LESSON 4
FM TRANSMITTERS
SCOPE.....................................Operation
of
divider
and
automatic
frequency
control
circuits
(AFC);
analysis
of
circuits,
to
include the double-tuned, phase, and
pulse discriminators; circuit analysis of
complete FM transmitter.
CREDIT HOURS..............................2
TEXT ASSIGNMENT...........................TM 11-668, para 42-51;
Attached Memorandum, para 4-1 thru 4-5
MATERIALS REQUIRED........................None
SUGGESTIONS...............................Read the assignment in TM 11-668 and
review paragraphs 39-41 before you read
the attached memorandum.
LESSON OBJECTIVES
When you have completed this lesson, you will be able to:
1.
Analyze the operation of the different types of AFC circuits.
2.
State the purpose and explain the operation of frequency-divider circuits.
3.
Locate stages in an FM transmitter that perform specified functions.
4. Identify the frequencies and signals that appear at various points in an FM
transmitter.
ATTACHED MEMORANDUM
Section I.
FREQUENCY DIVIDERS
4-1.
SYNCHRONOUS DIVIDER
The frequency dividers of the type under consideration in this section produce a
sinusoidal voltage or current at a submultiple of the sinusoidal input frequency.
As indicated in the text, waveform devices such as multivibrators or counters can
be used, with filtering, to produce a sinusoidal output.
However, some
nonlinearity must be present to effect division.
As a practical matter, a
synchronous oscillator is usually involved in the
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