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* http://w140.com/ragsdale_661_1963.pdf | * http://w140.com/ragsdale_661_1963.pdf | ||
}} | }} | ||
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 | It accepts two plug-ins, a sampling unit and a timing unit. | ||
Four sampling units were made: | Four sampling units were made: | ||
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* [[5T3]] | * [[5T3]] | ||
== Inter-module | == Inter-module signals == | ||
The timing units use [[tunnel diodes|tunnel diode]] triggering. | The timing units use [[tunnel diodes|tunnel diode]] triggering. | ||
Two | Two 50 Ω coaxial cables in the scope connect the sampling unit to the timing unit. | ||
One of these cables sends the "internal trigger signal" from the sampling unit to the timing unit. | One of these cables sends the "internal trigger signal" from the sampling unit to the timing unit. | ||
The other cable sends the "start sample signal" from the timing unit to the sampling unit, | The other cable sends the "start sample signal" from the timing unit to the sampling unit, telling it when to sample. | ||
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. The connector on the plug-in side | ||
is a Gremar 8212A. | is a [[Gremar connector|Gremar 8212A]]. The connector on the scope side is a Gremar 8205A. | ||
When operating one or both of the plug-ins outside of the 661, the sampling unit still | When operating one or both of the plug-ins outside of the 661, the sampling unit still | ||
needs the sampling pulse from the timing unit. The Gremar extension cable, | needs the sampling pulse from the timing unit. The Gremar extension cable, part number 012-070 (shown below) enables that. | ||
part number 012-070 (shown below) enables that. | |||
== Triggering | == 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. | ||
Line 60: | Line 59: | ||
=== Power Supply === | === Power Supply === | ||
The power supply is typical of | 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. | ||
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. | ||
An [[OG3]] tube is used as a | The other regulators are tube-based. | ||
voltage reference for the + | |||
The other supply voltages use the + | |||
supply as their reference. The + | |||
use BJT-based regulators. The other regulators are tube-based. | |||
=== 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 and the vertical and horizontal amplifiers are | ||
The total CRT accelerating voltage is | relatively mild differential amplifiers made of [[6DJ8]] tubes and [[OC170]] germanium bipolar junction transistors. | ||
the vertical and horizontal amplifiers are | The vertical and horizontal amplifiers have feedback loops around them that determine their gain. | ||
relatively mild differential amplifiers made of [[6DJ8]] tubes | |||
and [[OC170]] germanium bipolar junction transistors. | |||
The vertical and horizontal amplifiers have feedback loops around them | |||
that determine their gain. | |||
The 661 uses a [[T5030]] CRT with P2 [[phosphor]]. | The 661 uses a [[T5030]] CRT with P2 [[phosphor]]. | ||
=== Calibrator === | === Calibrator === | ||
The amplitude/time calibrator is a Colpitts oscillator that uses a [[7119]] | The amplitude/time calibrator is a Colpitts oscillator that uses a [[7119]] tube. It produces clippped sine waves at frequencies | ||
tube. It produces clippped sine waves at frequencies from | from 100 kHz to 100 MHz and amplitudes from 1 mV to 1 V. The output is 50 Ω [[GR-874 connector]]. | ||
amplitudes from | 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. | ||
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 | 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 output is a 50 Ω [[GR-874 connector]]. | ||
a [[tunnel diodes|tunnel diode]] circuit | 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. | ||
that produces a negative-going | There are three versions of the 661 delayed pulse generator (serial numbers 101 through 2829, 2830 through 3459, 3460 and up). | ||
with a risetime of about 150 ps | All three versions use a 50 mA, 6 pF germanium tunnel diode to generate the actual output pulse. | ||
and a pulse width of about 400 ns. | In early 661 production, a [[1N3130]] tunnel diode was used. Then it was replaced by a [[TD1081]]. | ||
The output is | The circuit versions also differ in how they bias and trip the output tunnel diode. | ||
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 | |||
All three versions use a | |||
to generate the actual output pulse. | |||
In early 661 production, a [[1N3130]] tunnel diode was used. | |||
Then it was replaced by a [[TD1081]]. | |||
The circuit versions also differ in how they | |||
bias and trip the output tunnel diode. | |||
Based on the available schematics, | Based on the available schematics, the 661 appears to have been designed in 1961. | ||
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. 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. | 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. 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 661 has a 137°F [[thermal cutoff]]. | The 661 has a 137°F [[thermal cutoff]]. In practice, it doesn't run hot. | ||
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. | ||
{{MissingSpecs}} | |||
==Links== | ==Links== | ||
* [http://readingjimwilliams.blogspot.com/2013/06/scope-sunday-45.html Reading Jim Williams: Scope Sunday #45] | * [http://readingjimwilliams.blogspot.com/2013/06/scope-sunday-45.html Reading Jim Williams: Scope Sunday #45] | ||
* A 661 can be seen in the [https://www.youtube.com/watch?v=I9m2w4DgeVk Tektronix film on Transmission Lines]. | |||
==Pictures== | ==Pictures== | ||
<gallery> | <gallery> | ||
661_top_int.jpg | top internal view | |||
661_front.jpg | front view | |||
661_trace.jpg | trace with 10 samples/cm and 2× horizontal expansion | |||
661_left_int.jpg | lleft internal view | |||
661_rt_int.jpg | right internal view | |||
Tek_661_rear.jpg | rear view (fan removed) | |||
Tek_661_solder.jpg | close-up of solder & inspection markings | |||
4s1_top.jpg|top view of 4S1 | |||
4s1_timing_pulse_connection.jpg | Coaxial interconnect from timing plug-in goes through the mainframe, into the 4S1, and ends here, at the sampler. | |||
4s1_sampling_bridge.jpg | This is the sampler. The GaAs sampling diodes are arranged in a diamond shape and are directly connected to the socket from the delay line. | |||
4s1_delay_connection.jpg | The delay line is a coil of coax going from the trigger pickoff to the sampler. | |||
661_timing_interconnect.jpg | The 661 mainframe has two pieces of 50 Ω coax that connect the sampling unit bay to the timing unit bay. The plug-ins engage with these interconnects when inserted. | |||
4s2_4.jpg | 4S2 top view | |||
4s2_3.jpg | 4S2 front view | |||
Tek 661 extension.JPG | [[012-064]] plug-in extension cable for 661 | |||
Tek_gremar_extension_012-070.jpg | [[012-070]] Gremar Extension Cable | |||
Tek 661 d992 mod.png | Mod described in June 1963 Service Scope regarding the delayed pulse generator | |||
</gallery> | </gallery> | ||
[[Category:Sampling scopes]] | [[Category:Sampling scopes]] | ||
[[Category:661 series scopes]] | [[Category:661 series scopes]] | ||