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C808 high DF self-heats and causes HV thermal runaway
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{{Oscilloscope Sidebar |
{{Oscilloscope Sidebar  
title=Tektronix 547 |
|manufacturer=Tektronix
summary=50 MHz scope |
|model=547  
image=Tek 547 trace.jpg |
|summary=50 MHz oscilloscope
caption=Tektronix 547 with [[1A2]] plugin |
|image=Tek 547 D-Alt-Trace.jpeg
introduced=1964 |
|caption=Tektronix 547 with [[1A1]] plugin, in ALT Delayed Trigger 
discontinued=1975 |
|introduced=1964  
manuals=
|discontinued=1975  
* [http://w140.com/mmm/tek-547.pdf Tektronix 547 Manual with 547 Notes (PDF, 128MB)]
|designers=Bob Rullman;Keith Taylor;John Gates;Gene Kauffman;George Smith
* [http://bama.edebris.com/download/tek/547/547.djvu Tektronix 547 Manual (DjVu)]
|series=500-series scopes
* [http://w140.com/tek_547.pdf Tektronix 547 Manual (PDF, 60MB)]
|manuals=
* [[Media:070-0398-00.pdf|Tektronix 547/RM547 Manual]] <small>070-0398-00, plus "547 Notes"</small> (OCR)
* [[Media:Tek_547_544_546_tech_instr_and_training.pdf|Tektronix 544/546/547 Technical Instruction and Training]] (OCR)
* [[Media:Tek 547 fcp.pdf|Tektronix 547 Factory Calibration Procedure]]
* [[Media:Tek 547 cal procedure.pdf]]
<small>
'''Alternate versions'''
* [https://bama.edebris.com/download/tek/547/547.djvu Tektronix 547 Manual] (DjVu @ BAMA)
* [[Media:070-0398-00 (2).pdf|Tektronix 547 Manual 070-0398-00]]
</small>
<small>
'''Modifications'''
* [[Media:Tek 547 mods.pdf|Tektronix 547 Modifications]]
* [[Media:050-0479-01.pdf|Disconnect Diode 547/R547 Serials 100-12479]] Tek Part [[050-0479-01]]
</small>
}}
}}
The '''Tektronix 547''' is a 50 MHz scope that takes [[letter-series and 1-series plug-ins]].   
The '''Tektronix 547''' is a 50 MHz scope that takes [[letter-series and 1-series plug-ins]].   
It has two identical timebases and,  
 
when used with the [[1A1]], [[1A2]], or [[1A4]],  
It has two identical timebases and, when used with the [[1A1]], [[1A2]], or [[1A4]],  
has the ability to display one input with one time scale and another input with a different time scale.   
has the ability to display one input with one time scale and another input with a different time scale.   
The effect is similar to a [[dual-beam scopes|dual-beam scope]]  
The effect is similar to a [[dual-beam scopes|dual-beam scope]]  
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There is also a rackmount version, the RM547 or R547.   
There is also a rackmount version, the RM547 or R547.   


The project lead for the development of the Tektronix [[544]], [[546]], and 547 was [[Bob Rullman]].
The program manager for the development of the Tektronix [[544]], [[546]], and 547 was [[Bob Rullman]].
The 547 vertical amplifier was designed by [[Keith Taylor]].
 
{{BeginSpecs}}
{{Spec | Bandwidth                | DC to 50 MHz (−3 dB) with fast plug-ins ([[1A1]], [[1A2]], [[1A4]], [[1A5]]) }}
{{Spec | Rise time                | 7 ns with [[1A1]] }}
{{Spec | Sweep Rates              | 100 ns/div to 5 s/div}}
{{Spec | External Horizontal Input | 100 mV/cm to 10 V/cm, DC to 400 kHz}}
{{Spec | CRT                      | [[T5470]] (154-0478-00 standard), 10 kV acceleration, 6x10 cm viewing area }}
{{Spec | Calibrator                | ~1 kHz, 200 μV<sub>p-p</sub> to 100 V<sub>p-p</sub> }}
{{Spec | Power                    | 90-136 V or 180-272 V, selected via primary voltage selector (inside cabinet) and voltage range selector (on rear panel), 50/60/400 Hz, 510 W, AC Fan }}
{{EndSpecs}}


==Internals==
==Internals==
===Triggering===
===Triggering===
Triggering is done with [[tunnel diodes]].
The 'A' and 'B' triggers are based on a 10 mA [[tunnel diodes|tunnel diode]].
The 'A' trigger is based on a 10 mA tunnel diode.
Up to serial number 11889, it uses a [[TD253]].
Up to serial number 11889, it uses a [[TD253]].
From 11890 onward, it uses a [[152-0140-01]].
From 11890 onward, it uses a [[152-0140-01]].


===CRT===
The 547 uses the Tektronix [[154-0478-00]] CRT.
===HV Transformer===
===HV Transformer===
A common problem with 547s is the [[HV transformers|HV transformer]].  
A common problem with 547s is the [[HV transformers|HV transformer]].  
Rather than potting the HV transformer in wax, as was done up to that point,  
Rather than potting the HV transformer in wax, as was done up to that point, the [[120-0308-00|547's HV transformer]] was potted in epoxy.
the 547's HV transformer was potted in epoxy.
Unfortunately, this epoxy turned out to absorb moisture over time, particularly when used in humid climates.
Unfortunately, this epoxy turned out to absorb moisture over time,  
particularly when used in humid climates.
The moisture causes increased losses in the transformer.  
The moisture causes increased losses in the transformer.  
Excessive losses require the regulator to drive the [[6AU5]] input oscillator tube (V800) harder.   
Excessive losses require the regulator to drive the [[6AU5]] input oscillator tube (V800) harder.   
Eventually, the drive circuit cannot supply enough power to keep the supply in regulation.
Eventually, the drive circuit cannot supply enough power to keep the supply in regulation.
The usual solution is to scavenge a replacement transformer from another scope.
The usual solution is to scavenge a replacement transformer from another scope.
As a labor of love, hobbyists have been known to rebuild the HV transformers.
As a labor of love, hobbyists have been known to rebuild the HV transformers.
This is discussed from time to time on the Yahoo TekScopes forum.
This is discussed from time to time on the groups.io (formerly Yahoo) TekScopes forum.
 
Bernie Schroder has found that the HV transformer degeneration can be slowed considerably by keeping the HV module cool and dry.
The mod he was taught by [[Jim Willams]] involves replacing the [[5642]] tube rectifiers with NTE517 diodes to reduce the load on the regulator circuit by about 1 Watt by eliminating the filaments.
However, this can force the regulator past its design limit and result in lack of regulation, until the transformer heats up and more power is required due to losses.
 
After changing to semiconductor diodes, it will be seen that grid pin 7 of V814 will be about 0 volts (fully on,
with no swing to regulate) in an attempt to force its anode (pin 6) to about +55 V, which is the screen input of the 6AU5 (pin 8).
 
One way to remedy this is to replace the anode resistor coming off pin 6 of V814 (R803) from 56 kΩ to 82 kΩ.
Doing so changes the grid voltage on pin 7 of V814 to a comfortable −0.8 V at switch-on.
 
Again, this becomes more negative as the losses inside the transformer increase, but not by much if the transformer is healthy.
 
A second path to thermal runaway on early serial numbers is C808, which resonates the transformer primary winding.  Tek used a Sprague 160P DiFilm Black Beauty.  In the 2020's, 160P's are exhibiting high Dissipation Factor when warm, enough to self-heat in this case.  Replace with any modern capacitor.


===Vertical Amplifier===
===Vertical Amplifier===
The 547 has a five-stage BJT vertical amplifier that is fully differential from the plug-in
The 547 has a five-stage BJT vertical amplifier that is fully differential from the plug-in connector to the CRT vertical deflection plates.  
connector to the CRT vertical deflection plates. There is one tube in the vertical signal path,
There is one tube in the vertical signal path, a [[12AT7]] acting as a unity-gain buffer between the plug-in connector and the vertical amplifier.
a [[12AT7]] acting as a unity-gain buffer between the plug-in connector and the vertical amplifier.
 
====Spoiler Switch====
The plug-in bay of the 547 has a "spoiler switch" that only enables the full bandwidth of the 547's vertical signal path
when certain relatively modern plug-ins are used, such as the [[1A1]], [[1A2]], [[1A4]], and [[1A5]].
 
Those plug-ins have a small hole to the left of the plug-in to mainframe connector, so they can be fully inserted without pressing the spoiler switch.
(Spectrum analyzer plug-in Types [[1L30]] and [[1L40]] have the hole too but for no reason since their vertical output is low frequency.)


* [[Media:Spoiler switch rationale from Tek 547 544 546 tech instr and training.pdf|Spoiler switch explanation excerpted from Tek 547 544 546 Technical Instruction and Training]]
* [[Media:Spoiler switch rationale from Tek 547 notes.pdf|Spoiler switch explanation excerpted from Tek 547 Notes]]
====Delay Line====
There is a 170 nanosecond [[delay line]] between the first and second gain stages.
There is a 170 nanosecond [[delay line]] between the first and second gain stages.


===Power Supply ===
===Power Supply ===


The 547's power supply provides regulated outputs of −150 V, +100 V, +225 V, +350 V, as well as a +325 V unregulated output for CRT HV section.
The 547's power supply provides regulated outputs of −150 V, +100 V, +225 V, and +350 V, plus a +325 V unregulated output for the CRT HV oscillator.


Multiple secondary windings feeds diodes for rectification for different voltages. Both center-tap and bridge configuration is used. Its a all Tube design for the regulation. There are multiple 6.3V secondary outputs for heaters, many elevated to different voltage levels based on the section/tube its used for to keep the Heater-Cathode voltage level within limits.
Multiple secondary windings feed diodes for rectification for different voltages, using both center-tap and bridge configurations.  
The regulator section uses no transistors, only tubes. There are multiple 6.3 V secondary outputs for heaters, some elevated to different voltage levels  
based on the section/tube that is supplied, in order to keep the heater-to-cathode voltage level within limits.


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 [[OG3]] VR tube. A [[12AX7]] is used as the comparator, two [[6CW5]] 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 +225 V and +100 V regulators employ a [[6080]] as the pass element, +350 uses a [[6CW5]].  
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 [[OG3]] VR tube.
A [[12AX7]] is used as the comparator and two [[6CW5]] in parallel are used as series pass tubes.
A [[6AU6]] is used as an error amplifier.  
Most other power supply sections in the 547 replicate the same basic design, except slight changes in tubes used:
The +225 V and +100 V regulators employ a [[6080]] as the pass element, and +350 uses a [[6CW5]].  


The plate voltage delay circuit is as like in may other Teks, uses a 6N030 delay tube (P/N 148-0021-00) to control a relay that switches plate supply voltages on only after the tubes are warmed up. Heater voltage is directly applied to tubes on Power on.  
The plate voltage delay circuit is similar to that found in many may other Tek scopes of the same era.  
Heater voltage is applied to all tubes immediately when the power switch is turned on.
A [[6N030T|6N030T delay tube (P/N 148-0021-00)]] controls a relay that switches plate supply voltages on only after the tubes are warmed up.


==Links==
==Links==
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* [http://www.ebay.com/gds/The-Tektronix-547-Oscilloscope-Magic-in-the-Box-/10000000000725321/g.html The Tektronix 547 Oscilloscope - Magic in the Box]
* [http://www.ebay.com/gds/The-Tektronix-547-Oscilloscope-Magic-in-the-Box-/10000000000725321/g.html The Tektronix 547 Oscilloscope - Magic in the Box]
* [http://www.thevalvepage.com/testeq/tek/547/547.htm J.Evans's 547 page]
* [http://www.thevalvepage.com/testeq/tek/547/547.htm J.Evans's 547 page]
==Common Problems==
* See [[547/Repairs]]


==Pictures==
==Pictures==
===547===
<gallery>
<gallery>
Tek 547 1a2 new.jpg
Tek 547 trace.jpg | 547 with [[1A2]]
Tek 547 1a2 new.jpg|547 with [[1A2]]
Tek 547.jpg|Front view
Tek 547.jpg|Front view
547_01.JPG|Top
Tek 547 eng.jpg|547 serial "ENG B 23"
547_02.JPG|Right
Tek 547 eng2.jpg|547 serial "ENG B 23"
547_03.JPG|Left
Tek-547 vert amp2.png|Vertical amplifier
Tek-547-trigger a.png|Trigger A
Tek rm547.jpg|RM547
Tek 547 ampex front.jpg
Tek 547 ampex front.jpg
Tek 547 ampex right internal.jpg
Tek_547_Delayed_Trigger1.JPG | Tek 547 Delayed Trigger & ALT Sweep
Tek 547 ampex left internal.jpg
Tek_547_Delayed_Trigger2.jpg | Tek 547 Delayed Trigger & ALT Sweep
Tek 547 trace two sine.jpg|547 trace
Tek 547 1a1 front.jpg|547 with [[1A1]]
Tek_547_4-Trace.jpg | 547 with 1A2 in ALT Sweep Mode
Tek_547_Delayed_Trig.jpg | 547 Delayed Trace
Tek 547 ampex right external.jpg
Tek 547 ampex right external.jpg
Tek 547 ampex rear.jpg
Tek 547 ampex rear.jpg
Grey face 547.jpg|Gray 547
Grey face 547.jpg|Gray 547
Tek rm547 trace.jpg
Tektronix rm547.jpg
Tek 547 rear close.jpg
Tek 547 rear close.jpg
Tek 547 eng.jpg|547 serial "ENG B 23"
Tek 547 eng2.jpg|547 serial "ENG B 23"
Tek 547 rear connections.jpg|rear connections
Tek 547 rear connections.jpg|rear connections
Tek_547_Vert_Amp.jpg | Tek 547 Vertical Amplifier  
</gallery>
===547 Internals===
<gallery>
Tek_547-Top.jpeg | Internals - Top
Tek_547-RHS-TBOpen.jpeg | Internals - RHS
Tek_547-RHS.jpeg | Internals - Time Base - RHS
Tek_547-Internal-LHS.jpeg | Internals - LHS
Tek_547-Internal-Bottom.jpeg | Internals - Bottom
Tek_547_HVSection-NoCover.jpg | Tek 547 HV Section and [[5642]]HV Rectifier Tube (Cover removed)
Tek_547_HV_Diodes.jpg | Solid State HV Diode Mod
Tek_547-TunnelDiodes-Trigger.jpg | Tunnel Diodes TD253 and TD3A in a Tek 547 Trigger/ Sweep Section
Tunnel_DIode_1D2_2.2mA.jpg | 2.2 mA Tunnel Diode in 547 Delay Pickoff
Tek_547_Vert_Amp.jpg | Tek 547 Vertical Amplifier. The output transistors are mounted on [[beryllium oxide]] discs.
547_01.JPG|Top
547_02.JPG|Right
547_03.JPG|Left
Tek_547_CRT1.jpg | Tek 547 CRT
Tek_547_CRT1.jpg | Tek 547 CRT
Tek_547_CRT2.jpg | Tek 547 CRT Side View
Tek_547_CRT2.jpg | Tek 547 CRT Side View
Tek_547_CRT_Def_Plates1.jpg | Tek 547 CRT Deflection Plates & Assembly
Tek_547_CRT_Def_Plates1.jpg | Tek 547 CRT Deflection Plates & Assembly
Tek_547_CRT_Def_Plates2.jpg | Tek 547 CRT Electron Gun Assembly
Tek_547_CRT_Def_Plates2.jpg | Tek 547 CRT Electron Gun Assembly
Tek_547_UnderChassis-No-Transformer.jpg | Tek 547 Underside of Chassis. Main Transformer is Not Present.
Tek_547_Chassis_Without_CRT.jpg | Tek 547 Chassis Without CRT and Plug in
Tek_547_Chassis_Without_CRT.jpg | Tek 547 Chassis Without CRT and Plug in
Tek_547_Screen.jpg |  Tek 547 Screen Scale  
Tek_547_Screen.jpg |  Tek 547 Screen Scale
Tek_547_Top.jpg | Tek 547 Top
Tek_547_HVSection-NoCover.jpg | Tek 547 HV Section and [[5642]]HV Rectifier Tube (Cover removed)
Tek_547_Power-Transformer3.jpg  | Tek 547 Main Transformer
Tek_547_Power-Transformer3.jpg  | Tek 547 Main Transformer
Tek_547_Power-Transformer2.jpg  | Tek 547 Main Transformer
Tek_547_Power-Transformer2.jpg  | Tek 547 Main Transformer
Tek_547_Power-Transformer1.jpg  | Tek 547 Main Transformer
Tek_547_Power-Transformer1.jpg  | Tek 547 Main Transformer
Tek_547_Tubes.jpg | Tek 547 Inside view with Power ON
Tek_547_Tubes.jpg | Tek 547 Inside view with Power ON
Tek_547-TunnelDiodes-Trigger.jpg | Tunnel Diodes TD253 and TD3A in a Tek 547 Trigger and Sweep Section
Tek_547_4-Trace.jpg | 547 with 1A2 in ALT Sweep Mode
Tek_547_Delayed_Trig.jpg | 547 Delayed Trace
Tek_547_Transformer.jpg | 547 LV Transformer Connections
Tek_547_Transformer.jpg | 547 LV Transformer Connections
Tunnel_DIode_1D2_2.2mA.jpg | 2.2 mA Tunnel Diode in 547 Delay Pickoff
Tek_547_Inside_Tubes.jpg | Inside a Tek 547
Tek_547_Inside_Tubes.jpg | Inside a Tek 547
Tek_547_Delayed_Trigger1.JPG | Tek 547 Delayed Trigger & ALT Sweep
Tek 547 ampex right internal.jpg
Tek_547_Delayed_Trigger2.jpg | Tek 547 Delayed Trigger & ALT Sweep
Tek 547 ampex left internal.jpg
</gallery>
 
=== RM 547===
<gallery>
Tek rm547.jpg|RM547
Tek rm547 trace.jpg
Tektronix rm547.jpg
</gallery>
 
=== Schematics ===
<gallery>
Tek-547-trigger a.png|Trigger A
Tek-547 vert amp2.png|Vertical amplifier
</gallery>
</gallery>
==Components==
{{Parts|547}}


[[Category:500 series scopes]]
[[Category:500 series scopes]]
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