f) Attenuation measurement in dBm
The multimeter VC-12A enables absolute „dBì measurements in circuits
with an impedance of 600 Ohm. Measurements are made in the „V~“
range. 0dB = 1mW (0.775 V).
Proceed as follows to make the measurement:
- With the rotary switch, select the measuring
range „10 V
“.
- Connect the black measuring line to the
COM socket (5) and the red measuring line
to the socket „+“ (6).
- Now perform the zero adjustment.
- Now connect the two measuring probesto
the object to be measured (generator, switch
etc.).
- Read off the measured value on the scale
„dB“.
The dB scale corresponds to the 10 V-measuring range.
If another measuring range is selected, a correction factor must be taken
into consideration in the calculation.
AC-V range
10 V
50 V
100 V
250 V
Correction factor 0dB
+14dB
+20dB
+28dB
- If signals with a direct voltage ratio are to be measured, a capacitor of
>0.1nF must be connected in series to the measuring lines (decou-
pling).
- Disconnect the measured object from the mains and remove the meas-
uring tips from the measuring circuit after the measurement is complet-
ed. Switch off the multimeter (rotary switch position „OFF“).
G
~
44
