Wavetek 193 Instruction Manual page 22

3.2.3 Voltage Controlled Main Generator
Operation
Operation of the main generator as a voltage controlled
function generator (VCG) is as for a manually con-
trolled function generator, only the frequency within
particular ranges is additionally controlled by an
external voltage (± 5V excursions) injected at the
VCG IN connector. Perform the steps given in para-
graph 3.2.2, only set FREQ/START FREQto determine
a reference from which the frequency is to be voltage
controlled:
1. For frequency control with positive dc inputs at
VCG IN, set the dial for a lower frequency limit.
2. For frequency control with negative dc inputs at
VCG IN, set the dial for an upper frequency limit.
3. For modulation with an ac input at VCG IN, set
the dial at the desired center frequency. When
applying VCG voltage, do not exceed the max-
imum dial range of the selected frequency
range.
Figure 3-6 is a nomograph with examples of dial and
voltage effects. Example 1 shows that with
oy
VCG
input, frequency is determined by the dial setting, 1.0
in this example. Example 2 shows that with a positive
As an actual exercise in operation, perform steps 1
through 13 in table 2-1.
OUTPUTATTEN 17 9
DC OFFSET 14,
Inner Control12
8
6 FREQ/ST ART FREQ
Dial 1
7 FUNCTION 12
3 MODE 9
4
SYM 7
5 FREQ MULT 5
Connect to under test
(refer to paragraph
3.2.1).
Select CONT.
Extended.
Set to desired range of
frequency
Set to desired frequen-
cy within the range.
Select desired wave-
form.
Set as desired. Limit
offset to prevent clip-
ping (See figure 3-3).
Select for desired at-
tenuator range.
Setting
Select AUX GEN OFF.
Step Control/Connector
AUX GEN
MODE 20
2 FUNC OUT 15
3-4
3.2.2 Manual Main Generator Basic Operation
The following steps demonstrate setting up the main
generator for continuous operation. (Bold numbers
are keys to figure 3-1. Refer to paragraph 3.1 for fur-
ther explanations of controls and connectors.) Out-
puts are shown in figure 3-5.
Connectors Impedance
FUNC OUT 500
SYNC OUT 500
GCV OUT 6000
AUX OUT 6000
AUX SYNC OUT TTL
TRIG IN 1.5kO
VCG IN 10kO
AM IN 6000
AUX VCG IN 11kO
The input and output impedances of the generator
connectors are:
Figure 3·4. Signal Termination
OUTPUT
IMPEDANCE
500
EFFECTIVE
CIRCUIT
RESISTANCE
RG58 OR
EQUIVALENT
~
RECEIVING
INSTRUMENT
MODEL 193
3.2.1 Signal Termination
Proper signal termination, or loading, of the generator
connectors is necessary for its specified operation.
For example, figure 3-4 shows proper termination of
the FUNC OUT connector. Placing the 500 termina-
tor, or 500 resistance, in parallel with a higher imped-
ance, matches the receiving instrument input imped-
ance to the coax characteristic and generator output
impedance, thereby minimizing signal reflection or
power loss on the line due to impedance mismatch.
controls and connectors may be answered in
paragraph 3.1.