21.
The oscillator
is
tuned
to
approximately
2,700
Hz
because
this
frequency is
a.
in the center of the voiceband.
b.
near the top of the voiceband.
c.
one to which the ear is most responsive.
d.
at resonance with the transformer secondary.
22.
Assume that you have checked the longitudinal balance of four input
circuits, and the respective calculations give 82 dB, 41 dB, 10 dB,
and 0 dB.
The wire pair having the best condition of longitudinal
balance is that pair which yields
a.
0 dB.
c.
41 dB.
b.
10 dB.
d.
82 dB.
23.
Assume that the normal power level of a test signal passing through
the output circuit is 0 dBm. When longitudinal balance of the output
circuit is checked, V2 is found to be 0.002 volt.
The longitudinal
balance of the output circuit is approximately
a.
58 dB.
c.
27 dB.
b.
52 dB.
d.
16 dB.
HINT:
V1 is 0.775 volt when signal level is 0 dBm.
SITUATION
Assume that you are measuring peak-to-peak phase jitter on the circuit
shown in figure 1-17.
You have calibrated the oscilloscope so that one
complete cycle (360) of the waveform display covers nine grid divisions on
the graticule.
Exercises 24 and 25 are based on the above situation.
45
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