485: Difference between revisions

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The '''Tektronix 485''' is a dual-trace, portable analog oscilloscope with a maximum  
The '''Tektronix 485''' is a dual-trace, portable analog oscilloscope with a maximum  
bandwidth of 350 MHz. The impedance of the inputs can be set individually to 50 Ω or 1 MΩ.   
bandwidth of 350 MHz, [[introduced in 1972|introduced in March of 1972]].
The project leader for the horizontal section of the 485 was [[Murlan Kaufman]].
 
The impedance of the inputs can be set individually to 50 Ω or 1 MΩ.   
The scope achieves its maximum bandwidth when the inputs are in 50 Ω mode.   
The scope achieves its maximum bandwidth when the inputs are in 50 Ω mode.   
The 485 was [[introduced in 1972|introduced in March of 1972]].  It includes a switching
power supply and uses [[155-0078-00|custom integrated circuits]] for most of the gain blocks. 
Triggering uses [[tunnel diodes]].


A distinguishing feature – at least in a portable oscilloscope of its period – is the Alternate Horizontal Mode.
A distinguishing feature – at least in a portable oscilloscope of its period – is the Alternate Horizontal Mode.
In this mode, the B timebase is shown in a separate full-width scan, as opposed to the more common Mixed Mode,  
In this mode, the B timebase is shown in a separate full-width scan, as opposed to the more common Mixed Mode,  
where the B timebase is shown on the same line as the A timebase, after the delay time. At the same time,
where the B timebase is shown on the same line as the A timebase, after the delay time.  
The project leader for the horizontal section of the 485 was [[Murlan Kaufman]].


The [[465]], which was introduced after the 485, only received this feature in its "B" incarnation (465B).
The [[465]], which was introduced after the 485, only received this feature in its "B" incarnation (465B).


485-1 is without "A EXT Trigger display" and 485-2 is without "A EXT Trigger display" and only 50Ω input.
Variant 485-1 omits the "A EXT Trigger display", as does variant 485-2 which additionally only has 50 Ω inputs.


{{BeginSpecs}}
{{BeginSpecs}}
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* [http://www.amplifier.cd/Test_Equipment/Tektronix/Tektronix_other/485.html Tek 485 @ amplifier.cd]
* [http://www.amplifier.cd/Test_Equipment/Tektronix/Tektronix_other/485.html Tek 485 @ amplifier.cd]
* [https://youtube.com/watch?v=7Qg6ory3L8Y 485 troubleshooting] @ YouTube
* [https://youtube.com/watch?v=7Qg6ory3L8Y 485 troubleshooting] @ YouTube
==Internals==
The 485 includes a switching power supply and uses [[155-0078-00|custom integrated circuits]] for most of the gain blocks.  Triggering uses [[tunnel diodes]].


==Maintenance issues==
==Maintenance issues==