2001 Page 3
The Frequency Range Switch on the lower left side of the panel
indicates the particular dial calibration and multiplying factor
to use,
The Output Voltage is controlled by the volume control at the
right side of the panel. This control is situated in the circuit
between the oscillator and the output amplifier, When very small
audio voltages are desired, it is good practice to use an attenu-
ator between the oscillator and the equipment being driven. This
will aid in keeping the hum level far below the audio signal.
The Model 200i is designed to operate on 115 volts at 50 to 60
cycles per second. However, changes in line voltage of &O volts
will have very little effect on the instrument because of the volt-
age-regulator circuit incorporated,
Before leaving the factory, the instrument has been adjusted
to deliver mor than rated power into the rated load, Because of
this feature, the output wave may show some distortion when the
volume control is adjusted to give maximum output. This condition
is normal, and when low distortion is required, the oscillator
should be operated at rated output or slightly below.
IV. MAINTENANCE,
The total Harmonic Distortion is less than 1% if the instru-
ment is operating properly. When tubes are changed, the distortion
should be measured, because a poor tube will increase the distor-
tion without otherwise affecting the operation of the instrument.
Fuse is a 1 ampere cartridge located on the under side of
tho chass The Fuse close to the power cord, If the f'use fails, the instru-
ment should be carefully checked to ascertain the cause of overload,
Do not replace with a fuse of higher amperage, Never short the
clips on the fuse block.
Instability of the output voltage is sometimes caused by a
defectiv tube n the oscillator section. Therefore, if such a
condition arises, it will often save time to check these components.
first.
The Freauency Calibration will ordinarily remain constant with-
out adjustment. If necessary, however, the calibration of the
various bands ma be shifted slightly be adjusting the potentio-
meters R13 to R18 in the following manner: |