Output Amplifier - Wavetek 193 Instruction Manual

4-1
Figure 4·1. Model 193 Overall Block Diagram
AMPLITUDE MODULATION/SUPPRESSED CARRIER OPERATION
I
I
~- __ -- __ ~I
...
CARRIER
SIGNAL
MAIN
GENERATOR
1--__
FUNC
OUT
SWEEP/MODULATION
GENERATOR
I OUTPUT
J
AMPLIFIER
~----I .... ~
(PART OF
AM
I
MAIN
SIGNAL I GENERATOR
1 _'
SWEEP/FREQUENCY MODULATION OPERATION
FUNC
OUT
IN
SWEEP/MODULA TION
...
MAIN
GENERATOR
..
GENERATOR
SWEEP/
FM
4.2 MAIN GENERATOR BLOCK DIAGRAM
ANALYSIS
As shown in figure 4-2, the VCG (Voltage Controlled
Generator) sums the voltage inputs from the FREO/
START FREO Dial, VCG IN, sweep/FM input and fre-
quency vernier to provide a voltage control signal for
the positive and negative current sources and the
GCV amplifier. The positive and negative current
sources generate precision currents, linearly related
to the output of the VCG summing amplifier, which
pass through the current switch to the timing capaci-
tors. Additional linear currents are generated for loop
dc delay compensation and the trigger baseline com-
Figure 4-2 illustrates the Main Generator circuit
elements and their functional relationships, which
paragraphs 4-2 and 4-4 describe. Figure 4-3 shows
the Sweep/Modulation Generator circuit elements
and their functional relationships, which paragraph
4-3 and 4-5 describe.
SECTION
4
CIRCUIT DESCRIPTION
4.1 INTRODUCTION
The Model 193 consists of two completely seperate,
independent function generators: the main generator
and sweep/modulation generator. This section
describes the functional relationship between the two
generators, and the function and relationship of the
major circuit element of each generator.
While each generator can operate independently,
they can be interconnected for frequency sweep, fre-
quency modulation (FM), doubleside band amplitude
modulation, and suppressed carrier amplitude
modulation (refer to figure 4-1). For sweep and FM,
the sweep/modulation generator varies the frequency
of the main generator. In AM, both suppressed carrier
and double side band, the main generator supplies a
carrier signal that mixes, on the sweep/modulation
generator board, with the modulating signal, created
by the sweep/modulation generator, to produce the
amplitude modulated signal which feeds back to the
main generator output amplifier.