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{{Oscilloscope Sidebar |manufacturer=Tektronix |designers=Wink Gross;Oliver Dalton;Glenn Bateman|
{{Oscilloscope Sidebar
series=400-series scopes |
|manufacturer=Tektronix
model=485|
|series=400-series scopes
image=Tektronix 485 oscilloscope2.jpg|
|model=485
caption=Tektronix 485|
|image=Tektronix 485 oscilloscope2.jpg
introduced=1972 |
|caption=Tektronix 485
discontinued=1986 |
|introduced=1972
summary=350 MHz portable scope|
|discontinued=1986
manuals=
|summary=350 MHz portable scope
* [http://bama.edebris.com/download/tek/485/tek-485.pdf Tektronix 485 Manual (PDF)]
|designers=John Addis;Wink Gross;Gene Andrews;Glenn Bateman;Ron Peltola;Bob Firth;Murlan Kaufman;Bob White;Keith Taylor;Dick Troberg
* [[Media:Tek-485 OCR.pdf|Tektronix 485 Manual (PDF), OCR]]
|manuals=
* [[Media:070-1193-00.pdf|Tektronix 485 Manual (PDF, OCR, bad-OCR)]]
* [[Media:070-1193-00.pdf|Tektronix 485 Manual]] (bad-OCR)
* [[Media:Tek 485 cal proc.pdf|Tektronix 485 Calibration Procedure (PDF)]]
* [[Media:Tek-485 OCR.pdf|Tektronix 485 Manual]] (OCR)
 
* [http://bama.edebris.com/download/tek/485/tek-485.pdf Tektronix 485 Manual]
* [[Media:Tek 485 cal proc.pdf|Tektronix 485 Calibration Procedure]]
}}
}}
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 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.  
where the B timebase is shown on the same line as the A timebase, after the delay time. At the same 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).


The 485 uses the [[154-0652-00]] and [[154-0652-05]] CRTs.
Variant 485-1 omits the "A EXT Trigger display", as does variant 485-2 which additionally only has 50 Ω inputs.
 
[[John Addis]] was project leader for the vertical section, assisted by [[Wink Gross]].
[[Glenn Bateman]], [[Ron Peltola]] and [[Bob Firth]] designed the low- and high-impedance attenuators.
[[Murlan Kaufman]] was project leader for the horizontal and logic systems and designed the trigger generator.
[[Bob White]] designed the trigger amplifier and external trigger view circuits.
[[Keith Taylor]] did the work on the fast sweeps, the horizontal and the Z-axis amplifiers.
[[Dick Troberg]] designed the high efficiency power supply system.


{{BeginSpecs}}
{{BeginSpecs}}
{{Spec | Input Impedance  | 50 Ω / 1 MΩ // 20 pF }}
{{Spec | Input Impedance  | 50 Ω / 1 MΩ // 20 pF }}
{{Spec | Rise time | 1 ns (50 Ω) / 1.4 ns (1 MΩ) }}
{{Spec | Rise time       | 1 ns (50 Ω) / 1.4 ns (1 MΩ) }}
{{Spec | Bandwidth | 350 MHz (50 Ω) / 250 MHz (1 MΩ) }}
{{Spec | Bandwidth       | 350 MHz (50 Ω) / 250 MHz (1 MΩ) }}
{{Spec | Deflection | 5 mV/div to 5 V/div in 1−2−5 sequence, 2% accuracy }}
{{Spec | Deflection       | 5 mV/div to 5 V/div in 1−2−5 sequence, 2% accuracy }}
{{Spec | Time Base | 1 ns/div to 0.5 s/div in 1−2−5 sequence}}
{{Spec | Time Base       | 1 ns/div to 0.5 s/div in 1−2−5 sequence}}
{{Spec | CRT              | [[154-0652-00]] and [[154-0652-05]], 21 kV acceleration, 8 × 10 divisions (0.8 cm/div)}}
{{Spec | Weight          | 9.3 kg (21.5 lb) }}
{{Spec | Power            | AC 90–136 or 180–272 V, 48–440 Hz, 60 W @ 115V }}
{{EndSpecs}}
{{EndSpecs}}


==Links==
==Links==
* [http://www.amplifier.cd/Test_Equipment/Tektronix/Tektronix_other/485.html Tek 485 @ amplifier.cd]
* [[Gene Andrews]], ''A nanosecond portable oscilloscope''. In [[Media:Tekscope_1972_V4_N2_Mar_1972.pdf|Tekscope Vol.4 No.2, March 1972]], p.2+.
* [https://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
* [https://www.youtube.com/watch?v=P56MyUK3n18 485 Restoration and Repair] @ Zenwizard Studios YouTube
* [https://www.youtube.com/watch?v=95rlRAlRT5k 485 Power Supply and Tube Alignment] @ Zenwizard Studios YouTube
* [https://www.youtube.com/watch?v=mJa5jap968w 485 Horizontal Alignment] @ Zenwizard Studios YouTube
* [https://www.youtube.com/watch?v=lVsLMrCnOK4 485 Vertical and Trigger alignment] @ Zenwizard Studios YouTube
==Prices==
{| class="wikitable"
|-
! Year
! 1972
! 1973
! 1976
! 1980
! 1982
! 1986
|-
! Catalog Price
|align=right| $4,200
|align=right| $4,200
|align=right| $4,550
|align=right| $6,035
|align=right| $6,975
|align=right| $9,100
|-
! In 2023 Dollars
|align=right| $30,900
|align=right| $29,100
|align=right| $24,600
|align=right| $22,500
|align=right| $22,200
|align=right| $25,600
|}


==Maintenance issues==
==Internals==
A healthy Tek 485 CRT has been observed to have a filament current of 98 mA.
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]].
A broken Tek 485 CRT that lost its vacuum was observed to have a filament current of 153 mA.


==Pictures==
==Pictures==
===External===
<gallery>
<gallery>
Tek 485 trace.jpg
Tek 485 trace.jpg
Tek_485_Trace.jpeg
Tektronix 485 oscilloscope2.jpg
Tektronix 485 oscilloscope2.jpg
Tek 485.jpg
Tek 485.jpg
Tek 485 front2.jpg
Tek 485 front2.jpg
Tek 485 front.jpg
Tek 485 front.jpg
Tek_485-rear.jpeg
Tek 485 rear.jpg
Tek 485 rear.jpg
Tektronix 485 oscilloscope5.jpg
Tektronix 485 oscilloscope5.jpg
Tek 485 tq.jpg
Tek 485 tq.jpg
Tek_485_A-Ext-Trig-Display.jpeg | Time base A, External trigger display switch
USA Tektronix 485 Inside1.jpg
USA Tektronix 485 Inside1.jpg
</gallery>
===Internals===
<gallery>
Tek_485-Top.jpeg | Top, Horizontal Amp board
Tek_485-Underside.jpeg | Underside, Power supply, A-Trig board
Tek_485-RHS.jpeg | LHS, Vertical Amp board
Tek_485-LHS.jpeg | RHS, Sweep/Inverter board
Tek_485-A-Trigger-bd.jpeg | A-Trigger board
Tek_485-attenuator-Assy.jpeg | Vertical attenuator Assy
Tek 485-attenuator-Inside.jpeg | Vertical attenuator Assy, 50Ω Board
Tek_485-Hi-Z-attenuator-bd.jpeg | Vertical attenuator Assy, Hi-Z Board
</gallery>
</gallery>


{{Custom ICs|485}}  
==Components==
{{Parts|485}}  


[[Category:400 series scopes]]
[[Category:400 series scopes]]
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