The Horizontal Amplifier circuit, shown on Diagram 7, provides the output signals that drive the horizontal crt deflection plates. Signals applied to the Horizontal Preamplifier can come from either the Miller Sweep Generator (for sweep deflection) or from the XY Amplifier (when X-Y display mode is selected). See Figure 3-7 for a detailed block diagram of the Horizontal Amplifier circuit.

The Horizontal POSITION control, X10 magnifier circuitry, and the horizontal portion of the beam finder circuitry are also contained in the Horizontal Amplifier circuit.

Horizontal Preamplifier

The sum of the sweep and positioning current is applied to the input of one side of a differential amplifier composed of Q730 and Q731. For all conditions other than the X-Y Mode, XY Switch transistor Q720 is biased on to provide a ground reference at the other input of the differential amplifier (at the base of Q731). The output of the differential amplifier, taken from the collector of Q731, is amplified by Q736.

A feedback network connected between the output of Q736 and the base of Q730 provides the circuitry required for the X10 magnification feature. In the unmagnified mode, X10 Magnifier switch S734 is closed and the feedback is provided by the paralleled combination of R732 and C732. Resistor R732 sets the unmagnified amplifier gain and C732 provides the HF compensation.

When the X10 Magnifier push button is pressed in, S734 opens and additional components are added to the feedback network. With the feedback reduced, the amplifier gain is increased by a factor of 10. The X10 Gain potentiometer (R733) is adjusted to produce the exact gain required. High-speed linearity compensation of the feedback network is provided by adjustable capacitor C734.

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