Wavetek 188, Instruction Manual

Page: 18 / 50

,
VCG and main
dial wfthin
a
frequency
range.
Linear
operation is selected when the
button
Is
extended. Logarithmic
operation is selected
when
the button
is
depressed.
8, 8 Generator MODE Controls
-
Selects
one
of
the
fol lowing
three modes:
CONT
-
8 released. Continuous output at
500 OUT 15 and 18 and SYNC OUT
(TTL)
17 connectors.
TAIG
-
8 and 9
pressed.
DC level
output
until generator triggered by the MAN TRIG 11
or with a
signal
at the TRIG I N connector 18 .
When
triggered, the
generator output is one cycle
of waveform
fol lowed by
a
dc
level.
GATE
-
8 pressed and 8
released .
As for
TRIG
except
the o
u
tpu
t
is continuous for the
duration of the manual
or external
trigger signal.
The last cycle started is
always
completed.
10 TIME Knob
-
Sets the
sweep
time by control­
ling the
period
of
the sweep ramp generator.
1 1 Manual Trigger Button
-
Triggers or gates
the
output
signals
when generator mode is TRIG
o r
GATE ( 8
pressed).
In trigger
mode,
one
wavefo rm
cycle
is output when the
button
is
pushed. In gate mode,
waveform c
y
c
les are con­
tinuously output
as
long
as
the
button
is held in.
12 FUNCTION Selector
-
Selects-
one
of three
waveforms
or
when
all
three
b
u
t
to
n
s are released,
a dc
level . .
1 3 DC OFFSET Control
-
Offsets the 500
OUT
waveforms or
gives dc levels
from -
1 0V
to
+
1 0V
(
-
5V
to
+
5V into
500)
at 15
and from
- 1 V
to
+
1 V
(
-
0.5V
to
+
0.5V
into
500) at
18.
An OFF position ensures
no
offset.
14 AMPLITUDE Control
-
Ccw
rotation reduces
waveform amplitudes at 1 5 and 16
by
30 d B . DC and offset voltages
are
not affected
by thi s control.
15 SOO OUT HI Connector
-
The
main
output
of
the generator at
the
function selected. Maximum
20
Vp-p (1 0 Vjrp
into
500)
with 30 dB continuous
ampl itude control . 500 sou rce
im
ped
ance.
18 500 OUT LO Connector
-
Same as 15 ex­
cept 20 dB
(1 /1 0)
lowe r
in
amplitude.
1 7 TIL OUT
Con nector
-
A TI L
square for
each
cycle
of the generator. To
be used fOr syn­
chronization
or
as
a TIL
signal capable
of
driv­
ing 20 TIL
loads .
1 8 TRIG IN Connector
-
Accepts a TI L
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.
18 SWP OUT Connector
-
Supplies
a
ramp
waveform with an approximate 4V
peak into
an
open circuit. For use as a
horizontal
drive
signal .
Source impedance is 6000.
20 GCV OUT Connector
-
Provides
a
0 to
4V
open
circuit
outp
u
t
proportional
to the
f requency
of the main generator. For
use as a
horizontal
drive
signal.
Source
impedance
is 6000.
21 VCG IN Connector
-
Accepts
ac
or dc voltages
to proportionately
control frequency within
the
range
determined by the FREQ U E NCY
M U LTIPLIER 4
.
Positive voltage increases the
frequency set by the dial 1
;
negative
voltage
dec reases
the frequency. The VCG IN will not
drive
the generator
frequency
beyond the
nor­
mal dial
limits of
a
range .
Input impedance
is
2 kO.
3.2 OPERATION
Perform the initial
checkout
in S
ec
t
i
o
n 2
for
the feel of
the
instrument. Any
questions
c o
n c
e
r n i
n
g
individual
controls a
n
d 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 p roper termination
of
either
of the
500 OUT
connectors
is shown in figure 3-2. Placing
the
500
terminator,
or 500
reSistance, in parallel
with
a higher impedance, matches the
receiving instru­
ment input impedance to
the
coax
characteristic and
gen erator output
impedance,
thereby
m'inimizing
signal reflection
or power
loss on the li
n
e
due to im­
pedance mi:;;match.
The
input
and output
impedances
of the
generato r
connectors
are
listed
below.
Scans
by
ArtekMedia
=>
2011