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.
Key Specifications
Deflection | 100 μV/cm to 20 V/cm, 1−2−5, ±3% |
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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 | 502: Type T60P2/T502P2/T5020P2; 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) |
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Catalog price | $825 | $825 | $1,050 | $1,265 |
2018 value | $7,070 | $6,890 | $8,560 | $7,790 |
Internals
There is a transistor-regulated 6.2 VDC heater supply for the tubes in the first stage differential amplifier. This heater supply uses the −150 V supply as its reference. The −150 V supply uses a 5651 voltage reference tube as its reference. There is no post-deflection acceleration. The CRT cathode voltage is −2900 V.
Later 502A have solid state (include nuvistor) input stage, a 6DJ8 as the deflection amplifier and transistors as amplifiers and cathode followers (only in the newest version).
The 502 uses a single supply for the upper beam and lower beam CRT cathodes. The 502A has separate supplies for the two CRT cathodes. This improvement in the 502A allows slight differences in horizontal CRT sensitivity between the two beams to be canceled out in step 8 of the calibration procedure.
Links
- Tektronix 502A @ amplifier.cd (many internal pictures)
Pictures
502
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502 without Mod 104, front
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502 with Mod 104 (single sweep), front
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502 front view
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502 left
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502 right
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rubber shock mount of amplifier sub-chassis
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502 bottom
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502 trace
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502 trace
502A
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502A
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502A right internal
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502A right
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502A left
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502A rear
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Solid-state input stage with two 6DJ*
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502A vertical amp sn 25,997 to 30,999
RM502A
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RM502A
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RM502A rear
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RM 502A
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RM 502A display
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RM 502A bottom
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RM 502A transformer wiring
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RM 502A top
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RM 502A vibration-isolated vertical amp
Third version 502A, serial number greater than 31,000
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top side lower beam input amp and attenuator, bottom side of upper beam vert input board
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late model RM502A
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late model RM502A
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late model RM502A
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late model RM502A
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late model RM502A
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late model RM502A
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late model RM502A
Diagrams
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502A block diagram
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502A vertical amplifier
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502 CRT circuit
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502A CRT circuit
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Cartoon in schematic: Mountain Climber