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{{Oscilloscope Sidebar | | {{Oscilloscope Sidebar | ||
|manufacturer=Tektronix | |||
summary=Sampling scope | | |series= | ||
image= | |model=661 | ||
caption=Tektronix 661 | | |summary=Sampling scope | ||
introduced=1961 | | |image=661_5T1A_4S1_front.JPG | ||
discontinued=(?) | | |caption=Tektronix 661 | ||
manuals= | |introduced=1961 | ||
* [ | |discontinued=(?) | ||
* [ | |designers=Norm Winningstad,Chuck Edgar,George Frye | ||
* [ | |manuals= | ||
* [http:// | * [[Media:070-324.pdf|Tektronix 661 Manual 070-324]] (early) | ||
* [ | * [[Media:070-0324-01.pdf|Tektronix 661 Manual 070-0324-01]] (late) | ||
* [[Media:tek_661_4s1_5t1_preliminary.pdf|Tek 661 4S1 5T1 Preliminary Manual]] | |||
* [ | <small> | ||
'''Alternate copies''' | |||
* [http://bama.edebris.com/manuals/tek/661 Tektronix 661 @ BAMA] | |||
* [ | |||
* [ | '''Calibration''' | ||
* [[Media:tek_661_factory_cal_proc.pdf|Tektronix 661 Factory Calibration Procedure]] | |||
* [[Media:Tek 661 cal outline.pdf|Tektronix 661 Calibration Outline]] (PDF, OCR)]] | |||
'''Other''' | |||
* [[Media:Nucl_Instrum_Methods_TD_Induct_effects_1968.pdf|Inductance Effects on Capacitive Loading of a Tunnel Diode]] | |||
* [[Media:Ragsdale_661_1963.pdf|Self-Sampling System for Measurement of Picosecond Pulse Characteristics]], R.Ragsdale, 1963 | |||
</small> | |||
}} | }} | ||
The '''Tektronix 661''' is a [[sampling oscilloscope]] that was [[introduced in 1961]]. | The '''Tektronix 661''' is a [[sampling oscilloscope]] that was [[introduced in 1961]]. | ||
It accepts two plug-ins, a sampling unit and a timing unit. | It accepts two plug-ins, a sampling unit and a timing unit. | ||
{{MissingSpecs}} | |||
==History== | |||
The 661 project was led by [[Norm Winningstad]]. | |||
In "Winning with People: The First 40 Years of Tektronix", Marshall Lee writes: | |||
<blockquote> | |||
During the early stages of the transition from tubes to transistors, | |||
however, computer research focused on emitter-coupled logic circuits, or ECL circuits, | |||
which proved much faster than conventional circuits, but also demanded higher-speed measuring instruments, | |||
which meant a much wider bandwidth. | |||
In response to ECL research, by 1962 Winningstad's group had produced the Type 661 sampling oscilloscope, | |||
which provided the answer to high speed and screen resolution. | |||
</blockquote> | |||
In addition to Winningstad, [[Chuck Edgar]] and [[George Frye]] worked on the 661 design. | |||
==Plug-ins== | |||
Four sampling units were made: | Four sampling units were made: | ||
* [[4S1]] (0.35 ns rise time) | * [[4S1]] (0.35 ns rise time) | ||
* [[4S2 | * [[4S2]] (0.1 ns rise time) | ||
* [[4S2A]] (90 ps rise time) | |||
* [[4S3]] (uses [[P6038]] sampling probes) | * [[4S3]] (uses [[P6038]] sampling probes) | ||
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* [[5T1A]] | * [[5T1A]] | ||
* [[5T3]] | * [[5T3]] | ||
There is also a set of calibration fixtures, [[067-0066-00]], consisting of one Vertical Test Load Unit and one Sweep Test Load Unit plug-in, but these were likely internal-only products for use in production and service as the 067-0066-00 manual says that ''067-0066-00 Test Load Units are not required for calibration of 661s in the field''. | |||
== Inter-module signals == | == Inter-module signals == | ||
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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 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 | 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 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. | The power supply is typical of Tektronix scopes of early 1960s. | ||
The other supply voltages use the +300 V supply as their reference. | 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 indicator is a conventional X-Y indicator. | ||
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. | ||
=== Calibrator === | === Calibrator === | ||
The amplitude/time calibrator is a Colpitts oscillator that uses a [[7119]] tube. | 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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=== Delayed Pulse Generator === | === Delayed Pulse Generator === | ||
The delayed pulse generator is a [[tunnel diodes|tunnel diode]] circuit that produces a negative-going 250 mV pulse with a risetime of about 150 ps and a pulse width of about 400 ns. | The delayed pulse generator is a [[tunnel diodes|tunnel diode]] circuit that produces a negative-going 250 mV 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. | with a risetime of about 150 ps and a pulse width of about 400 ns. | ||
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. | |||
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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Based on the available schematics, the 661 appears to have been designed in 1961. | Based on the available schematics, the 661 appears to have been designed in 1961. | ||
:''During what years was it manufactured?'' | :''During what years was it manufactured?'' | ||
:''Why is it that the 661 has a dedicated high-speed coaxial interface between the sampling unit the timing unit while later 560-series sampling systems ([[3S2]], [[3T77A]], etc.) simply use the regular plug-in connector and mainframe wiring harness for routing trigger and timing signals between the two units?'' | :''Why is it that the 661 has a dedicated high-speed coaxial interface between the sampling unit the timing unit | ||
while later 560-series sampling systems ([[3S2]], [[3T77A]], etc.) simply use the regular plug-in connector | |||
and mainframe wiring harness for routing trigger and timing signals between the two units?'' | |||
Some 661s have a 41 pin [[Bendix connector]] 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, Tek part number 131-212, 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. | |||
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. | |||
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. | ||
== 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, but the | |||
661 uses a 24-pin version whereas the 500-series uses a 16-pin version | |||
of the connector. | |||
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> | ||
Tek 661 s-52 rise.jpg|661 with [[4S1]] and [[5T3]] fed by [[S-52]]. 2 ns/div with 10x horizontal expansion gives 200 ps/div. | |||
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 | ||
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 | |||
Tek 661 ad 1963.png|Ad from 1963 | |||
</gallery> | </gallery> | ||
{{Plugins|661}} | |||
==Components== | |||
{{Parts|661}} | |||
[[Category:Sampling scopes]] | [[Category:Sampling scopes]] | ||
[[Category:661 series scopes]] | [[Category:661 series scopes]] |