By depressing the START-STOP button a second time, the filter will
stop on it’s current frequency. If the filter is left running in the
AUTO mode when it reaches the highest centre frequency, it will re-
main there until the reset button is depressed.
Ranging Buttons and LED Indicators
The range of the instrument is indicated by a series of five LED’s.
To change the range ‘up’, depress the button marked with an up ar-
row, to change the range ‘down’, the button marked with a down ar-
row is depressed. The five base ranges on the GA112 are shown be-
low (figure 3).
Figure 3 – Table of available ranges
As can be seen from the table above, a 10dB overlap occurs between
the ranges, this means that if a meter reading in the bottom ‘third’ is
observed the range can be changed down.
Generally it is better to select a range which gives you the greatest
deflection on the meter. However if the meter reading passes full-
scale deflection, or the overload LED (found in the lower right cor-
ner of the meter) indicates an overload, the instrument must be
changed up a range.
Base range
Meter range
30dB
30-60dB
50dB
50-80dB
70dB
70-100dB
90dB
90-120dB
110dB
110-140dB
GA112
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Summary of Contents for GA112
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