Operation --
Plug the power cable of the Model 200D into a 115 volts, 50/60 cycles
power source and turn on the AC power switch. The instrument will begin to
operate as soon as the tubes have heated, but for maximum accuracy a warm-
up period of about 30 minutes is necessary.
Set the frequency dial and RANGE switch so that their indications, when
multiplied together, equals the desired frequency. For examplep if it is de-
sired to select an output frequency of 1000 cycles per second, set the frequency
dial to 10 and the RANGE switch to x10.
Connect the output of the oscillator to the equipment being driven and
adjust the AMPL. control for the desired output voltage.
Although the rated load for the Model 200D is 1000 ohms, higher or
lower impedance loads may be used without damage to the instrument. A higher
impedance load will result in less power output and a lower impedance load will
increase the percentage of distortion in the output voltage.
0
U
As the output voltage of the audio oscillator is reduced the percentage of
3
3 hum voltage will increase. At the lower levels this hum voltage becomes quite
3
large, relative to the sine wave output voltage. This undesirable condition can
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t-
be remedied by operating the audio oscillator at or slightly below rated output
+
cd and inserting a suitable attenuator between the oscillator and the equipment being
.A
k
?Q) driven by the oscillator. The voltage divider circuit shown next is satisfactory
cn for most applications.
EQUIPMENT
MODEL 200D BEING
OS GILL ATOR SUPPLIED
900 ohms
g--r-- 100 ohms
Other values af resistance may be used to obtain different voltage divisions.
In all cases, the sum of the divider resistors should match the rated load of 1000
ohms.
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