GVT-427B User Manual
4
Introduction
GVT-427B is versatile AC voltmeter which is able to measure AC
voltage from ranges of 10 Hz to 1 MHz with full scale ranges from
300
µ
V to 100 V. The dB scale measures 1V as 0dB and ranges from
-90 dB to +41 dB. The 600
Ω
(1mW) dBm scale ranges from -90 dBm
to +43 dBm.
The scales on the meter are graduated up to 1.1 (for +1dB) and these
extended scales are especially useful when measuring the
characteristics of audio amplifiers. In addition, both instruments can
give AC voltage output of approximately 0.1V in full scale from the
output terminals, and the measurements can therefore be monitored.
GVT-427B is a two channels voltmeter with isolated output for each
channel which enables it to be used as a two channels preamplifier.
GVT-427B User Manual
5
Preliminary Notes
1.
Chassis grounding terminal:
Make sure the chassis ground terminal is connected to the earth
before inserting the power plug into the main supply.
2.
Maximum input voltage:
The voltmeter may be damaged if any input voltage exceeding
the specified voltage is applied to it. The specified voltage is
determined by adding the peak value of the input signal and the
superimposed DC voltage: 300 V for the 300
µ
V ranges, and
500 V for the 3 V to 100 V ranges.
3.
Connection leads:
When the measured signal level is low (i.e. 300
µ
V) or the
measured signal source impedance is high, the input line is
susceptible to external noise. To resist the noise, shielded wires
or a coaxial cable should be used depending on the noise
frequency.
4.
Full scales:
GVT millivoltmeter adopts a special extended scale which has a
reading range larger than the conventional full scale.
Conventional
Extended
0 to 1.0
0 to 1.12
0 to 3.1 (3.2)
0 to 3.5
-20 to 0 dB
-20 to +1 dB
-20 to +2 dBm
-20 to +3.2 dBm
Note that the term “full scale” considers ‘1.0’ on the 0 - 1.12
scales as the rated value. The red
▼
mark is setting at ‘1.0’ on
the outermost scale.