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556 (view source)

Revision as of 03:17, 8 February 2015

296 bytes added ,  8 February 2015
6 trace screen shot
(6 trace screen shot)
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introduced=1966 |
introduced=1966 |
discontinued=(?) |
discontinued=(?) |
manuals=
manuals=
* [http://bama.edebris.com/download/tek/556/tek%20556.pdf Tektronix 556 Manual (PDF)]
* [http://bama.edebris.com/download/tek/556/tek%20556.pdf Tektronix 556 Manual (PDF)]
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}}


The Tektronix 556 is a [[dual-beam scopes|dual-beam scope]], the successor to the Tektronix [[555]]. It uses [[letter-series and 1-series plug-ins]]. A rack-mount version, the RM556 also exists. The 556, which is wider than the average 500-series scope, fits in the [[205]] cart.
The Tektronix 556 is a [[dual-beam scopes|dual-beam scope]], the successor to the Tektronix [[555]]. It uses [[letter-series and 1-series plug-ins]]. A rack-mount version, the RM556, also exists. The 556, which is wider than the average 500-series scope, fits in the [[205]] cart.


== Dual-Beam Modes ==
== Dual-Beam Modes ==
The 556 is a true dual-beam scope and none of the signal path is shared between the two beams.  Electrically speaking, the power supply and the calibrator are the only parts that are common to both beams.  The 556 has almost complete left-right symmetry, corresponding to upper and lower beams.  Although the beams can be operated completely independently, the 556 provides many options for routing signals between the vertical plug-ins, triggers, sweeps, horizontal and vertical amplifiers.  For example, a common use for a 556 is to view two simultaneous single-shot events, both sweeps being triggered by one of the traces.  For this purpose, the 556 allows the output of one sweep generator to be routed to the horizontal amplifier of the other beam, so it drives both beams.  Many other more sophisticated modes are also available.
The 556 is a true dual-beam scope and none of the signal path is shared between the two beams.  Electrically speaking, the power supply and the calibrator are the only parts that are common to both beams.  The 556 has almost complete left-right symmetry, corresponding to upper and lower beams.  Although the beams can be operated completely independently, the 556 provides many options for routing signals between the vertical plug-ins, triggers, sweeps, horizontal and vertical amplifiers.  For example, a common use for a 556 is to view two simultaneous single-shot events, both sweeps being triggered by one of the traces.  For this purpose, the 556 allows the output of one sweep generator to be routed to the horizontal amplifier of the other beam, so it drives both beams.  Many other more sophisticated modes are also available.


== Triggering ==
==Comparison with other scopes==
The triggering in the 556 is done using [[tunnel diodes]]
=== Tektronix 555 ===
and the trigger circuit sits on its own small PC board
The 556 is a one-piece unit whereas the [[555]] has a the power supply in a separate box.
just behind the trigger source selection switch. 
Triggering and sweep circuitry is integrated into the 556 mainframe, as opposed to  
 
== Vertical Amplifiers ==
The vertical amplifier of the 556 is solid state except for the input cathode followers ([[12AT7]]) and and the
output stage ([[8608]]). 
 
== CRT Circuit ==
The CRT circuit of the 556 uses two HV transformers.
The lower beam transformer, T1301, produces:
* CRT anode voltage: +8150V
* lower beam cathode voltage: -1850V
* lower beam control grid (blanking) voltage: varies, about -2000V
 
The upper beam transformer, T1351, produces:
* upper beam cathode voltage: -1850V
* upper beam control grid (blanking) voltage: varies, about -2000V
 
== Comparison with the 555 ==
The 556 is a one-piece unit whereas the 555 has a the power supply in a separate box.
Triggering and sweep circuitry  
is integrated into the 556 mainframe, as opposed to  
the removable timing units in the 555.  The 556 takes  
the removable timing units in the 555.  The 556 takes  
two [[letter-series and 1-series plug-ins|letter-series or 1-series vertical plug-ins]].
two [[letter-series and 1-series plug-ins|letter-series or 1-series vertical plug-ins]].
The 556's bandwidth is 50MHz, whereas the 555's is 30.
The 556's bandwidth is 50 MHz, whereas the 555's is 30.


The 555 and 556 both use separate HV transformers for the lower beam and upper beam voltages.
The 555 and 556 both use separate HV transformers for the lower beam and upper beam voltages.
In both models, the lower beam HV transformer produces the CRT anode voltage.
In both models, the lower beam HV transformer produces the CRT anode voltage.


== Comparison with the 565 ==
=== Tektronix 565 ===
The 556 superficially resembles the [[565]],  
The 556 superficially resembles the [[565]],  
which is is also a dual-beam one-piece scope, but the 565 takes two
which is is also a dual-beam one-piece scope, but the 565 takes two
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Also, the 565 uses a single HV transformer to produce all CRT voltages,  
Also, the 565 uses a single HV transformer to produce all CRT voltages,  
whereas the 556 uses two transformers.
whereas the 556 uses two transformers.
==Internals==
===Triggering ===
The triggering in the 556 is done using [[tunnel diodes]]
and the trigger circuit sits on its own small PC board
just behind the trigger source selection switch. 
===Vertical Amplifiers ===
The vertical amplifier of the 556 is solid state except for the input cathode followers ([[12AT7]]) and and the
output stage ([[8608]]). 
===CRT Circuit ===
The CRT circuit of the 556 uses two HV transformers.
The lower beam transformer, T1301, produces:
* CRT anode voltage: +8150 V
* lower beam cathode voltage: -1850 V
* lower beam control grid (blanking) voltage: varies, about -2000 V
The upper beam transformer, T1351, produces:
* upper beam cathode voltage: -1850 V
* upper beam control grid (blanking) voltage: varies, about -2000 V


==Pictures==
==Pictures==


<gallery>
<gallery>
Image:556_front.JPG|Front panel of a 556.
File:556_front.JPG | Front panel of a 556
Image:Rm556.jpg|Front view of an RM556.
File:Rm556.jpg | Front view of an RM556
Image:Rm556 trigboard.jpg|Trigger board contains two tunnel diodes and a reed relay.
File:Wellenkino 556.jpg
Image:556-top.JPG|Top view.
File:Tek 556 rear.jpg | Rear view
Image:Rm556 top2.jpg|Top view of RM556.
File:Tek556-LT-AppNote49.jpg | 556 screen shot showing a total of six traces, two on one timebase and four on the other. From Jim Williams, Linear Technology Application Note #49
Image:556-right.JPG|Right side view.
</gallery>
Image:556_bottom.JPG|Bottom view.
===Internal===
Image:556_bottom2.JPG|Bottom view with power supply/calibrator/delay pickoff chassis swung out.
<gallery>
Image:Rm556 output amp.jpg|Output amplifier driving deflection plates.
File:Rm556 trigboard.jpg | Trigger board contains two tunnel diodes and a reed relay
Image:556_tube1.jpg|Neck of 556 CRT.  The tube contains two electrically independent guns and vertical and horizontal deflection plates.
File:556-top.JPG | Top view
Image:Tek 556 rear.jpg|Rear view
File:Rm556 top2.jpg | Top view of RM556
File:556-right.JPG | Right side view
File:556_bottom.JPG | Bottom view
File:556_bottom2.JPG | Bottom view with power supply/calibrator/delay pickoff chassis swung out
File:Rm556 output amp.jpg | Output amplifier driving deflection plates
File:556_tube1.jpg | Neck of 556 CRT - the tube contains two electrically independent guns and vertical and horizontal deflection plates
</gallery>
===Schematics===
<gallery>
File:Tek 556 vert.png|Vertical amp schematic
File:Tek 556 vert.png|Vertical amp schematic
File:Tek 556 hvps.png|CRT Circuit
File:Tek 556 hvps.png|CRT Circuit
File:Wellenkino 556.jpg
</gallery>
</gallery>


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