The Model 427 is a general purpose oscilloscope employing advanced, high-quality circuit techniques refined and cost-reduced through years of development work by EICO. While low-priced enough for beginners, the Model 427 has all the control facilities and performance quality demanded in general laboratory work, production testing, audio and ultra-sonic development and servicing, ham shacks, and advanced home workshops. Rugged, simple mechanical construction, plus clean open circuit layout make this scope easy to build even by a novice. 1-1 FEATURES 1. Vertical amplifier direct-coupled for minimum phase distortion, and push-pull for maximum linearity, throughout (6 stages in 3 push-pull pairs). 2. Choice of direct or capacitive input coupling. 3. One internal bias adjust, and a dc balance adjust on the panel, for simple adjustment to optimum performance. 4. Four-position (plus CAL) frequency compensated vertical input attenuator. 5. Saw-tooth (15V p-p, adjustable by HOR GAIN control) output jack on panel for connection to vertical input jack when adjusting the frequency compensation trimmers. 6. INTENSITY, FOCUS, and ASTIGMATISM controls on the front panel. 7. Sharp, clean trace-free of blooming. 8. Instantaneous, drift-free positioning permits centering any part of a trace expanded to 30cm vertically or 20cm horizontally. 9. Easy, direct connection to vertical deflection plates without need of removing and replacing shorting links or wires. Test leads are simply plugged into rear jacks, and switch turned from AMPLIFIER to DIRECT PLATES. 10. INTENSITY MODULATION input (2 meg input Z approx. , 20V ms for blanking beam).