designed to amplify the audio signal without distorting it.
The driver
may be a single tube or two tubes in push-pull. The bias for the driver
is supplied by the driver rectifier. The signal from the driver is fed to
the modulator.
(2) Modulator.
This stage is used to provide the audio power needed to
modulate the RF power amplifier. The modulator may be a single tube, two
or more tubes in push-pull, or any even number of tubes in push-pull
parallel.
Any class of amplifier may be used.
The class of amplifier
used and the circuit arrangement will be determined by the power required
to modulate the RF amplifier, and the permissible distortion.
Bias for
this stage is supplied by the bias rectifier.
The output is fed to the
final power amplifier, where it is superimposed on the RF carrier and fed
to the antenna for radiation.
LESSON EXERCISES
In each of the following exercises, select the ONE answer that BEST completes
the statement or answers the question.
Indicate your solution by circling the
letter opposite the correct answer in the subcourse booklet.
SITUATION
Assume that you are attached to a signal unit that has received a shipment of
low-power radio transmitters for use in the field.
A schematic diagram of this
transmitter is shown in figure 133 of TM 11-665.
Exercises 1 through 6 are based on the above situation.
1. The oscillator tank circuit consists of coil L1 and capacitor
a. C1.
c. C4.
b. C3.
d. C6.
2. The function of capacitor C6 is to
a. balance the reactance of C4.
b. transfer the oscillator output to the antenna.
c. couple the oscillator output to the amplifier input.
d. neutralize the interelectrode capacitance of V2 to prevent oscillation.
3. Capacitor C2 serves as a common cathode return for two RF circuits.
These
two circuits include the
321 L4
36
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