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.

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1 MHz dual beam differential scope
Tek 502 front (with Single Sweep Mod 104)

Produced from 1958 to 1973

Manuals

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
2018 value $7,070 $6,890 $8,560 $7,790

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

Pictures

502

502A

RM502A

Third version 502A, serial number ≥31,000

Diagrams