Synthesizer Operation; Monitoring The Synthesizer/Function Generator - Wavetek 171 User Manual

1.
2.
3.
For frequency control with positive de inputs at VCG
IN, set the dial for a lower frequency limit.
For frequency control with negative de inputs at VCG
IN, set the dial for an upper frequency limit.
For modulation with an ac input at VCG IN, set the
dial at the desired center frequency. Do not exceed
the maximum dynamic range of the selected frequency
range.
Figure 3-5 is a nomograph with examples of dial and voltage
effects. Example 1 shows that with OV VCG input, frequency
is as determined by the main dial setting, 1.0 in this example.
Example 2 shows that with a positive VCG input, output
frequency is increased. Example 3 shows 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
SETTING
2.0
1.8
1.6
1.4
1.2
1.0
-
"'
'
.8
.6
.4
.2
- -
' '
VCGIN
VOLTAGE
OUTPUT
FREQUENCY
FACTOR
.002
-2.0
-1.6
. 2
-1.2 .4
.6
- .8
""~\..~;..
~"/..~
-
- .4_.. .8
- 0
EXAMPLE 1
- -
-
1.0
+ .4 1.2
'
+ .8 1.4
'
1.8
+1.2
'~+
,~~
,:oo<
+1.6
~..?
1.6
' '
.002 +2.0 2.0
Figure 3-5. VCG Voltage-to-Frequency Nomograph
NOTE
Nonlinear operation results when the VCG input
voltage is excessive; that is, when the attempted
generator frequency exceeds the range setting
(2 times the multiplier setting) or in the other
direction, 1 /1000th of the range setting.
The up to 1000: 1 VCG sweep of the generator frequencies
available in each range results from a 2V excursion at the
3.4
VCG IN connector. With the frequency dial set to 2.0, ex-
cursions between -2V and OV at VCG IN provide the up to
1000: 1 frequency sweep. With the dial set to .002, excursions
between OV and +2V at VCG IN provide the up to 1000: 1
sweep within the set frequency range.
3.2.4
Synthesizer Operation
For synthesizer operation, select the waveform, frequency
and amplitude. The following steps demonstrate synthesizer
control. (Circled numbers are keys to figure 3-1.)
Step
2
3
4
5
6
7
Control/Connector
50f2 OUT or
6000 OUT
Dial/Digital Switch
Selector
@
FREQ MULT
Digital Switch
@
Waveform Selector@
DC OFFSET
AMPLITUDE and
ATTENUATION
Setting
Connect the circuit to
either output (refer to para-
graph 3.2.1 ).
Set toward digital switch.
Set to desired range of fre-
quency.
Set to desired frequency
within the range .
Set to desired waveform.
Set as desired. Limit wave-
form amplitude to prevent
clipping (see figure 3-4).
Select desired amplitude.
Synthesizer frequencies are normally referenced to an inter-
nal crystal oscillator. However, an external 1 MHz sine or
square
wav~erence
signal can be applied at REF IN; the
indicat~r
e
will light, indicating a proper external ref-
erence
in
use.
3.2.5 Monitoring the Synthesizer/Function Generator
Besides the 50f2 OUT and 600f2 OUT main generator out-
puts, the GCV OUT connector supplies a voltage propor-
tional to the generator frequency, the TTL OUT connector
supplies a TTL compatible pulse train at the generator fre-
quency, and the REF OUTsuppliesaTTLcompatible lMHz
pulse train.
The GCV OUT signal is used to drive the frequency axis of
an X-Y recorder or oscilloscope; the generator frequency
TTL OUT signal is used to synchronize other devices to the
generator or to drive TTL level inputs, and the REF OUT
signal is used to reference other 171 's to a master crystal
oscillator.