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8
DC OFFSET
Control
—
Offsets the
500
OUT
waveforms
or
gives
dc
levels
from
-10V
to
+
1
0V
(
-
5V
to
+
5V
into
508)
at
1
and
from
-1V
to
+1V
(-0.5V
to
+0.5V
into
500)
at
11
.
An
OFF
position
ensures no
offset.
9
AMPLITUDE
Control
—
Ccw
rotation
reduces
waveform
amplitudes
at
10
and
11
by
30
dB.
DC
and
offset
voltages are
not affected
by
this
control.
10
500
OUT
HI
Connector
—
The main
output
of
the generator
at
the function selected.
Maximum
20V
p-p
(1
OV
p-p
into
500)
with
30
dB
continuous
amplitude
control.
500
source impedance.
11
500
OUT
LO
Connector
—
Same
as
10
ex-
cept
20
dB
(1/10)
lower
in
amplitude.
12
TTL
OUT
Connector
—
A
TTL
square
for
each
cycle
of
the generator.
To be used
for
syn-
chronization or
as a
TTL
signal
capable
of
driv-
ing
20
TTL
loads.
13
TRIG
IN
Connector
—
Accepts
a
TTL
signal
to
trigger
or
gate the generator. Triggers
on
the
ris-
ing
(low
to high) transition
and
gates
during the
positive (high) portion of
the
triggering
signal.
14
VCG
IN
Connector
—
Accepts ac
or
dc
voltages
to
proportionately control
frequency
within the
range
determined
by
the
FREQUENCY
MULTIPLIER
3
.
Positive
voltage increases the
frequency
set
by
the
dial
1
;
negative voltage
decreases
the frequency.
The
VCG
IN
will
not
drive the
generator frequency
beyond
the
nor-
mal
dial limits
of
a
range. Input
impedance
is
2kO.
3.2
OPERATION
Perform
the
initial
checkout
in
Section
2
for
the
feel of
the instrument.
Any
questions concerning
individual
controls
and
connectors
may
be
answered
in
paragraph
3.1.
3.2.1
Signal
Termination
Proper
signal termination, or loading, of
the generator
connectors
is
necessary
for
its
specified operation.
For example, the proper
termination
of either of
the
500
OUT
connectors
is
shown
in
figure
3-2.
Placing
the
50
ohm
terminator, or
50
ohm
resistance,
in
parallel
with
a
higher
impedance,
matches
the
receiv-
ing
instrument
input
impedance
to
the
coax
characteristic
and
generator
output
impedance,
thereby minimizing
signal reflection or
power
loss
on
the
line
due
to
impedance
mismatch.
The
input
and
output
impedances
of
the
generator
connectors
are
listed
below.
Connector
Impedance
50QOUT(HI)
500
500
OUT
(LO)
500
SYNCOUTfTTL)
*
TRIG
IN
*
VCG
IN
2k0
•The
TTL
OUT
connector
is
diode protected
and can
drive
up
to
20
Transistor-Transistor-Logic (TTL) loads
(low
level
between
OV
and
0.4V,
and
high
level bet-
ween
2.4V
and
5V).
It
should
not
be conencted
to
resistive
load
less
than 6000.
The TRIG
IN
connector
accepts
TTL
logic levels,
is
diode
protected,
and
re-
quires
500
/tA
drive
from a
high
level
output.
MODEL
182
A
RECEIVING
INSTRUMENT
RG58
0R
EQUIVALENT
50Q
rs
.
LOAD
EFFECTIVE
CIRCUIT
RESISTANCE
1
-AW
—
(SIGNAL
LOAD)
>50Q
Figure
3-2.
Signal
Termination
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.
(Bold
numbers
are keys
to figure
3-1
.)
Step Control/Connector
Setting
1
500
OUT
10
11
Connect
circuit to either
output
(refer
to
para-
graph
3.2.1).
2
FREQUENCY
Set
to
desired range
of
fre-
MULTIPLIER
3
quency.
3
Frequency
Dial
1
Set
to
desired
frequency
within
the range.
4
FUNCTION
7
Set
to
desired
waveform.
5
DC
OFFSET
8
Set as
desired.
Limit
wave-
form amplitude
to
prevent
clipping
(see
figure
3-3).
6
AMPLITUDE
9
Select
for
desired ampli-
tude.
3-2
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