Wavetek 171 - Page 12

3.2
OPERATION
Step
Control
/Connector
Setting
Operation
is
described
as
function
generator
operation and
synthesizer
operation.
The generator
is ready to
operate
as
soon
as a frequency
multiplier
is selected.
3.2.1
Signal
Termination
Proper
signal termination,
or
loading,
of the generator con-
nectors
is necessary
for its
specified
operation. For
example,
the
proper termination
of the
500
OUT connector
is
shown
in
figure
3-3.
Placing
the 50 ohm
terminator, or
50
ohm re-
sistance,
in
parallel
with
a higher
impedance, matches
the
receiving
instrument
input impedance
to
the generator out-
put impedance,
thereby
minimizing signal
reflection or power
loss
on
the line due
to impedance
mismatch.
RECEIVING
MODEL
171
INSTRUMENT
Figure
3-3.
Signal
Termination
The
input and
output impedances
of
the generator
connec-
tors are
listed below:
Connector
Impedance
500 OUT
500
6000
OUT
6000
TTL
OUT
*
REF
OUT
*
VCG IN
2 kO
GCV
OUT
6000
REF IN
5
kO
*The TTL
OUT connector can
drive up
to
20 Transistor-
Transistor
Logic (TTL)
loads (low level
between
0V and
0.4V, and
high
level
between
2.4V and
5V). REF
OUT can
drive
up
to 3
TTL
loads. Addition
of the TTL
buffer option
gives
these
outputs the
capability of driving
a 500 load.
3.2.2
Manual Function
Generator
Operation
For
basic operation, select
the waveform
frequency
and
amplitude. The
following
steps demonstrate
manual
control
of
the function generator.
(Circled
numbers
are keys
to
figure 3-1.)
500 OUT or
6000 OUT
Connect
circuit to either
output
(refer
to
para-
graph
3.2.1).
Dial/Digital Switch
Selector
(
5
)
Set toward the dial.
FREQ
MULT
Set
to desired range of
fre-
quency.
Frequency
Dial (l)
•Set to desired frequency
within
the range.
Waveform
Selector
(6)
Set
to desired
waveform.
DC OFFSET
Set
as desired. Limit wave-
form
amplitude
to prevent
clipping
(see figure
3-4).
AMPLITUDE
and
ATTENUATION
Select for
desired
ampli-
tude.
TRIANGLE
WAVEFORM
INTO A
MATCHED
LOAD
+5V
—
5V
—
EXCESSIVE
POSITIVE
OFFSET OR
LOADING
EXCESSIVE
NEGATIVE
OFFSET
OR
LOADING
Figure
3-4.
DC OFFSET
Control
3.2.3
Voltage
Controlled
Function
Generator Operation
Operation as
a
voltage
controlled
function generator (VCG)
is
as for
a manually
controlled
function generator,
only the
frequency
within particular
ranges is
additionally controlled
with
dc levels
(±2V excursions)
injected
at the VCG
IN
con-
nector. Perform
the
steps
given in
paragraph
3.2.2,
only set
the frequency
dial to determine
a
reference
from
which
the
frequency
is
to be
voltage
controlled.
3-3