Operation - Kenwood VT-171 Instruction Manual

5. OPERATION

• Set-up
1. Press the O N / O F F p u s h s w i t c h © in, The Power-on
indicator ® , a light-emitting diode, w i l l light,
indicatting t h a t power has been applied.
2. Plug the measuring cable into the I N P U T connector
® .
3. Set the R A N G E selector® to " 3 0 0 V " T 1 0 0 V J .
T o measure an A C voltage superimpsed on a D C
voltage, be sure to set the R A N G E selector(3) before
connecting the cable to a point to be measured.
Otherwise, the D C voltage causes a high surge, which
could burn your V T - 1 7 1 T V T - 1 7 1 E J
4. Connect the cable to the point to be measure.
5. T u r n the R A N G E s e l e c t o r © until the Meter
swings over one t h i r d of the full scale.
6. Read the Meter.
(1) Voltage Scales
There are two black voltage scales : a scale @ graduated
0 to 10 and a scale ® 0 to 3. When the R A N G E selector
3 is a t " 1 V " , f o r example, the division 10 on the scale
®
® indicates 1 V . A t the "300 m V position, the division
3 on the scale © i n d i c a t e s 300mV. S i m i l a r l y , the other
R A N G E selector positions show their f u l l scale values.
(2) dB Scale
In general, the d B values are expressed in d B V which
is a unit referenced by 0 dB equal to 1 V . The division
10 a t the scale @ corresponds to 0 dB on the dB scale,
which is a voltage ratio scale. Since the R A N G E
selector has 12 range positions in steps of 10dB, the
voltage ratio of 1mV r o . 3 m V J to 300V r 100VJ is 110dB
attenuation.
scale @ be 1V w i t h the R A N G E selector a t " 1 V " a given
out.
voltage can be read as low as - 6 0 d B ( 1 m V ) l~-70dB(0.3mV)
by turning the selector downward.
pointer
@ a l l o w s reading to - 2 0 d B ( 0 . 1 m V ) [~-20dB(0.03m V ) J ,
you can continuosly measure the voltage r a t i o as high a s
- 8 0 d B ( 0 . 1 m V t o 1 V ) P - 9 0 d B ( 0 . 0 3 m V t o 1 V ) J . The read
of - 8 0 d B l~-90dBJ means a signal-to-noise ratio of
around 20dB F~10dBJ. Also,the dB scale a l l o w s continuous
measuring up to
by turning the selector upward.
Assume a reference voltage level on the
F u r t h e r , as the scale
+50dB(1 to 300V) l~+40dB(1 to 100V)J