Model 201C Section 111
SECTION 111
OPERATING INSTRUCTIONS
3-1. CONTROLS AND TERMINALS. b. Turn the power switch ON and allow approximately
five minutes for the instrument to reach its normal
3-2. ON. Toggle switch controls line voltage to instrument. operating temperature.
3-3. RANGE. Three-position rotary switch selects various c. Set the FREQUENCY dial and RANGE switch for
values of resistance in the bridge circuit of the RC desired output frequency.
oscillator. The position of this switch indicates the
multiplying factor for the frequency dial calibration. d. Set ATTENUATION outer control to 0 dB, then set
inner control (amplitude) for desired output
34. FREQUENCY dial. This control varies the capacitance voltage.
in the bridge circuit of the RC oscillator to vary output
frequency between range switch steps. The dial is calibrated e. Set ATTENUATION outer control, if desired, to
from 20 to 200 and its indication multiplied by the factor reduce output level in 10 dB steps.
indicated by the RANGE switch will give the actual output
frequency of the oscillator. The small knob below the
frequency dial is a vernier control for thc dial. NOTE
When the attenuator is in the OdB
3-5. ATTENUATION. This is a dual concentric control. position the amplifier output is delivered
The inner control is a potentiometer which adjusts the from less than 600 ohms at frequencies
amplitude of the oscillator voltage admitted to the
amplifier, and therefore, it adjusts the output voltage of the below 5000Hz, and it will produce its
rated output (3 watts) across a load of
instrument from zero to a maximum value established by
the attenuator. The outer control is a bridged-T type 600 ohms. When the attenuator is
attenuator providing 0 to 40 dB of attenuation in 10 dB positioned for 20 dB or more
steps. attenuation, the internal impedance is
600 ohms.
3-6. OUTPUT terminal. Two binding posts on the lower
center of the front panel are the output terminals for the
oscillator. Terminal marked G is connected to the chassis of 3-8. LOW LEVEL APPLICATIONS.
the instrument.
3-9. To avoid excessive noise and hum at low output levels
3-7. OPERATING INSTRUCTIONS. (40 dBm or less), it it good practice to attenuate the
oscillator output -30 or 40 dB and use the amplitude
a. Connect the power cable to required power source. control as an output vernier to obtain desired level.
3-1 |
ACEC
