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The Tektronix 549 is the only storage scope that takes a letter-series or 1-series vertical plug-in. It was made in the mid 1960's. The vertical -3dB bandwidth is 30MHz.
{{Oscilloscope Sidebar
|manufacturer=Tektronix
|series=500-series scopes
|model=549
|summary=30 MHz storage oscilloscope
|image=Tek-549 and d.jpg
|caption=Tektronix 549 front
|introduced=1965
|discontinued=1974
|designers=Mel Holznagel;Bob Shand;
|manuals=
* [[Media:070-0508-00.pdf | Tektronix 549 Manual]] (OCR)
* [https://w140.com/mmm/tek-549.pdf Tektronix 549 Manual]
* [https://bama.edebris.com/manuals/tek/549 Tektronix 549 Manual] @ BAMA


Like many Tek scopes from the period, it uses a mix of transistors and tubes.  For example, consider the buffer amplifier in the 549, whose purpose is to interface the high-impedance output of the plug-in with the low-impedance of the 200 nanosecond delay line in the 549.
====Maintenance Notes====
As is usual in oscilloscope vertical circuits, the requirement is to have flat frequency response from DC to the maximum frequency of the scope and to have linear phase response over this same frequency range.  In the 549, this buffer is implemented as follows:  A [[6DJ8]] tube configured as a cathode follower is used at the interface with the plug-in to present a high impedance to the plug-in. This input stage drives an NPN BJT differential amplifier, which operates at the bottom of a cascode configuration with a [[7119]] tube on top.  The output of the cascode (the plate of the 7119) drives the delay line.  Since the entire signal path is differential, the common-mode voltage does not have to be zero, and it is not; the differential signal in the delay line rides on 167 volts of DC.  After the delay line, the signal enters another cascoded differential amplifier with
* [[Media:tek_549_crt_socket_leak.pdf|Maintenance Note: 549 CRT Socket Leakage]] (OCR)
NPN BJTs on the bottom and [[8608]] tubes on the top.  The vertical deflection plates of the CRT are driven by the plates of a 8608 10-watt power pentode, through inductive matching/peaking networks.  The 549 is unusual among 54x-series scopes in that it does not use a distributed vertical amplifier.
* [[Media:tek_549_note_ringing_1a1.pdf|Maintenance Note: 549 Ringing with 1A1]] (OCR)


====Data Sheets and Catalogs====
* [[Media:tek_549_catalog.pdf|Tektronix 549 in 1968 Catalog]] (OCR)
* [[Media:tek_549_german_intro.pdf|Tektronix 549 Introduction in German]] (OCR)
* [[Media:tek_549_Remote_Control_DS.pdf|Tektronix 549 Remote Control Datasheet]] (OCR)
}}
The '''Tektronix 549''' is the only [[CRT_storage_scope|storage scope]] in the 500 series (except for the [[537]] that never left prototype stage).
It takes a [[Letter-series_and_1-series_plug-ins|letter-series or 1-series vertical plug-in]].
The 549 was [[introduced in 1965]] and discontinued after 1973. 
The 549 vertical output stage was designed by [[Mel Holznagel]].  [[Bob Shand]] did the mechanical design.
{{BeginSpecs}}
{{Spec | Bandwidth | DC to 30 MHz (−3 dB) with fast plug-ins ([[1A1]], [[1A2]], [[1A4]], [[1A5]]) }}
{{Spec | Rise time | 12 ns }}
{{Spec | Writing speed | 5 cm/μs }}
{{Spec | Line voltage  | 104/115/127 or 208/230/254 V<sub>AC</sub> ±10%, selected via primary voltage selector (inside cabinet) and voltage range selector (on rear panel), 50 to 60 Hz }}
{{Spec | Thermal protection | 65°C (150°F) Automatic resetting [[thermal cutoff]] }}
{{Spec | Power consumption | 650 W, 750 VA }}
{{Spec | Size    |  43.2 cm × 32.9 cm × 60.7 cm (W/L/H, 13" × 24" × 17")  }}
{{Spec | Weight  | 31 kg (68 lb) }}
{{Spec | Cooling  | AC Fan }}
{{Spec | Accessories  | [[012-0102-00|012-0102-00 remote control cable/switch]] }}
{{EndSpecs}}
==Internals==
=== Mix of Transistors and Tubes ===
Like many Tek scopes from the period, the 549 uses a mix of transistors and tubes. 
For example, consider the buffer amplifier in the 549, whose purpose is to interface
the high-impedance output of the plug-in with the low-impedance of the 200 ns delay
line in the 549. As is usual in oscilloscope vertical circuits, the requirement is
to have flat frequency response from DC to the maximum frequency of the scope and
to have linear phase response over this same frequency range. 
In the 549, this buffer is implemented with a [[6DJ8]] cathode follower at the plug-in interface
driving an NPN BJT differential amplifier at the bottom of a cascode with a [[7119]] tube on top. 
The output of the cascode (the plate of the 7119) drives the [[delay line]]. 
Since the entire signal path is differential, the common-mode voltage does not have to be zero,
and it is not – the differential signal in the delay line rides on 167 volts of DC. 
After the delay line, the signal enters another cascoded differential amplifier with NPN BJTs
on the bottom and a pair of 10-watt [[8608]] power pentodes on the top whose plates drive the
CRT's vertical deflection plates of the CRT through inductive matching/peaking networks.
===Non-Distributed Amplifier=== 
The 549 is slightly unusual among 54x-series scopes in that it does not
use a [[distributed amplifier|distributed vertical amplifier]].
(Other exceptions include the [[545|545B]] and [[547]]).
===Triggering===
Triggering is done using an NPN BJT Schmitt trigger.
Triggering is done using an NPN BJT Schmitt trigger.


The screen has two storage targets, upper and lower, whose storage mode and erase signals can be controlled independently.
===Storage===
The 549 uses the [[T5490]] CRT which has two storage targets, upper and lower,
whose storage mode and erase signals can be controlled independently.
 
The [[012-0102-00|012-0102-00 remote control cable/switch]] (also used for [[564B]]) can be used to remotely erase the screen and reset the single sweep.
It connects to an [[Amphenol 165 series connectors|Amphenol 165-16 socket]] at the rear top of the scope (see [[549 remote control connector]] for pin-out).
 
===Power Supply===
The 549's power supply provides regulated outputs of −12.4 V, −150 V, +100 V, +225 V, +300 V, +350 V, and +500 V as well as a +475 V unregulated output.
 
Line input is connected to main transformer primary via two switches, one inside the chassis to select the 110 V or 230 V range, and another on the rear of the chassis to select Low/Medium/High voltage in either range.
 
Multiple secondary windings feeds diodes for rectification for different voltages. Both center-tap and bridge configuration is used. Transistors and/or tubes are used for regulation.
 
As is common in many Tektronix scopes, all regulated voltages are referred to the negative regulated rail (−150 V in this case) by fixed low-tolerance dividers.  Only the −150 V voltage is trimmed, its reference is a [[5651]] VR tube.  A [[12AX7]] is used as the comparator, three [[12B4]] in parallel are used as series pass tubes. A [[6AU6]] is used as an error amplifier.
 
Most other stages replicate the same design, except slight changes in tubes used − the +350 V, +225 V and +100 V regulators employ a [[6080]] as the pass element.


* [http://bama.edebris.com/manuals/tek/549 549 manual on BAMA]
The −12.4 V regulator is transistor-based.


The 549 power supply uses a [[delay relay|6N030 delay relay (P/N 148-0021-00)]] to control a relay that switches supply voltages on only after the tubes are warmed up. On power up, only heater voltage is applied to the tubes.  After a delay of up to 60 seconds, the thermal delay relay activates the main relay (driven from unregulated +170 V). This also cuts out the delay relay, which can cool down and will be ready to delay again even after a quick interrupt in power input.
The 549 has a 65°C (150°F) [[thermal cutoff]].
The 549 uses a [[120-0423-00]] HV transformer driven by a [[6GF5]] tube from +470 V.
===HV Transformer Problem and Replacement===
The HV transformer (part #120-0423-00) uses epoxy impregnation like models 544,545B,546,547,556 and as such suffers the same issue of increasing losses with age unlike the earlier bee's wax transformers. This issue will eventually lead to failure of the HV oscillator circuit resulting in loss of display intensity, blooming and finally vanishing trace. One solution is to use a donor HV transformer out of a 564 storage scope. This was successfully implemented by Morris Odell and Deon Vandenberg however invented by another. A photo is provided below showing the new transformer installed with terminals arbitrarily labelled to help others perform the same task. Looking at the photo the top connections are obvious. The left middle connection goes to the right strip pin 9 (labelled as 9) The bottom section has two connections, one on the left towards the neons(labelled A) this goes to the anode of the driver tube V800 pin 7. The other obscured wire is the bottom left which goes to the 4th pin on the left strip (labelled as 4). Resistor R807 is to be changed from 39k to 47k. Resistor R2 is to be added between the junction of D836 and C842 and R837. (See schematic.) When this is done adjust the HT at the test point to -3700V (R855) and adjust R815 to make the grid voltage -3790V (located at test point labelled TP). To see the new transformer in action click on the bottom youtube link.
==Links==
* [https://lazyelectrons.wordpress.com/2018/01/11/tektronix-549-restoration/ Rajesh's Tek 549 Restoration] / [https://www.youtube.com/watch?v=8rWH-uuf60U Video]
* [http://www.radiomuseum.org/forum/tektronix_the_storage_story.html Tektronix, the Storage Story]  (1966) @ radiomuseum.org
* A [https://www.youtube.com/watch?v=1SRtm7eva0A 549 @ YouTube]
* [https://www.youtube.com/watch?v=D6szONQe1go&t=6s Deon's 549 with 564 HT Transformer]
==Pictures==
<gallery>
Tek-549 and d.jpg                | 549 front, earlier round bezel
Tek 549 mt1.jpg                  | 549 front, later rectangular bezel
Tek-549-front.jpg
Tek 549 trace2.jpg              |
Tek_549-Front.jpeg              |
Tek_549-Stroage-Ctrl.jpeg        | 549 Storage controls
Tek 549 trace2..jpg              |
Tek 549 trace.jpg                |
Tek 549 front fl.jpg            |
549_front.jpg                    | Front of a 549
Wellenkino 549-1.jpg            |
Tek 549 front fl.jpg            |
Tek 549 1a4 1.jpg                |
Tek 549 1a4 2.jpg                |
Tek_549-Rear.jpeg                | 549 Rear 
Tek_549-Line-Range.jpeg          | Line voltage selector           
Tek 549 1a4 3.jpg                |
Tek 549 1a4 4.jpg                |
549_Delayed_Trace.jpg            | B INTEN BY A Trig in 549
549_Dual_Trace.jpg              | Dual trace display in 549
Tek 549-1 knob layout.jpg        | 549 knob layout
Tek 549 - Electronics 1965-08-23.jpg | 549 ad in Electronics 1965-08-23
</gallery>
===Internal===
<gallery>
<gallery>
Image:549_front.jpg|Front of a 549.
Tek_549-LHS.jpeg                | LHS
Image:549_vert_amp.jpg|Vertical amp.
Tek_549-RHS.jpeg                | RHS
Image:549_top.jpg|Top view.
Tek_549-RHS-Timebase.jpeg        | RHS Timebase Ch: Door Open
Image:549_storage_board.jpg|Storage board.
Tek_549-Top.jpeg                | Top
Image:549_inside_door.jpg|Power supply behind door.
Tek_549-Under.jpeg              | Underside
Tek_549-V-Amp.jpeg              | 8608 vertical output tubes
549_vert_amp.jpg                 | Vertical amp
549_Vertical_OP.jpg              | 8608 vertical output tubes
Tek 549 vertamp on.jpg          | 8608 vertical output tubes
549 v out.jpg
549_top.jpg                     | Top view
549_storage_board.jpg           | Storage board
549_inside_door.jpg             | Power supply behind door
Wellenkino_549-8.jpg            | Right side internal
Wellenkino 549-7.jpg            |
Wellenkino 549-6.jpg            |
Tek_549-Prim-Sel-Sw.jpeg        | Primary voltage range selector
549_Tubes_ON1.jpg                | LV power supply tubes
549_Tubes_ON.jpg                | LV power supply tubes
Tek_549_Storage_Board.jpg        | Storage board Rev "PC" (recapped)
Tek_549-storage_board_Rev_PE.JPG | Storage board Rev "PE"
</gallery>
</gallery>
===HT Transformer modification===
<gallery>
564 HV Transformer installed in the 549.jpeg  | 564 HV transformer installed in the 549
Schematic of HT transformer modifications.jpeg | Schematic showing other changes required
</gallery>
==Components==
{{Parts|549}}
[[Category:500 series scopes]]
[[Category:Introduced in 1966]]
[[Category:Analog storage scopes]]
 
Retrieved from "https://w140.com/tekwiki/wiki/Special:MobileDiff/1083...90629"