5. In designing an FM receiver it is found that a weak signal is lost as a
result of a strong signal from an adjacent channel. The degree of this oscillator
frequency pulling can be reduced by
a. increasing the coupling of the RF amplifier.
b. isolating the mixer from the oscillator.
c. reducing the intermediate frequency.
d. applying AVC to the mixer grid.
6. Assume that the FM receiver whose circuit is shown in figure 152 of TM 11-668
has a frequency range of 20 to 30 MHz, but satisfactory reception is obtained only
in the frequency range of 20 to 25 MHz because of improper tracking.
Improved
reception can be achieved by adjusting
a. capacitor C29.
b. capacitors C27 and C28.
c. the capacitors located in T4.
d. the capacitors located in T1, T2, and T3.
7. When the mixer and oscillator in a superheterodyne receiver are tuned so that
a constant frequency difference is maintained between them, the oscillator is said
to be
a. pulling.
c.
radiating.
b. tracking.
d.
converting.
8. The function of a padder in a radio receiver is to
a. cause the RF signal to lock in with the oscillator.
b. increase the response of the mixer to high frequencies.
c. reduce the shot effect and partition noise in the receiver.
d. provide a tracking adjustment at the low end of the receiver band.
9. The VHF band nominally extends from 30 MHz to 300 MHz.
The types of
frequency transforming devices that may be used in an FM receiver designed to
operate around 300 MHz include the
b. diode mixer, push-push triode mixer, and crystal mixer.
c. pentagrid mixer, crystal mixer, and pentagrid converter.
d. push-push triode mixer, pentagrid converter, and pentagrid mixer.
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