It has two electron guns and two pairs of vertical deflection plates, but common horizontal deflection plates.
The improvement over the T57 was to support a horizontal beam registration circuit that allows to compensate for stray fields in order to make the starting times of both beams coincide.
- Tektronix T5511P Technical Data (PDF, needs OCR)
- Tektronix T5511 CRT Data, Rev A (PDF, OCR)
- Tektronix T5511 Performance Data (PDF, OCR)