c. adjust the bias on tube V4.
d. establish the AVC delay threshold.
9. The reason that transformer T5 is center-tapped is
a. so the signal applied to the grids of V5 and V6 will be in phase.
b. so the signal applied to the grids of V5 and V6 will be 180 out of phase.
c. to provide
cross-neutralization
and
prevent
oscillation
in
the
power
amplifier.
d. to provide feedback from the plates of V5 and V6 to the grids to sustain
oscillation.
10. A repairman who is working on the receiver that is represented by the
schematic in figure 206 should be able to identify the bleeder resistor as resistor
a. R14.
c. R19.
b. R16.
d. R24.
11. It is virtually impossible to tune a receiver entirely by ear because the AVC
circuit tends to maintain a constant output from the speaker. However, a dc meter
connected in series with the plate of the AVC controlled circuit (IF or RF, or
both) can serve as a tuning indicator.
When the receiver is properly tuned, the
meter will indicate
a. maximum plate current.
c. maximum plate voltage.
b. minimum plate current.
d. minimum plate voltage.
12. The detector used in an AM radio receiver cannot be used to receive CW
signals because the
a. average value of the rectified signal current is zero.
b. direct current resulting from rectification of a CW wave does not produce
an audible tone.
c. audio component is lost as the signal passes through the extremely narrow
bandpass tuned circuits.
d. rectified negative signal peaks cause the direct current to flow in the
direction opposite to normal.
13. Most communication receivers are capable of receiving CW signals as well as
voice and tone signals. To be able to receive CW signals, the receiver shown in
figure 206, TM 11-665, will require the addition of a
a. crystal-filter circuit inserted in the IF stage.
b. beat-frequency oscillator to mix with the IF signal.
322 L5
44
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