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3.2.
OPERATION
3.2.1.
Setting the voltage at socket OUTPUT
By means of the control AMPLITUDE, the amplitude of the output signal is continuously variable.
Released button DC and pulled button PUSH FOR ZERO enables a continuously adjustable positive or negative
d.c. voltage to be added to the output signal.
When pressing the button DC, the a.c. part of the output signal is switched off and the d.c. voltage only is
fed to the output.
With step attenuator ATTENUATION, the output signal and the DC offset can be attenuated in steps of 10 dB
up to 60 dB. For 10 dB to 30 dB separate push buttons an:J available. Attenuations of 40 and 50 dB are selected
by combined pushbutton actions.
For 60 dB all three buttons have to be pressed.
Note:
The output amplifier could be overdriven due to adding signal and DC offset voltage. To avoid limiting,
the peak value of the open-circuit output voltage must not exceed± 15 V (step attenuator set to 0 dB).
3.2.2.
Setting the frequency
Three controls are provided for setting the frequency
dial with logarithmical scale
range selector"'F R EQUENCY Hz
vernier FREQ OFFSET control.
The scale reading, multiplied by the factor of the range selector, represents the frequency. In addition the
frequency deviation set by means of the FREQ OFFSET control must be accounted for.
The set frequency represents:
the output signal frequency
the signal frequency with
0 V control voltage at socket
SWP VOLTAGE IN/OUT
the start frequency
3.2.3.
Internal single sweep
when button SG LE SWEEP released
when button SGLE SWEEP pressed
of the single sweep mode.
Internal single sweep from the start-to the stop-frequency
is started by pressing the button SGLE SWEEP.
The characteristic is expontential following the relation
to= fSTART. 10 Uc/V
where f
0
=instantaneous signal frequency at the output
fsTART =frequency at the beginning of the sweep represented by the frequency setting, see 3.2.2.
Uc
= voltage at the socket SWP VOLTAGE IN/OUT.
So a control voltage difference of 1 V results in a frequency ratio of 10:1.
At the end of the sweep the output remains at the stop frequency which can be set by the SWP STOP/START
control. Resetting the SGLE SWEEP button effects the frequency to fly back to the start frequency. The sweep
time is adjusted by the SWP PERIOD potentiometer.
Pre-adjustment of the stop frequency may be performed at the end of the sweep with minimum period, prior
to setting the final sweep operation.
Please note:
The sweep can only be performed within the concerning sub-range. So it is obvious, that the SWP
STOP/START control must only be set to a value not exceeding the upper frequency of the sub-range
(e.g. 20kHz in II), see example 1 of the figure. Only if the start frequency is the lower limit of the sub-
range (e.g. 10Hz in II, example 2), the maximum sweep range of 2000:1 can be made use of. Settings
in examples 3 and 4 lead to overdriving, which besides of frequency limiting results in general distor-
tion of the signal.
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