Operation - Wavetek 188 Manual

VCG and main dial within a frequency range.
Linear operation is selected when the button is
extended. Logarithmic operation is selected
when the button is depressed.
8, 9Generator MODE Controls — Selects one of
the following three modes:
CONT — 8 released. Continuous output at
500 OUT 15 and 16 and SYNC OUT (TTL)
17 connectors.
TRIG — 8 and 9 pressed. DC level output
until generator triggered by the MAN TRIG 11
or with a signal at the TRIG IN connector 18 .
When triggered, the generator output is one cycle
of waveform followed by a dc level.
GATE — 8 pressedand 9 released. As for
TRIG except the output 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.
11 Manual Trigger Button — Triggers or gates the
output signals when generator mode is TRIG or
САТЕ (8 pressed) |п trigger mode, one
waveform cycle is output when the button is
pushed. In gate mode, waveform cycles are con-
tinuously output as long as the button is held in.
12 FUNCTION Selector — Selects one of three
waveforms or when all three buttons are released,
a dc level.
13 DC OFFSET Control — Offsets the 500 OUT
waveforms or gives dc levels from — 10V to
+ 10М (-5V to + 5V into 500) at 15 and from
—1V to +1V (—0.5V to +0.5V into 500) at 16.
An OFF position ensures no offset.
14 AMPLITUDE Control — Сем rotation reduces
waveform amplitudes at 15 and 16 by
30 dB. DC and offset voltages are not affected
by this control.
15 500 OUT HI Connector — The main output of
the generator at the function selected. Maximum
20 Vp-p (10 Vp-p into 500) with 30 dB continuous
amplitude control. 50Q source impedance.
16 500 OUT LO Connector — Same as 15 ex-
сері 20 dB (1/10) lower in amplitude.
3-2
17 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. :
18 TRIG IN Connector — Accepts а 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.
19 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 600Q.
20 (СУ OUT Connector — Provides a 0 to 4V
open circuit output proportional to the frequency
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 FREQUENCY
MULTIPLIER 4 . 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
2 kQ.
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 50Q terminator, or 50Q resistance, in parallel with
a higher impedance, matches the receiving instru-
ment input impedance to the coax characteristic and
generator output impedance, thereby minimizing
signal reflection or power loss on the line due to im-
pedance mismatch.
The input and output impedances of the generator
connectors are listed below.