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.
|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)|
|Year||1959||1961||1963 (A)||1971 (A)|
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.
The 502 has a 123 °F (50.5 °C) thermal cutoff switch.
- Tektronix 502A @ amplifier.cd (many internal pictures)