GW Instek GAD-201G User Manual

Page 7

GAD-201G user manual

5. OPERATING INSTRUCTIONS

1) Power on

a. Set the POWER switch to “OFF” position.

Check zero setting—If offset, adjust the pointer to zero by using

a small screwdriver.

Set the POWER switch to “ON” position.

2) Before applying an input signal

The instrument would be damaged by any applied signal which has an

excessive input voltage larger than 350Vrms. Make sure the input

voltage of the signal is less than 350Vrms.

3) AC voltage measurement

a. The range will be selected automatically when a signal is

connected to the input terminal, and the corresponding pilot

lamps are lighting on.

b. The reading value is obtained above one third of scale of meter

at least.

4) The decibel scale

The numerals under the pilot lamps correspond to the decibel (dB)

scale that ranges from 0 to +50dB. The decibel numerals correspond

to the voltage scale that ranges from 1V to 300V. If the range indicates

300mV to 1mV, it is necessary to add -60dB to the mentioned decibel

value.

GAD-201G user manual

5) Distortion measurement

In order to reject the fundamental harmonics, the distortion meter is

required the adjustment of the notch filter frequency. The instrument

provides Automatic Level Control (ALC) and automatic

synchronization, but it is required to adjust the frequency for

continuous measuring function.

a. Use FREQUENCY RANGE selector to set the input basic

fundamental frequency range to :

× 1………………20Hz to 200Hz

× 10…………… 200Hz to 2kHz

× 100 …………. 2kHz to 20kHz

b. Use TUNING FREQ. knob (15), the push buttons “HIGH”(13)

and “LOW”(14) to minimize the reading value of the meter.

c. When the basic frequency of the input signal is equal to the

fundamental frequency, the lamps of the TUNING FREQ. is on.

Turn the knob to the left (the pilot lamp of “HIGH” is on) or to

the right (the pilot lamp of “LOW” is on) to increase or

decrease the fundamental frequency, then turn off two lamps.

d. Connect the oscilloscope to X/Y output terminal, when the

pointer of the meter indicates the full scale position on 100%

range, the Lissajous’ figures can be observe as shown on the

Fig. 3 (a) below.