Wavetek 188 - Page 14

exceed
the limits of the selected frequency
range
Figure
3-4
is
a
nomograph with examples
of
dial
and
voltage effects. Example 1 shows that with
OV VCG
in-
put.
frequency is determined
by
the main dial setting.
2
(linear mode) or
04
(logarithmic mode) In this exam-
ple. Example
2
shows that with a positive VCG input,
output frequency is increased Example
3
snows that
with a negative VCG input, output frequency is
decreased
(Note that the Output Frequency
Factor
column value must
be
multiplied
by a
frequency range
multiplier
to
give the actual
output
frequency
)
MAIN DIAL
VCO IN
OUTPUT
SETTING VOLTAGE FREOUENCV
FACTOR
Figure
3-4.
VCG Voltage-to-Frequency Nomograph
The
up to
1000:1 (linear) or 10.000:1 (logarithmic) VCG
sweep of the
generator
frequencies
available
in
each
range
results from
a 4V
excursion
at
the
VCG
IN con-
nector With the frequency dial
set
to 4.0. excursions
between
-
4V and 0V at VCG IN provide the up to
1000.1 (lm) or 10.000:1 (log) frequency sweep.
With
the d>ai set to .004
(linear)
or 0004
(logarithmic),
ex-
curs ons between 0V
and
+ 4V at the VCG IN
provide
up to 1000:1
(linear) or
10.000:1
(logarithmic sweep
within
me set
frequency range
3.2.4 Sweep
Generator Operation
Operation
as a
sweep generator is similar to manually
controlled generator operation except the main
generator can
be
repetitively swept between two
selected frequencies either linearly or logarithmicly at
a
selected sweep rate
The relationship of internal
ramp and mam generator is shown in figure 3*5.
The
io*Ow»ng
steps
describe the sweep operation
setup
GCV
OUT
soo
OUT
8TOP
FREO
LEVEL
START
FREO
LEVEL
STOP FREQ
CONTROL
NOTE
Nonlinear operation may result when the
VCG input voltage is excessive, that is.
when the attempted generator frequency
exceeds the
range limits. The upper limit is
four
times the multiplier setting, and the
lower limit is 1/IOOOth (linear) or UtO.OOO
(logarithmic) of the upper limit
Figure 3-5. Effect of Sweep Time and Width
on Output Frequency
Step Control Setting
1 MOOE: CONT
8
Press
to
release
(Continuous mode of
main
generator
is
necessary for
sweep
)