c. grid-leak type of detector in place of the diode detector.
d. high-frequency heterodyne oscillator to mix with the RF carrier.
14. When receiving CW signals, the operator must switch off the AVC circuit so as
to prevent
a. zero beat.
b. receiver detuning.
c. changes in the audio pitch.
d. reductions in receiver sensitivity.
15. Assume that the receiver shown in figure 206, TM 11-665, has no output from
the speaker.
Using signal substitution, you have localized the trouble to the
first AF amplifier stage.
Voltage measurements show that the voltage applied to
the plate of V4 is zero. A possible cause of this trouble is
a. an open C30.
c. a shorted R21.
b. a shorted L2.
d. an open T5 primary.
16. The receiver shown schematically in figure 5-1 (attached memorandum) contains
an AVC circuit.
The voltage that is used to compensate for changes in signal
strength is developed across
a. capacitor C15.
c. resistor R10.
b. resistor R13.
d. resistor R9
17. Assume that you are about to troubleshoot an inoperative radio receiver. The
first step to locate the trouble, and possibly avoid many future troubles, is to
perform
a. an analysis of key circuits.
b. an operational check.
c. a visual inspection.
d. signal substitution.
18. Assume that you are troubleshooting a radio receiver and you discover a blown
fuse. This could have been caused by
a. an open bleeder resistor.
b. a shorted diode detector.
c. an open audio output transformer.
d. a shorted power transformer winding.
322 L5
45
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