Rf Output Impedance Matching And Output Buffer; Voltage References (5.7V And 6.4V); Figure 8-8. Output Amplifiers - HP 10811A Operating & Service Manual

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8-23. RF OUTPUT IMPEDANCE MATCHING AND OUTPUT BUFFER

8-24.

The signal for the output amplifiers is taken from the same point as the AGC (across C10). The

voltage is buffered by Q5 which is an impedance matching stage. Resistors R14 and R15 set the

dc bias level while C14 allows the ac to bypass R14. The signal is then applied to the output

buffer stage of Q9. Resistor R40 provides the 50Ω source impedance when transformed by T1.

Typical gain from Q9 base to collector is approximately 2. See

8-26.

Constant current diode CR2 feeds 1 mA to zener diode CR3 providing 6AV dc for the EFC

varactor reference. R12 and C15 form a filter to attenuate noise from the zener diode. R13

provides current limiting for Q5 if the 5.7V line is shorted. See

Model 10811A/B

Figure

8-8.

Figure

8-9.

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10811b