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Revision as of 18:28, 16 December 2018

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title=Tektronix 661 |
title=Tektronix 661 |
summary=Sampling scope |
summary=Sampling scope |
image=661_front.jpg |
image=661_5T1A_4S1_front.JPG |
caption=Tektronix 661 |
caption=Tektronix 661 |
introduced=1961 |
introduced=1961 |
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The other cable sends the "start sample signal" from the timing unit to the sampling unit, telling it when to sample.   
The other cable sends the "start sample signal" from the timing unit to the sampling unit, telling it when to sample.   


The connectors used for the inter-module coaxial connections were made by Gremar. The connector on the plug-in side  
The connectors used for the inter-module coaxial connections were made by Gremar.  
is a [[Gremar connector|Gremar 8212A]]. The connector on the scope side is a Gremar 8205A.
The connector on the plug-in side is a [[Gremar connector|Gremar 8212A]].  
When operating one or both of the plug-ins outside of the 661, the sampling unit still
The connector on the scope side is a Gremar 8205A.  
needs the sampling pulse from the timing unit. The Gremar extension cable, part number 012-070 (shown below) enables that.
When operating one or both of the plug-ins outside of the 661,
the timing unit can be fed an external trigger signal via the timing unit's front panel.
However, the sampling unit still needs the start sample signal from the timing unit.
The Gremar extension cable, part number 012-070 (shown below) enables that.


== Triggering modes ==
== Triggering modes ==
A 661 can be triggered in at least four distinct modes:
A 661 can be triggered in at least four distinct modes:
* The 4S1 uses a trigger pickoff transformer to produce the internal trigger signal that can trigger the timing unit. The 4S1 is the only 661 sampling unit that produces an internal trigger signal.
* The 4S1 uses a trigger pickoff transformer to produce the internal trigger signal that can trigger the timing unit. The 4S1 is the only 661 sampling unit that produces an internal trigger signal.
* An external trigger signal can be fed to the timing unit via its front panel.   
* An external trigger signal can be fed to the timing unit via its front panel.   
* The timing unit can be operated in in free-running mode and the resulting pulse signal can be the stimulus for the device under test.  This mode is similar to a TDR.
* The timing unit can be operated in in free-running mode and the resulting pulse signal can be the stimulus for the device under test.  This mode is similar to a TDR.
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=== Power Supply ===
=== Power Supply ===
The power supply is typical of Tektronix scopes of early 1960s. An [[OG3]] tube is used as a voltage reference for the +300 V supply.
The power supply is typical of Tektronix scopes of early 1960s.
The other supply voltages use the +300 V supply as their reference. The +19 V and -19 V supplies use BJT-based regulators.   
It is linear.
All power rectifiers are silicon diodes.
An [[OG3]] tube is used as a voltage reference for the +300 V supply.
The other supply voltages use the +300 V supply as their reference.
The +19 V and -19 V supplies use BJT-based regulators.   
The other regulators are tube-based.
The other regulators are tube-based.
A 45 second delay tube is used so that plate voltage isn't applied to any tube in the 661
until the cathodes are hot.
The 661 has a 137°F/58 °C [[thermal cutoff]].
In practice, it doesn't run hot.


=== Indicator ===
=== Indicator ===
The indicator is a conventional X-Y indicator. The total CRT accelerating voltage is 3 kV and the vertical and horizontal amplifiers are  
The indicator is a conventional X-Y indicator.
relatively mild differential amplifiers made of [[6DJ8]] tubes and [[OC170]] germanium bipolar junction transistors.  
The total CRT accelerating voltage is 3 kV.
The 661 uses a [[T5030]] CRT with P2 [[phosphor]].
The vertical and horizontal amplifiers are essentially the same,
each consisting of a two-stage differential amplifier.
The first differential stage is made of a pair of [[OC170]] germanium PNP bipolar junction transistors
driven single-endedly with emitters connected directly together (maximum voltage gain).
The second differential stage is made of both triodes of a [[6DJ8]] tube with cathodes connected directly together (maximum voltage gain).  
The vertical and horizontal amplifiers have feedback loops around them that determine their gain.
The vertical and horizontal amplifiers have feedback loops around them that determine their gain.
The 661 uses a [[T5030]] CRT with P2 [[phosphor]].


=== Calibrator ===
=== Calibrator ===
The amplitude/time calibrator is a Colpitts oscillator that uses a [[7119]] tube. It produces clippped sine waves at frequencies
The amplitude/time calibrator is a Colpitts oscillator that uses a [[7119]] tube.
from 100 kHz to 100 MHz and amplitudes from 1 mV to 1 V. The output is 50 Ω [[GR-874 connector]].
It produces clippped sine waves at frequencies
The signal from the calibration generator is available on the front panel and is also sent to the timing generator through the multi-pin plug-in connector.   
from 100 kHz to 100 MHz and amplitudes from 1 mV to 1 V.
The output is 50 Ω [[GR-874 connector]].
The signal from the calibration generator is available on the front panel
and is also sent to the timing generator through the multi-pin plug-in connector.   
This allows the timing plug-ins to select "CAL" as a trigger source.   
This allows the timing plug-ins to select "CAL" as a trigger source.   
In this mode, the calibration generator can be used as the stimulus for the device under test.   
In this mode, the calibration generator can be used as the stimulus for the device under test.   
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with a risetime of about 150 ps and a pulse width of about 400 ns.
with a risetime of about 150 ps and a pulse width of about 400 ns.
The output is a 50 Ω [[GR-874 connector]].
The output is a 50 Ω [[GR-874 connector]].
When a timing unit (e.g., a 5T1) triggers, it sends a pulse through pin 10 of the J4 interconnect to the delayed pulse generator, which regenerates the pulse.
When a timing unit (e.g., a 5T1) triggers, it sends a pulse through pin 10 of the J4 interconnect
to the delayed pulse generator, which regenerates the pulse.
There are three versions of the 661 delayed pulse generator (serial numbers 101 through 2829,  2830 through 3459, 3460 and up).
There are three versions of the 661 delayed pulse generator (serial numbers 101 through 2829,  2830 through 3459, 3460 and up).
All three versions use a 50 mA, 6 pF germanium tunnel diode to generate the actual output pulse.
All three versions use a 50 mA, 6 pF germanium tunnel diode to generate the actual output pulse.
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and mainframe wiring harness for routing trigger and timing signals between the two units?''
and mainframe wiring harness for routing trigger and timing signals between the two units?''


Some 661s have a 41 pin [[Bendix connector]], J5, on the rear panel, perhaps to allow the 661 to be interfaced to low speed data acquisition equipment or a computer.
Some 661s have a 41 pin [[Bendix connector]], J5, on the rear panel,
perhaps to allow the 661 to be interfaced to low speed data acquisition equipment or a computer.
This is essentially a pass-through from J2 & J3, the secondary multi-pin connectors on the vertical & horizontal plug-ins.
This is essentially a pass-through from J2 & J3, the secondary multi-pin connectors on the vertical & horizontal plug-ins.
These connectors carry switch position information (number, magnitude & units) and clock & gate pulses.
These connectors carry switch position information (number, magnitude & units) and clock & gate pulses.
Not all plug-ins had this 2nd connector; the [[5T1A]] does, while the [[5T3]] does not.   
Not all plug-ins had this 2nd connector; the [[5T1A]] does, while the [[5T3]] does not.   
The 661 has a 137°F/58 °C [[thermal cutoff]].  In practice, it doesn't run hot.


The Tektronix [[012-064]] is a plug-in extension cable for the 661.
The Tektronix [[012-064]] is a plug-in extension cable for the 661.
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{{MissingSpecs}}
{{MissingSpecs}}


== Mechanical ==
The 661 is constructed similarly to late-model [[500-series scopes]].
The chassis is made of sheet aluminum.
Most wiring is on [[Ceramic_Strips|ceramic strips]].
The side panels come off like those of a [[545|545B]] or [[547]].
The plug-ins of a 661 are incompatible with any other Tek scope,
but the construction style is similar.
The 661, like the 500-series scopes, uses Amphenol 26-series connectors
for the electrical interface between plug-in and mainframe.
The sides and rear of the 661 painted identically to late-model
500-series scopes, i.e., Tek-blue wrinkle.
==Links==
==Links==


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<gallery>
<gallery>
661 5T1A 4S1 front.JPG  | front view
661_front.jpg | front view
661_top_int.jpg | top internal view
661_top_int.jpg | top internal view
661_front.jpg | front view
Tek 661 block.png|Block Diagram
661_trace.jpg | trace with 10 samples/cm and 2× horizontal expansion
661_trace.jpg | trace with 10 samples/cm and 2× horizontal expansion
661_left_int.jpg | lleft internal view
661_left_int.jpg | lleft internal view
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Tek 661 rear2.jpg|Rear panel of 661. J5 connector is on the upper left
Tek 661 rear2.jpg|Rear panel of 661. J5 connector is on the upper left
Tek 661 rear J5 connector.jpg|J5 connector on rear panel of 661
Tek 661 rear J5 connector.jpg|J5 connector on rear panel of 661
Tek 661 late sn delayed pulse2.png|Delayed pulse generator, final circuit version
</gallery>
</gallery>


[[Category:Sampling scopes]]
[[Category:Sampling scopes]]
[[Category:661 series scopes]]
[[Category:661 series scopes]]
Retrieved from "https://w140.com/tekwiki/wiki/Special:MobileDiff/28511...40479"

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