c. limiting the oscillator voltage to a value slightly higher than the fixed
bias voltage.
d. keeping the sum of the oscillator voltage and signal voltage slightly less
than the mixer bias.
7. Interaction between the local oscillator and the RF signal circuits causes
the frequency of the local oscillator to change.
This type of change in local
oscillator frequency is known as
a. fading.
c. tracking.
b. pulling.
d. conversion.
8. When a pentagrid mixer is used for frequency conversion (as in figure 177, TM
11-665), the RF signal and the signal from a local oscillator are applied to
separate grids in the mixer tube.
The signal from the oscillator is normally
applied to grid number
a. 1.
c. 3.
b. 2.
d. 4.
9. In the triode-hexode converter tube, the electron stream of the mixer section
is modulated at the oscillator frequency. The coupling between the oscillator and
mixer sections is accomplished by
a. interelectrode capacitance coupling.
b. electron stream coupling.
c. a mixer-injection grid.
d. cathode coupling.
10. In the pentagrid converter shown in figure 181 of TM 11-665, grid 2 has the
function of
a. accelerating the electron stream.
b. acting as an electrostatic shield.
c. acting as the plate of the oscillator.
d. isolating the oscillator from the RF signal.
11. To simplify frequency tracking in a receiver, the same size tuning capacitors
may be used for both the oscillator and the mixer. Frequency tracking in this case
is achieved by adjusting the
a. IF tuning capacitors.
b. mixer tuning capacitor.
c. oscillator tuning capacitor.
d. oscillator trimmer and padder capacitors.
322 L2
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