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continually. But if the amplitude of signal is small in the attenuation of 0dB, the
distortion of waveform will be larger and the signal-to-noise ratio is worse.
3.2.6 Output load： The setting value of amplitude is calibrated when the output
end is open. The real voltage of output load is the setting value of amplitude
multiplied by the assignment ratio of load resistance and output resistance. The
output resistance is about 50Ω. When the load resistance is big enough, the assignment ratio
approaches to 1. The voltage loss of output resistance can be neglected. The real
voltage approaches to the setting value of amplitude. But when the load resistance is
smaller, the voltage loss of output resistance cannot be neglected. It should be paid
more attention that the real voltage does not accord with the setting value of
amplitude.
Output of channel A has over-voltage protection and over-current protection. Several-
minute short circuit or reverse voltage of less than 30V will not lead to any obvious damage.
Nevertheless, the above cases should be avoided in case of potential damage for the generator.
3.2.7 Flatness of amplitude： For the output frequency less than 1MHz, the
amplitude of output signal is very flat. For the output frequency greater than 10MHz,
the matching characteristics of output amplitude and load will lead to the worse
flatness. The maximum output flatness will be limited too. Generally speaking, the
maximum output flatness is only 15Vpp if the output frequency is greater than
15MHz and the maximum output flatness is just reach to 8Vpp if the output
frequency is greater than 20MHz. The larger the output amplitude is, the bigger the
distortion of the waveform is.
3.2.8 Setting of offset of channel A： In some cases, certain DC component should
be contained in the AC signal to be output so as to produce DC offset. Press the key
of【 Offs 】 and select “ Offset of channel A”. The present offset value will be
displayed. Use the numeric keys or the knob to enter the offset value. The preset DC
offset will be produced from the output of channel A.
It must be paid attention that the summation of the half of the output amplitude
of signal and the absolute offset value should be less than 10V to guarantee the peak
value of signal less than ±10V. Otherwise, the amplitude-limited distortion will be
induced. Besides, when the attenuation of channel A is selected auto, the output
offset will attenuate with the attenuation of amplitude. For the Vpp of amplitude
greater than 2V, the real output offset is the set offset value. For the Vpp of
amplitude greater than 0.2V but less than 2V, the real output offset is tenth of the set
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