel_diodes|tunnel diode]].  The vertical output amplifier  
[[1N3713]] 1 mA [[tunnel_diodes|tunnel diode]].  The vertical output amplifier  
that drives the CRT plates is two opamps made from discrete transistors.  One  
that drives the CRT plates is two opamps made from discrete transistors.  One  
drives the top deflection plate and the other drives the bottom plate.
drives the top deflection plate and the other drives the bottom plate.
==Specifications==
''please add''


==Pictures==
==Pictures==


<gallery>
<gallery>
Image:Tek 221 1.jpg|Front
Tek 221 1.jpg|Front
Image:Tek 221 right.jpg|Panel of 221
Tek 221 right.jpg|Panel of 221
Image:Tek 221 probe.jpg|Probe of 221
Tek 221 probe.jpg|Probe of 221
Image:221-5.jpg|221 with orginal bag
221-5.jpg|221 with orginal bag
Image:221-2.jpg|221 on top of 565
221-2.jpg|221 on top of 565
</gallery>
</gallery>


[[Category:200 series scopes]]
[[Category:200 series scopes]]
[[Category:Specifications needed]]