Hitachi Model V-550B oscilloscope is a portable-type, advanced-class oscilloscope with a bandwidth of DC to 50MHz. Designed by putting special emphasis on operability and ruggedness, this oscilloscope has the following features: (1) Wide bandwidth: The instrument has a bandwidth of DC to 50MHz. (2) High sensitivity: Sensitivity is 1 mV/div. (3) Large 6M screen: Employment of a large square CRT makes waveforms easier to observe. (4) Internal graticule: Employment of internal graticule CRT permits waveforms observation to be made without parallax error. (5) Triple trace mode: Since the trigging signal can be observed on the CRT screen, the phase difference between CHI and CH2 input signals against external synchronizing signal can be measured. (6) TV synchronization: Employment of a new TV sync/separator circuit allows instrument to observe TV signals stably. (7) Delayed sweep: A portion of the signal can be magnified before observation. (8) Autofocus: Focussing shift is automatically corrected.