The Tektronix 561 is a 560-series scope that was introduced in 1961 and produced in various versions well into the 1970s. The designer of the 561 was Bob Shand.

Versions

Over its life, the 561 was actually a series of four very different scopes, plus the rack mount versions of each.

561

The original 561 and RM561 were introduced in 1961. Similar to the 560, also introduced in 1961, the 561 has a round CRT. It supports the 50, 60 and 70 series of plug-ins, with the highest system bandwidth of 4 MHz. The later 2- and 3- series plug-ins cannot be used in the 560 or 561, as they consume more power. Early, low power, plugins have the nylon guide on their backplane pointing into the plugin, while the later, higher power consuming, plugins have those nylon guides pointing outward. The outward pointing guide will bump into the chassis of a 560 or 561, preventing it from fully inserting. The 561A and all later 560 series scopes, with higher capability power supplies, have a hole in the chassis that allows the outward pointing nylon guide to clear, allowing full insertion.

The 561 uses the T5032 CRT, which has a glass envelope. The 561 and later versions also had a front panel calibrator signal for calibrating the plugins to the mainframe. The 561 calibrator has 18 attenuation steps and can output a square wave with an amplitude of 200 μV to 100 V.

Early serial numbers of the 561 use a neon bulb (B633) in the -100 V regulator circuit, however, later versions (including the 561A and later) used a transistor. The modification for early units is documented at the end of the 561 manual and in the 040-288 Field Modification Instructions.

Documents Referencing 561

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561A

The short lived 561 was replaced by the 561A and the rack-mount version RM561A in 1962. The 561A were the highest selling model in the 560 series.

They introduced a revolutionary new CRT, the T5610, incorporating many “firsts” that would remain through most of Tek's analog scopes to follow – a rectangular faceplate allowing for a more compact CRT, and a ceramic CRT envelope which provided more mechanical precision than a blown glass tube. This also enabled the use of a separate face plate made from a flat glass panel that could have the graticule markings printed on the phosphor side of the faceplate, totally eliminating parallax errors, and allowing for better edge illumination.

The 561A was one of the mainframes offered for the Engine Analyzer System.

An RM561A with two custom plug-ins was incorporated (upside-down) as the standard display in the LINC computer.

The Mod210C replaced the T5610 ceramic CRT with the T5032 glass CRT and an external graticule. The graticule illumination was changed to red and the BNC connectors of the scope and plugins were replaced with UHF connectors. The graticule has an engraved sinewave. A green light filter was added between the CRT and the graticule.

Documents Referencing 561A

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561B

The 561B / RM561B were introduced in 1969. The 561B uses the same 560-series plug-ins used by the 561A. The 561B models actually provided no performance improvements over the 561A, with the change being limited to all solid state design, including the HV rectifiers. While this change improves reliability of the mainframe, Tektronix never produced fully solid state amplifier or non-sampling timebase plug-ins for the 560 Series.

Documents Referencing 561B

Document Class Title Authors Year Links
070-0890-00.pdf Manual Engine Analyzer System 1968
Tekscope 1969 V1 N1 Feb 1969.pdf Article An Extended Value John Durecka 1969
Tekscope 1969 V1 N2 Apr 1969.pdf Article A New Insight Into Reciprocating Machinery Bill Verhoef 1969

Patents that may apply to 561B

Page Title Inventors Filing date Grant date Links
Patent US 3453403A Power selection device Eldon Hoffman 1966-08-18 1969-07-01

561S

A special 561S was introduced as a special product, modified from a 561A. It did not appear in any Tek catalog. With special modified amplifier and time base (3A1S and 3B1S), and a special CRT (T5033), it achieved a 25 MHz system bandwidth, which is 2.5 times the bandwidth of a 561A.

The 3A1S and 3B1S were the only plug-ins that could be used in the 561S because the T5033 CRT has higher deflection sensitivity than the CRT used in the 561, 561A, and 561B. The vertical deflection sensitivity of the T5033 is 11.7 V/cm. The 561A has the T561 CRT which has a vertical deflection sensitivity of 19.5 V/cm.

The higher bandwidth of the 561S came at the expense of trading off some of the advances gained in the original 561A. The CRT is a conventional glass envelope, without internal graticule. Also, the scale was reduced from 8 × 10 divisions to 6 × 10. The 561S has no post-deflection acceleration, and a CRT cathode voltage of -3,300 V, like the other 561 models.

Documents Referencing 561S

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Plugin Compatibility

The popular 60 and 70 series plug-ins were later given a “2A, 2B, 3A, or 3B” prefix. The highest bandwidth plug-ins gave a system bandwidth of 10 MHz when used in the 561A and 561B.

The 561A, RM561A, 561B, and RM561B are compatible with all of the 2 and 3-series plugins that Tektronix made. The 561 and RM561 have limited compatibility with some 3-series plugins, mainly due to the CRT circuit. For plugins such as the 3B1 and 3B3 time bases there are issues with the blanking and intensified sweep. The 561A and subsequent models used a dual-secondary winding transformer in the CRT power supply, with one winding used in an intensifying pulse circuit which the original 561 lacked. Other 3-series plugins may be used in the original 561 with some modifications – for example, to use a 3A74 4-channel vertical plugin in a 561 sn101 to 579, the +6 V unregulated supply needs to be disconnected from both plugin connectors (pin 18). Later 561's with sn580 and higher already had this change implemented. More information regarding the use of 3-series plugins and the required modifications (if available) can be found in the Tektronix 561 Instrument Reference Book (IRB).

Key Specifications

     — 561
Bandwidth DC to 4 MHz (with 3A75, may vary with other plug-ins)
Rise time 0.09 μs
Power Consumption 185 W with 72 & 67 plug-ins
     — 561A & 561B
Bandwidth DC to 15 MHz (with 3A5, may vary with other plug-ins)
Rise time 0.024 μs
Power Consumption 178 W with plug-ins
     — 561S
Bandwidth DC to 25 MHz (with 3A1S, may vary with other plug-ins)
Rise time 0.014 μs
Power Consumption 210 W to 240 W with plug-ins
     — all
Line Voltage 105-125/210-250 VAC ±10%, selected via primary voltage selector and voltage range selector switches, 50 Hz to 60 Hz.
Thermal Protection Automatic resetting thermal cutout, in case internal temperature exceeds safe operating level
Anode Potential 3.5 kV
Screen Area 8 cm × 10 cm ( 561S: 6 cm x 10 cm )
Construction Aluminum alloy chassis. Anodized front panel

Links

Pictures

561

RM561

561A

561A/MOD210C

RM561A

561B

R561B

561S

Components

Some Parts Used in the 561

Part Part Number(s) Class Description Used in
0G3 154-0291-00 Gas Discharge Tube (Voltage regulator) 85 V voltage reference 132 506 547 560 561 561A 561S 564 565 567 661 TU-4 Z Keithley 610
12AU7 154-041 154-0041-00 154-0287-00 Vacuum Tube (Dual Triode) dual medium-μ triode 104 104A 122 160 161 162 181 190 310 310A 316 317 3C66 502 502A 507 511A 512 516 517 517A 524 526 535 536 545 545A 545B 547 549 555 561 564 570 575 581 581A 585 585A C D E N Q Hickok 1825
5642 154-0051-00 154-0079-00 Vacuum Tube (Diode) directly-heated high-voltage rectifier 310 310A 316 317 360 453 502 502A 503 504 506 513 515 516 524 529 RM529 533 533A 535 536 543 543A 543B 545 545A 545B 547 551 555 556 560 561 561A 561S 564 567 570 575 581 581A 585 585A 647 647A
6AS7 154-020 154-0020-00 Vacuum Tube (Pentode) dual power triode 160 506 511A 512 513 517 517A 524 561 561A 561S 564
6AU6 154-0022-00 157-0073-00 157-0059-00 154-0284-00 Vacuum Tube (Pentode) RF pentode 107 160 181 190 60 2A60 72 3A72 3C66 310 310A 316 317 360 502 502A 506 511 511A 512 513 516 517 517A 524 526 529 RM529 531 531A 535 536 545 545A 546 547 549 555 561 561A 561S 564 565 567 570 575 581 581A 585 585A 80 C CA Q
6BL8 154-0278-00 Vacuum Tube (Triode/Pentode) triode-pentode combo 67 2B67 3B1 3B1S 3B2 3B3 3B4 503 504 506 516 549 561 561A 561S 564 565 567 Telequipment D52 Telequipment D56 Telequipment S31 Telequipment S32 Telequipment S32A Telequipment S51 Telequipment S52
6CZ5 154-0167-00 Vacuum Tube (Pentode) power pentode 317 502 506 526 555 561 561A 561S 564 565 567
7233 154-307 154-0307-00 Vacuum Tube (Triode) low-mu triode 132 506 561 561A 561S 564 565
T5030 154-0264-00 154-0265-00 154-0266-00 154-0267-00 154-0341-00 CRT CRT 503 504 560 561 661
T5032 154-0319-00 154-0320-00 154-0321-00 154-0322-00 154-0355-00 154-0372-00 154-0373-00 154-0374-00 154-0375-00 154-0376-00 154-0377-00 154-0449-00 154-0454-00 154-0455-00 154-0456-00 CRT 5" rectangular-faceplate CRT 561 567


Some Parts Used in the 561A

Part Part Number(s) Class Description Used in
0G3 154-0291-00 Gas Discharge Tube (Voltage regulator) 85 V voltage reference 132 506 547 560 561 561A 561S 564 565 567 661 TU-4 Z Keithley 610
12BH7 154-0046-00 Vacuum Tube (Dual Triode) dual triode 506 517A 561A 561S 564 567
5642 154-0051-00 154-0079-00 Vacuum Tube (Diode) directly-heated high-voltage rectifier 310 310A 316 317 360 453 502 502A 503 504 506 513 515 516 524 529 RM529 533 533A 535 536 543 543A 543B 545 545A 545B 547 551 555 556 560 561 561A 561S 564 567 570 575 581 581A 585 585A 647 647A
6AS7 154-020 154-0020-00 Vacuum Tube (Pentode) dual power triode 160 506 511A 512 513 517 517A 524 561 561A 561S 564
6AU6 154-0022-00 157-0073-00 157-0059-00 154-0284-00 Vacuum Tube (Pentode) RF pentode 107 160 181 190 60 2A60 72 3A72 3C66 310 310A 316 317 360 502 502A 506 511 511A 512 513 516 517 517A 524 526 529 RM529 531 531A 535 536 545 545A 546 547 549 555 561 561A 561S 564 565 567 570 575 581 581A 585 585A 80 C CA Q
6BL8 154-0278-00 Vacuum Tube (Triode/Pentode) triode-pentode combo 67 2B67 3B1 3B1S 3B2 3B3 3B4 503 504 506 516 549 561 561A 561S 564 565 567 Telequipment D52 Telequipment D56 Telequipment S31 Telequipment S32 Telequipment S32A Telequipment S51 Telequipment S52
6CZ5 154-0167-00 Vacuum Tube (Pentode) power pentode 317 502 506 526 555 561 561A 561S 564 565 567
6DJ8 154-0187-00 154-0305-00 Vacuum Tube (Dual Triode) dual triode 111 132 161 310A 316 317 502 502A 503 504 506 515 516 519 526 529 RM529 533 535 536 543 544 545 545A 545B 546 547 549 555 556 561A 561S 564 565 567 581 581A 585 585A 661 1A4 1S1 60 2A60 63 2A63 67 2B67 3A1 3A1S 3A2 3A3 3A6 3A7 72 3A72 75 3A75 4S2 51 3B1 3B1S 3B2 3B3 3B4 3M1 3S76 3T77 3T77A 9A1 9A2 1121 80 81 82 86 B O W Z Telequipment D56 Telequipment S32A Telequipment D52 S-311 Telequipment TD51 Telequipment S52 Telequipment S51 Telequipment Type A TU-4
7233 154-307 154-0307-00 Vacuum Tube (Triode) low-mu triode 132 506 561 561A 561S 564 565
T5610 154-0396-00 154-0397-00 154-0398-00 154-0399-00 154-0400-00 154-0401-00 154-0402-00 154-0403-00 154-0404-00 154-0405-00 154-0406-00 154-0407-00 CRT rectangular-faceplate CRT 561A
T5611 154-0531-00 154-0531-01 154-0531-02 154-0531-03 154-0613-00 154-0613-01 154-0613-02 154-0613-03 154-0614-00 154-0614-01 154-0614-02 154-0614-03 CRT ceramic CRT 561A 561B 567 568


Some Parts Used in the 561B

Part Part Number(s) Class Description Used in
120-0575-00 120-0575-00 Discrete component power transformer 561B
2N3739 151-0201-00 Discrete component Silicon NPN power transistor 013-002 106 4501 561B R561B 564B R564B 568 7503 7504
T5611 154-0531-00 154-0531-01 154-0531-02 154-0531-03 154-0613-00 154-0613-01 154-0613-02 154-0613-03 154-0614-00 154-0614-01 154-0614-02 154-0614-03 CRT ceramic CRT 561A 561B 567 568


Some Parts Used in the 561S

Part Part Number(s) Class Description Used in
0G3 154-0291-00 Gas Discharge Tube (Voltage regulator) 85 V voltage reference 132 506 547 560 561 561A 561S 564 565 567 661 TU-4 Z Keithley 610
12BH7 154-0046-00 Vacuum Tube (Dual Triode) dual triode 506 517A 561A 561S 564 567
5642 154-0051-00 154-0079-00 Vacuum Tube (Diode) directly-heated high-voltage rectifier 310 310A 316 317 360 453 502 502A 503 504 506 513 515 516 524 529 RM529 533 533A 535 536 543 543A 543B 545 545A 545B 547 551 555 556 560 561 561A 561S 564 567 570 575 581 581A 585 585A 647 647A
6AS7 154-020 154-0020-00 Vacuum Tube (Pentode) dual power triode 160 506 511A 512 513 517 517A 524 561 561A 561S 564
6AU6 154-0022-00 157-0073-00 157-0059-00 154-0284-00 Vacuum Tube (Pentode) RF pentode 107 160 181 190 60 2A60 72 3A72 3C66 310 310A 316 317 360 502 502A 506 511 511A 512 513 516 517 517A 524 526 529 RM529 531 531A 535 536 545 545A 546 547 549 555 561 561A 561S 564 565 567 570 575 581 581A 585 585A 80 C CA Q
6BL8 154-0278-00 Vacuum Tube (Triode/Pentode) triode-pentode combo 67 2B67 3B1 3B1S 3B2 3B3 3B4 503 504 506 516 549 561 561A 561S 564 565 567 Telequipment D52 Telequipment D56 Telequipment S31 Telequipment S32 Telequipment S32A Telequipment S51 Telequipment S52
6CZ5 154-0167-00 Vacuum Tube (Pentode) power pentode 317 502 506 526 555 561 561A 561S 564 565 567
6DJ8 154-0187-00 154-0305-00 Vacuum Tube (Dual Triode) dual triode 111 132 161 310A 316 317 502 502A 503 504 506 515 516 519 526 529 RM529 533 535 536 543 544 545 545A 545B 546 547 549 555 556 561A 561S 564 565 567 581 581A 585 585A 661 1A4 1S1 60 2A60 63 2A63 67 2B67 3A1 3A1S 3A2 3A3 3A6 3A7 72 3A72 75 3A75 4S2 51 3B1 3B1S 3B2 3B3 3B4 3M1 3S76 3T77 3T77A 9A1 9A2 1121 80 81 82 86 B O W Z Telequipment D56 Telequipment S32A Telequipment D52 S-311 Telequipment TD51 Telequipment S52 Telequipment S51 Telequipment Type A TU-4
7233 154-307 154-0307-00 Vacuum Tube (Triode) low-mu triode 132 506 561 561A 561S 564 565
T5033 154-0748-00 CRT 5" CRT 561S 506