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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. | 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. | ||
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 | where the B timebase is shown on the same line as the A timebase, after the delay time. | ||
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 | 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== | ||