Vacuum tubes
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Vacuum tubes aka electron tubes or (thermionic) valves were the workhorse active components in electronics up to the mid-1960s.
Tube selection
The mechanical tolerances in vacuum tube manufacturing lead to a slight variation in many tube parameters, e.g. the I/V curves, and the dynamic behavior. Further, tubes exhibit a slight change in performance in the first hours of operation.
While those variations are acceptable in many applications, Tektronix chose to age most of their used tubes to avoid the alteration of performance in the first hours of operation of new equipment, or when replacing tubes. In many applications, the same tube was further selected after aging for parameters as low grid current or matched in pairs for a particular bias condition. (In contrast to popular belief in the audiophile world, a "matched pair" of tubes is meaningless, unless the exact bias condition in operation is known and tubes are matched in that condition.)
This is the reason why there are often five or six different part numbers for the same tube, since they were differently selected.Tektronix used 157- as the part number prefix for aged/checked/matched tubes (e.g,157-0006-00 ), whereas raw tubes including CRTs were identified with 154- prefix (e.g.,154-0031-00).
Tube failure
Important failure modes of vacuum tubes include:
Loss of vacuum
aka tube "getting gassy" − can be caused by glass leak, electrode/glass interface leak, broken glass.
Can often be detected by visual inspection in glass-envelope tubes, either when the envelope is visibly cracked, or if the getter (silver-colored metallic patch) has turned white or entirely disappeared.
Gassy tubes will draw more than the nominal heater power because convection transports heat away from the filament.
Slightly gassy tubes may exhibit a blue glow from inside (ionization of gas molecules by the electron beam) when operated with plate/grid supplies present.
Tubes with pristine getter
Gassy tube, getter turned white and partly fallen off
Gassy tubes, getter turned white
Gassy tubes, getter almost completely gone
Filament failure
broken/burned out filament (open circuit)
Loss of cathode emission
Can be measured on a tube tester or using a test jig.
Grid emission
Transport of cathode emission material to the grid can allow the grid to emit electrons when warm. This will alter the grid voltage if the grid circuit DC resistance is large. This problem is more common in certain tube types and is sometimes caused by operating the cathode/heater at higher power and higher temperature. Some Tek inputs that connect directly to vacuum tube grids also incorporate temperature sensitive circuits to null out the grid current.
Electrode damage
- electrode damage (e.g. melting) caused by overloads − grid wires are most sensitive
- bent electrodes or internal structures (especially noticeable in CRTs) − may be caused by excessive G force application such as dropping
Either of these can also lead to inter-electrode shorts.
Links
- Vacuum tube @ Wikipedia
- Tube Basing Index (PDF, needs OCR)
Tubes used in Tektronix Instruments
- → See separate page for Cathode-ray tubes (CRTs).
| Page | Class | Model | Part nos | Description | Used in |
|---|---|---|---|---|---|
| 12A4 | Vacuum Tube (Pentode) | 12A4 | 154-0037-00 | miniature 6.5 W power pentode | 517 • 517A |
| 12AL5 | Vacuum Tube (Double Diode) | 12AL5 aka HAA91 | 154-0038-00 | high-perveance dual diode | 545 • 545A • 549 • N |
| 12AT7 | Vacuum Tube (Dual Triode) | 12AT7 aka ECC81 | 154-0039-00 | dual high-gain triode | 161 • 180 • 310 • 310A • 315 • 316 • 360 • 502 • 502A • 512 • 513 • 513D • 514 • 514AD • 514D • 516 • 524AD • 529 • RM529 • 544 • 546 • 547 • 556 • 3A2 • 3A75 • 1M1 • A • B • C • G • H • K • L • M • N • K • R • S • Z |
| 12AU6 | Vacuum Tube (Pentode) | 12AU6 aka HF94 | 154-0040-00 | RF pentode | 81 • 112 • 512 • 556 • 575 • 545 • 549 • 581 • 585 • A • B • C • G • K • H • L • M • N • O • R • S • Z |
| 12AU7 | Vacuum Tube (Dual Triode) | 12AU7 aka ECC82 | 154-0041-00 • 154-0287-00 | dual medium-μ triode | 122 • 160 • 161 • 162 • 181 • 190 • 310 • 316 • 317 • 502 • 502A • 512 • 516 • 517 • 517A • 526 • 535 • 536 • 545 • 545A • 545B • 547 • 549 • 555 • 575 • 581 • 581A • 585 • 585A • C • D • E • N • Q |
| 12AW6 | Vacuum Tube (Pentode) | 12AW6 | 154-0042-00 | sharp cutoff pentode | 513 |
| 12AX7 | Vacuum Tube (Dual Triode) | 12AX7 aka ECC83 | 154-0043-00 | dual triode | 513 • 531 • 531A • 535 • 536 • 545 • 545A • 545B • 546 • 547 • 549 • 555 • 581 • 581A • 585 • 585A • E • Q |
| 12B4 | Vacuum Tube (Triode) | 12B4(A) | 154-0044-00 | power triode | 126 • 310 • 310A • 316 • 317 • 502 • 502A • 526 • 541 • 541A • 535 • 535A • 545 • 545A • 546 • 547 • 549 • 551 • 555 • 513 • 581 • 581A • 585 • 585A |
| 12BH7 | Vacuum Tube (Dual Triode) | 12BH7 | 154-0046-00 | dual triode | 517A |
| 12BW4 | Vacuum Tube (Dual Diode) | 12BW4 | dual diode | ||
| 12BY7 | Vacuum Tube (Pentode) | 12BY7 | miniature 6.5 W power pentode | 106 • 163 • 531 • 533 • 535 • 536 • 541 • 543 • 535 • 545 • 545A • 549 • 555 • 3A75 | |
| 12BY7A | Vacuum Tube (Pentode) | 12BY7A aka EL180 | 154-0047-00 | miniature 6.5 W power pentode | |
| 1X2 | Vacuum Tube (Diode) | 1X2 aka DY80 | 154-0005-00 | high-voltage rectifier | 507 • 565 • 420 |
| 4CX250F | Vacuum Tube (Pentode) | 4CX250F (7204) | 154-0300-00 | beam power tube | 519 |
| 5642 | Vacuum Tube (Diode) | 5642 aka DY70 (similar) | 154-0051-00 • 154-0079-00 | directly-heated high-voltage rectifier | 310 • 310A • 316 • 317 • 360 • 453 • 502 • 502A • 503 • 504 • 506 • 513 • 515 • 516 • 529 • RM529 • 533 • 533A • 535 • 536 • 543 • 543A • 543B • 545 • 545A • 545B • 547 • 551 • 555 • 556 • 567 • 575 • 581 • 581A • 585 • 585A • 647 |
| 5654 | Vacuum Tube (Pentode) | 5654 aka E95F | 154-0206-00 • 154-0084-00 | RF pentode | B • L |
| 5687 | Vacuum Tube (Dual Triode) | 5687 | dual triode | ||
| 5718 | Vacuum Tube (Triode) | 5718 aka EC71 | 154-0053-00 | subminiature high-frequency triode | 321 • P500CF • P170CF |
| 5751 | Vacuum Tube (Dual Triode) | 5751 | 154-0094-00 | dual triode | E |
| 5814 | Vacuum Tube (Double Triode) | 5814 | 154-0054-00 • 154-0316-00 | twin medium-μ triode | D |
| 5842 | Vacuum Tube (Triode) | 5842 aka CK5842 aka 417A | 157-0098-00 | high-gm UHF triode | 2A61 |
| 5879 | Vacuum Tube (Pentode) | 5879 | 154-0055-00 | sharp-cutoff pentode | 112 • 512 • D • E |
| 5894 | Vacuum Tube (Tetrode) | 5894 aka QQE06/40 | 154-0130-00 | dual power tetrode | 536 |
| 5AR4 | Vacuum Tube (Dual Rectifier) | 5AR4 aka GZ34 | 154-0168-00 | dual rectifier | 502 • 502A |
| 5R4GY | Vacuum Tube (Dual Rectifier) | 5R4GY | 154-0007-00 | dual rectifier | 517 • 517A |
| 5V4 | Vacuum Tube (Dual Rectifier) | 5V4 | dual rectifier | 160 | |
| 5V4G | Vacuum Tube (Dual Rectifier) | 5V4G | dual rectifier | 160 • 514 | |
| 5Y3 | Vacuum Tube (Diode) | 5Y3 | rectifier | 190 | |
| 5Y3GT | Vacuum Tube (Dual Rectifier) | 5Y3GT | 154-0009-00 | dual rectifier | |
| 6080 | Vacuum Tube (Dual Triode) | 6080 aka ECC230 | 154-0056-00 • 154-0315-00 | dual power triode | 132 • 160 • 316 • 317 • 535 • 535A • RM35A • 541 • 541A • 535 • 536 • 545 • 545A • 545B • 546 • 547 • 549 • 575 • 581 • 581A • 585 • 585A |
| 6110 | Vacuum Tube (Dual Diode) | 6110 | 154-0240-00 | small-signal dual diode | 190 |
| 6197 | Vacuum Tube (Pentode) | 6197 | 154-0146-00 | sharp-cutoff pentode | 516 • 531 • 533 • 535 • 535A • 556 • 3A75 |
| 6201 | Vacuum Tube (Dual Triode) | 6201 aka E81CC | dual high-gain triode | Nelson-Ross PSA-011 | |
| 6360 | Vacuum Tube (Pentode) | 6360 aka QQE03/12 | 154-0191-00 | dual beam power tube | 536 |
| 6688 | Vacuum Tube (Pentode) | 6688 aka E180F | miniature high-slope VHF/UHF pentode | P80 • 3T77 • 526 • TR-4602 | |
| 6939 | Vacuum Tube (Dual Tetrode) | 6939 aka QQE02/5, QQV02/6 | dual tetrode | 581 • 585 | |
| 6AG7 | Vacuum Tube (Pentode) | 6AG7 | 154-0012-00 | 9 Watt power pentode | 104 • 105 • 112 • 511 • 512 • 513 • 514 • 517 • 517A • 524 |
| 6AK5 | Vacuum Tube (Pentode) | 6AK5 aka EF95 aka 6Ж1П | 154-0014-00 • 154-0206-00 • 154-0084-00 | RF pentode | B • C • CA • G • K • L • S • Z • 517 • 517A |
| 6AK6 | Vacuum Tube (Pentode) | 6AK6 | 154-0015-00 | power pentode | 315 |
| 6AL5 | Vacuum Tube (Dual Diode) | 6AL5/12AL5 aka EAA91/EB91/HAA91 | 154-0016-00 • 154-0038-00 | high-perveance dual diode | 163 • 181 • 190 • 310 • 310A • 315 • 316 • 317 • 502 • 502A • 503 • 511 • 511A • 512 • 516 • 517 • 517A • 526 • 535 • 535A • 545 • 545A • 549 • 581 • 581A • 585 • 585A • 551 • C • T • Telequipment S52 |
| 6AN8 | Vacuum Tube (Triode/Pentode) | 6AN8 | 154-0078-00 | triode-pentode combo | 310 • 310A • 316 • 317 • 360 • 502 • 502A • 516 • 517 • 517A • 526 • 575 • N |
| 6AQ5 | Vacuum Tube (Pentode) | 6AQ5 aka EL90 | 154-0017-00 | beam pentode | 310 • 310A • 316 • 360 • 512 • 517 • 517A • 536 • 575 |
| 6AR8 | Vacuum Tube (Pentode) | 6AR8 | 154-0200-00 | beam-switching tube | 526 |
| 6AS5 | Vacuum Tube (Pentode) | 6AS5 | 154-0018-00 | 5.5 W beam pentode | 517 • 517A |
| 6AS7 | Vacuum Tube (Pentode) | 6AS7/6AS7G | 154-0020-00 | dual power triode | 160 • 512 • 513 • 517 • 517A |
| 6AU5 | Vacuum Tube (Pentode) | 6AU5 | 10 W beam power pentode | 513 • 516 • 517 • 517A • 531 • 535 • 541 • 535 • 545 • 581 • 581A • 585 • 585A | |
| 6AU6 | Vacuum Tube (Pentode) | 6AU6 aka EF94 aka 6Ж4П | 154-0022-00 • 157-0073-00 • 157-0059-00 • 154-0284-00 | RF pentode | 2A60 • 80 • 107 • 160 • 181 • 190 • 310 • 310A • 316 • 317 • 360 • 502 • 502A • 512 • 513 • 516 • 517 • 517A • 526 • 529 • RM529 • 531 • 531A • 535 • 536 • 545 • 545A • 546 • 547 • 549 • 555 • 575 • 581 • 581A • 585 • 585A • C • CA • Q |
| 6AU8 | Vacuum Tube (Triode/Pentode) | 6AU8 | 154-0132-00 | triode-pentode combo | T |
| 6AW8 | Vacuum Tube (Triode/Pentode) | 6AW8 | 154-0095-00 | triode-pentode combo | 132 • 160 • 541 • 535 • 545 |
| 6BA8 | Vacuum Tube (Triode/Pentode) | 6BA8 | triode-pentode combo | 3A2 | |
| 6BA8A | Vacuum Tube (Triode/Pentode) | 6BA8A | 154-0163-00 | triode-pentode combo | 59 • 526 |
| 6BC7 | Vacuum Tube (Diode) | 6BC7 | 154-0232-00 | triple diode | 503 • 504 |
| 6BH6 | Vacuum Tube (Pentode) | 6BH6 | 154-0026-00 • 154-0285-00 | pentode | 162 • 310 • 310A • 512 • 517 • 517A • Nelson-Ross PSA-011 |
| 6BJ7 | Vacuum Tube (Diode) | 6BJ7 | 154-0453-00 | triple diode | 503 • 526 |
| 6BL8 | Vacuum Tube (Triode/Pentode) | 6BL8 aka ECF80 aka 6Ф1П | 154-0278-00 | triode-pentode combo | 503 • 504 • 516 • 549 • Telequipment D52 • Telequipment S31 • Telequipment S32 • Telequipment S32A • Telequipment S51 • Telequipment S52 |
| 6BQ5 | Vacuum Tube (Pentode) | 6BQ5 aka EL84 | power pentode | ||
| 6BQ7 | Vacuum Tube (Dual Triode) | 6BQ7 | dual triode | 315 | |
| 6BQ7A | Vacuum Tube (Dual Triode) | 6BQ7A aka ECC180/E180CC | 154-0028-00 • 157-0022-00 • 157-0003-00 | dual triode | 107 • 163 • 310 • 316 • 360 • 181 • 315 • 524 • 531 • 532 • 535 • 536 • 541 • 545 • T |
| 6BW4 | Vacuum Tube (Dual Diode) | 6BW4 | 154-0119-00 | dual diode | 126 • 502 • 502A • 575 |
| 6C4 | Vacuum Tube (Triode) | 6C4 aka EC90 | 154-0029-00 | VHF triode | 190 • 517 • 517A |
| 6CA4 | Vacuum Tube (Dual Rectifier) | 6CA4 aka EZ81 | 154-0119-00 | dual rectifier | Telequipment S31 • Telequipment S32 |
| 6CB6A | Vacuum Tube (Pentode) | 6CB6(A) aka EF190 | 154-0030-00 | pentode | 105 • 112 • 316 • 317 • 503 • 504 • 513 • 517 • 517A • 541 • 535 • 545 • 63 • 2A63 |
| 6CD6GA | Vacuum Tube (Pentode) | 6CD6-GA | 154-0112-00 | 20 W beam-power pentode | 570 |
| 6CG7 | Vacuum Tube (Dual Triode) | 6CG7 | 154-0134-00 | dual triode | 575 • Q |
| 6CL6 | Vacuum Tube (Pentode) | 6CL6 | 154-0031-00 • 154-0286-00 | miniature power pentode | 132 • 310 • 310A • 316 • 317 • 515 • 524 • 525 • 531 • 535 • 535A • 545 • 545A • 545B • 549 • 581 • 581A • 585 • 585A • 3A74 |
| 6CW4 | Vacuum Tube (Triode) | 6CW4 | 154-0323-00 | Nuvistor triode | 1A7 • 3A8 • 3B2 • 6R1 |
| 6CW5 | Vacuum Tube (Pentode) | 6CW5 aka EL86 | 154-0202-00 | power pentode | 132 • 526 • 547 |
| 6CY5 | Vacuum Tube (Tetrode) | 6CY5 | 154-0207-00 | tetrode | 581 • 585 • 581A • 585A |
| 6CZ5 | Vacuum Tube (Pentode) | 6CZ5 | 154-0167-00 | power pentode | 317 • 502 • 526 • 555 • 561 • 561A • 561S • 564 • 567 |
| 6DE7 | Vacuum Tube (Triode) | 6DE7 | 154-0188-00 | dual triode | 526 |
| 6DJ8 | Vacuum Tube (Dual Triode) | 6DJ8 aka ECC88 | 154-0187-00 • 154-0195-00 • 154-0305-00 • 154-0413-00 | dual triode | 80 • 132 • 161 • 310A • 316 • 317 • 3A75 • 502 • 502A • 503 • 504 • 515 • 516 • 519 • 526 • 529 • RM529 • 533 • 535 • 536 • 543 • 544 • 545 • 545A • 545B • 546 • 547 • 549 • 555 • 556 • 565 • 581 • 581A • 585 • 585A • 661 • 2A60 • 63 • 2A63 • 3A7 • 3A8 • 1121 • 1A4 • 67 • 81 • 82 • 86 • 3B1 • 3B4 • 1S1 • B • O • W • Z • Telequipment S32A • Telequipment D52 • Telequipment TD51 • Telequipment S52 • Telequipment S51 • Telequipment Type A |
| 6DK6 | Vacuum Tube (Pentode) | 6DK6 (8136) | 154-0149-00 • 154-0367-00 | high-frequency miniature pentode | 180 • 503 • 513 • 514 • 541 • 543 • 535 • 545 • 545A • 551 • 555 |
| 6DQ5 | Vacuum Tube (Pentode) | 6DQ5 | 154-0317-00 | beam power pentode | 560 |
| 6DQ6 | Vacuum Tube (Pentode) | 6DQ6 | 154-0277-00 | power pentode | 503 • 504 |
| 6DT5 | Vacuum Tube (Pentode) | 6DT5 | 154-0302-00 | power pentode | 502A |
| 6EJ7 | Vacuum Tube (Pentode) | 6EJ7 aka EF184 aka 6Ж51П | sharp-cutoff RF pentode | 526 • Telequipment S32A • Telequipment TD51 | |
| 6EW6 | Vacuum Tube (Pentode) | 6EW6 | 154-0212-00 | pentode | 132 • 360 • 527 • 581 • 581A • 585 • 585A |
| 6G11 | Vacuum Tube (Pentode) | 6G11 | 154-0660-00 | double sharp cut-off beam power pentode | 125 • 132 • 519 • 067-0502-01 • 050-0551-00 |
| 6GE8 | Vacuum Tube (Triode/Pentode) | 6GE8 | 154-0260-00 | triode-pentode combo | 125 • 132 |
| 6GF5 | Vacuum Tube (Pentode) | 6GF5 | 154-0494-00 | high voltage 9 Watt beam-power pentode | 549 • 556 |
| 6GM8 | Vacuum Tube (Dual Triode) | 6GM8 aka ECC86 aka 6Н27П | 154-0259-00 | dual triode | 81 • 516 • S |
| 6GV8 | Vacuum Tube (Triode/Pentode) | 6GV8 aka ECL85 | 154-0468-00 | triode-pentode combo | 526 • 529 • RM529 |
| 6HZ6 | Vacuum Tube (Pentode) | 6HZ6 | 154-0447-00 | pentode | 526 |
| 6J6 | Vacuum Tube (Dual Triode) | 6J6 aka ECC91 | 154-0032-00 | high-frequency dual triode | 161 • 512 • 517 • 517A |
| 6KV8 | Vacuum Tube (Triode/Pentode) | 6KV8 | triode-pentode combo | 3A8 | |
| 6L6 | Vacuum Tube (Pentode) | 6L6 | 154-0087-00 | beam power pentode | |
| 6M11 | Vacuum Tube (Pentode/Dual Triode) | 6M11 | 154-0493-00 | pentode and dual triode | 556 |
| 6U8 | Vacuum Tube (Triode/Pentode) | 6U8 aka ECF82 | 154-0033-00 | triode-pentode combo | 130 • 160 • 163 • 310 • 315 • 316 • 535 • 545 • T |
| 6V6 | Vacuum Tube (Pentode) | 6V6 | 154-0089-00 | 12-watt beam power pentode | |
| 6W4 | Vacuum Tube (Dual Rectifier) | 6W4/6W4GT | 154-0034-00 | dual rectifier | 512 |
| 6X4 | Vacuum Tube (Dual Rectifier) | 6X4 aka EZ90 | 154-0035-00 | dual rectifier | 128 • 130 • 181 • 512 • 517 • 517A |
| 6X8 | Vacuum Tube (Triode/Pentode) | 6X8 | 154-0036-00 | triode-pentode combo | |
| 7119 | Vacuum Tube (Dual Triode) | 7119 aka E182CC | dual triode | 067-0532-00 • 191 • 3A3 • 3B4 • 3B5 • 516 • 545B • 549 • 661 | |
| 7189 | Vacuum Tube (Pentode) | 7189 aka E84L | power pentode | ||
| 7189A | Vacuum Tube (Pentode) | 7189A | 154-0503-00 | power pentode | 106 |
| 7199 | Vacuum Tube (Triode/Pentode) | 7199 | 154-0309-00 | triode-pentode combo | |
| 7233 | Vacuum Tube (Triode) | 7233 | low-mu triode | 132 | |
| 7308 | Vacuum Tube (Dual Triode) | 7308 aka E188CC | 154-0371-00 | dual triode | 3S76 • 3S3 • 4S1 • 4S3 |
| 7586 | Vacuum Tube (Triode) | 7586 | 154-0306-00 | Nuvistor triode | M • 1A1 • 1A2 • 1A5 • 10A2 • 10A2A • 11B1 • 11B2A • 321 • 321A • 3A1 • 3A3 • 3A5 • 3A6 • 3A7 • 3A8 • 3A74 • 3S76 • 3S76A • 3T77 • 3T77A • 4S1 • 6R1 • 6R1A • 82 • 86 |
| 7587 | Vacuum Tube (Tetrode) | 7587 | 154-0465-00 | sharp-cutoff Nuvistor tetrode | 184 |
| 7693 | Vacuum Tube (Pentode) | 7693 aka E90F | 154-0026-00 • 154-0285-00 | pentode | |
| 7699 | Vacuum Tube (Dual Tetrode) | 7699 | dual tetrode | 581 • 585 | |
| 7734 | Vacuum Tube (Triode/Pentode) | 7734 | triode-pentode combo | 125 • 132 | |
| 7788 | Vacuum Tube (Pentode) | 7788 aka E810F aka 6Ж52П (similar) | 154-0420-00 | long life, shock and vibration resistant pentode | 529 • RM529 • 581A • 585A • RM581 • RM585 |
| 7895 | Vacuum Tube (Triode) | 7895 | 154-0378-00 | Nuvistor triode | 3B1 • 3B3 |
| 8056 | Vacuum Tube (Triode) | 8056 | 154-0417-00 | low-voltage Nuvistor triode | 422 • 502 • W • 1S1 • 3A7 • 3S3 • 3T4 • 5T3 • 10A1 |
| 8233 | Vacuum Tube (Pentode) | 8233 aka E55L | 154-0361-00 | special quality 10 watt pentode | 3A1 • 3A5 • 3A6 • 9A1 • 9A2 |
| 8393 | Vacuum Tube (Triode) | 8393 | 154-0461-00 | Nuvistor triode | 453 • 454 • 1A6 • 1A7 • 503 |
| 8425 | Vacuum Tube (Pentode) | 8425 | 154-0022-07 | RF pentode | 317 • 526 • Q |
| 8426 | Vacuum Tube (Pentode) | 8426 | RF pentode | O • 545A • 549 • 581A • 585A | |
| 8608 | Vacuum Tube (Pentode) | 8608 aka EL5070 | 154-0491-00 | 10-watt power pentode | 549 • 556 • 3A7 |
| CK512AX | Vacuum Tube (Pentode) | CK512AX | 154-0114-00 | flat-press subminiature pentode | 123 |
| EC1000 | Vacuum Tube (Triode) | 8254 aka EC1000 | subminiature triode | P6025 • P6032 |