502
The Tektronix 502 is a dual-beam oscilloscope introduced in 1958, followed by the 502A in 1963. There is also a rack-mount model, the RM502A.
Both beams have differential inputs. The horizontal deflection plates are common to both beams.
Mod 104 on a 502 provides single sweep lockout. This feature is standard on the 502A, which also has beam finder switches for each channel.
A recessed switch in the left side panel allows the upper beam amplifier to be connected to the horizontal deflection plates for single-beam X-Y operation, providing a differential X input with the same sensitivity as the Y channel. The upper beam is positioned off screen in this mode.
If the combination of time base setting and magnification selector results in a sweep faster than 1 μs/div, the horizontal scale is not calibrated, and a lamp on the front panel lights up to remind the operator of that.
Key Specifications
Deflection | 100 μV/cm to 20 V/cm, 1−2−5, ±3% |
---|---|
Bandwidth | 1 MHz @ 200 mV/cm and above; 400 kHz @ 50 mV/cm, 200 kHz @ 5 mV/cm, 100 kHz @ 200 μV/cm |
CMRR | 502A: 40,000:1 @ 100 mV/cm and 1 kHz |
Input impedance | 1 MΩ // 47 pF |
Sweep | 1 μs/cm to 5 s/cm, 1−2−5, ±3%; magnifier ×2, ×5, ×10 or ×20 |
CRT | Early 502: Type T60P2/T502P2/T5020P2; Late 502, 502A: Type T5021P2; (P1, P7 or P11 were available as options) 10 vertical and 10 horizontal 1 cm divisions 3 kV acceleration |
Dimensions | 597 mm (23½") × 286 mm (11¼") × 381 mm (15") L×W×H |
Weight | 23.6 kg (52lb) |
Prices
Year | 1959 | 1961 | 1963 (A) | 1971 (A) |
---|---|---|---|---|
Catalog price | $825 | $825 | $1,050 | $1,265 |
2021 value | $7,740 | $7,530 | $9,370 | $8,530 |
Internals
The −150 V supply uses a 5651 voltage reference tube as its reference.
The 6.2 VDC heater supply for the tubes in the first stage differential amplifier is transistor-regulated. This heater supply uses the −150 V supply as its reference.
There is no post-deflection acceleration. The CRT cathode voltage is −2.9 kV.
The early 502 uses a single supply for the upper beam and lower beam CRT cathodes (HV transformer 120-114). Later models (1959+, see 070-090) and the 502A have separate supplies for the two CRT cathodes (HV transformer 120-150). This improvement allows slight differences in horizontal CRT sensitivity between the two beams to be cancelled out in step 8 of the calibration procedure.
Later 502A models have a solid state (plus nuvistor) input stage, a 6DJ8 as the deflection amplifier, and transistors as amplifiers and emitter followers (only in the newest version).
The 502 has a 123 °F (50.5 °C) thermal cutoff switch.
Links
- Tektronix 502A @ amplifier.cd (many internal pictures)
- Tektronix 502A internals @ youtube (German)
Pictures
502
502A
RM502A
Third version 502A, serial number ≥31,000
Diagrams
Early 502 CRT circuit, 120-114 transformer (secondary transformer pin numbers incorrect)
Later 502 CRT circuit, 120-150 transformer
502A CRT circuit, 120-150 transformer
Cartoon in schematic: Mountain Climber
Applications
Some Parts Used in the 502
Page | Class | Description | Used in |
---|---|---|---|
120-117 | Discrete component | power transformer | 502 |
12AT7 | Vacuum Tube (Dual Triode) | dual high-gain triode | 161 • 180 • 310 • 310A • 315 • 316 • 360 • 502 • 502A • 511A • 512 • 513 • 513D • 514 • 514AD • 514D • 516 • 524 • 529 • RM529 • 544 • 546 • 547 • 556 • 3A2 • 3A75 • 1M1 • A • B • C • G • H • K • L • M • N • K • R • S • Z |
12AU7 | Vacuum Tube (Dual Triode) | dual medium-μ triode | 104 • 104A • 122 • 160 • 161 • 162 • 181 • 190 • 310 • 316 • 317 • 502 • 502A • 511A • 512 • 516 • 517 • 517A • 524 • 526 • 535 • 536 • 545 • 545A • 545B • 547 • 549 • 555 • 575 • 581 • 581A • 585 • 585A • C • D • E • N • Q |
12B4 | Vacuum Tube (Triode) | power triode | 126 • 310 • 310A • 316 • 317 • 502 • 502A • 524 • 526 • 541 • 541A • 535 • 535A • 545 • 545A • 546 • 547 • 549 • 551 • 555 • 513 • 581 • 581A • 585 • 585A |
5642 | 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 • 567 • 575 • 581 • 581A • 585 • 585A • 647 |
5651 | Gas Discharge Tube (Voltage regulator) | 87 V (at 3.5 mA) voltage reference | 128 • 160 • 310 • 310A • 502 • 503 • 504 • 511A • 512 • 516 • 517 • 524 • 526 • 536 • 581 • 585 • 549 • 535 |
5AR4 | Vacuum Tube (Dual Rectifier) | dual rectifier | 502 • 502A |
6AL5 | Vacuum Tube (Dual Diode) | high-perveance dual diode | 163 • 181 • 190 • 1M1 • 310 • 310A • 315 • 316 • 317 • 502 • 502A • 503 • 511 • 511A • 512 • 516 • 517 • 517A • 524 • 526 • 535 • 535A • 545 • 545A • 549 • 581 • 581A • 585 • 585A • 551 • C • T • Telequipment S52 |
6AN8 | Vacuum Tube (Triode/Pentode) | triode-pentode combo | 310 • 310A • 316 • 317 • 360 • 502 • 502A • 516 • 517 • 517A • 526 • 575 • N |
6AU6 | Vacuum Tube (Pentode) | RF pentode | 2A60 • 80 • 107 • 160 • 181 • 190 • 310 • 310A • 316 • 317 • 360 • 502 • 502A • 511A • 512 • 513 • 516 • 517 • 517A • 524 • 526 • 529 • RM529 • 531 • 531A • 535 • 536 • 545 • 545A • 546 • 547 • 549 • 555 • 575 • 581 • 581A • 585 • 585A • C • CA • Q |
6BW4 | Vacuum Tube (Dual Diode) | dual diode | 126 • 502 • 502A • 524 • 575 |
6CZ5 | Vacuum Tube (Pentode) | power pentode | 317 • 502 • 526 • 555 • 561 • 561A • 561S • 564 • 567 |
6DJ8 | Vacuum Tube (Dual Triode) | 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 |
8056 | Vacuum Tube (Triode) | low-voltage Nuvistor triode | 422 • 502 • W • 1S1 • 3A7 • 3S3 • 3T4 • 5T3 • 10A1 |
T502 | CRT | dual-beam CRT | 502 |
Some Parts Used in the 502A
Page | Class | Description | Used in |
---|---|---|---|
12AT7 | Vacuum Tube (Dual Triode) | dual high-gain triode | 161 • 180 • 310 • 310A • 315 • 316 • 360 • 502 • 502A • 511A • 512 • 513 • 513D • 514 • 514AD • 514D • 516 • 524 • 529 • RM529 • 544 • 546 • 547 • 556 • 3A2 • 3A75 • 1M1 • A • B • C • G • H • K • L • M • N • K • R • S • Z |
12AU7 | Vacuum Tube (Dual Triode) | dual medium-μ triode | 104 • 104A • 122 • 160 • 161 • 162 • 181 • 190 • 310 • 316 • 317 • 502 • 502A • 511A • 512 • 516 • 517 • 517A • 524 • 526 • 535 • 536 • 545 • 545A • 545B • 547 • 549 • 555 • 575 • 581 • 581A • 585 • 585A • C • D • E • N • Q |
12B4 | Vacuum Tube (Triode) | power triode | 126 • 310 • 310A • 316 • 317 • 502 • 502A • 524 • 526 • 541 • 541A • 535 • 535A • 545 • 545A • 546 • 547 • 549 • 551 • 555 • 513 • 581 • 581A • 585 • 585A |
5642 | 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 • 567 • 575 • 581 • 581A • 585 • 585A • 647 |
5AR4 | Vacuum Tube (Dual Rectifier) | dual rectifier | 502 • 502A |
6AL5 | Vacuum Tube (Dual Diode) | high-perveance dual diode | 163 • 181 • 190 • 1M1 • 310 • 310A • 315 • 316 • 317 • 502 • 502A • 503 • 511 • 511A • 512 • 516 • 517 • 517A • 524 • 526 • 535 • 535A • 545 • 545A • 549 • 581 • 581A • 585 • 585A • 551 • C • T • Telequipment S52 |
6AN8 | Vacuum Tube (Triode/Pentode) | triode-pentode combo | 310 • 310A • 316 • 317 • 360 • 502 • 502A • 516 • 517 • 517A • 526 • 575 • N |
6AU6 | Vacuum Tube (Pentode) | RF pentode | 2A60 • 80 • 107 • 160 • 181 • 190 • 310 • 310A • 316 • 317 • 360 • 502 • 502A • 511A • 512 • 513 • 516 • 517 • 517A • 524 • 526 • 529 • RM529 • 531 • 531A • 535 • 536 • 545 • 545A • 546 • 547 • 549 • 555 • 575 • 581 • 581A • 585 • 585A • C • CA • Q |
6BW4 | Vacuum Tube (Dual Diode) | dual diode | 126 • 502 • 502A • 524 • 575 |
6DJ8 | Vacuum Tube (Dual Triode) | 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 |
6DT5 | Vacuum Tube (Pentode) | power pentode | 502A |
T5021 | CRT | dual-beam CRT | 502A |