When sourcing a CRT (Cathode Ray Tube) oscilloscope, the most critical factor is the Bandwidth (typically 20MHz to 100MHz), which determines the maximum frequency signal the device can accurately measure. You must also evaluate the Rise Time, as it should be significantly faster than the signal's fastest transition. For multi-signal analysis, ensure the unit has at least Dual Channels (CH1 & CH2) with an Add/Subtract algebraic mode. Additionally, check the Vertical Sensitivity (e.g., 5mV to 5V/div) and Sweep Time (e.g., 0.1uS to 0.2S/div) to ensure the display resolution meets your specific waveform analysis requirements.