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 |
| 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
- Tektronix 502A @ amplifier.cd (many internal pictures)
- Tektronix 502A internals @ youtube (German)
Pictures
502
-
502 with (single-beam) X-Y display
-
502 Mod.104 (single sweep), front
-
502 Mod.104 (single sweep), front from lower left
-
502 left interior
-
502 right interior
-
rubber shock mount of amplifier sub-chassis
-
502 bottom
-
502 trace
-
502 trace
-
502 front panel without knobs
-
502 power supply section in operation
502A
-
502A
-
502A right internal
-
502A right
-
502A left
-
502A rear
-
Solid-state input stage with two 6DJ*
-
502A vertical amp sn 25,997 to 30,999
RM502A
-
RM502A
-
RM502A rear
-
RM 502A
-
RM 502A display
-
RM 502A bottom
-
RM 502A transformer wiring
-
RM 502A top
-
RM 502A vibration-isolated vertical amp
Third version 502A, serial number ≥31,000
-
top side lower beam input amp and attenuator, bottom side of upper beam vert input board
-
late model RM502A
-
late model RM502A
-
late model RM502A
-
late model RM502A
-
late model RM502A
-
late model RM502A
-
late model RM502A
