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5.2 Voltage Attenuation Measure dB
When selecting the AC voltage function, a measurement
value can be measured as ratio in dBm with reference to a
reference level.
The display dBm refers to a reference impedance at a pow-
er of 1 mW, whereby it is possible to set various reference
impedance values.
The dBm display is calculated using the following formula:
dBm = 20 x log
10
[V
x
: V
Ref
]
Example:
The reference voltage V
Ref
= 0,7746V for a reference imped-
ance of 600
Ω
at 1m
Ω
. (U = P x R).
For a voltage measurement value of Vx = 9,8V the resulting
attenuation is:
20 x log
10
[9,8 V : 0,7746V] = 22,04 dB
Impedance values for selection:
4
Ω
, 8
Ω
, 16
Ω
, 32
Ω
, 50
Ω
, 75
Ω
, 93
Ω
, 110
Ω
, 125
Ω
,
135
Ω
, 150
Ω
, 200
Ω
, 250
Ω
, 300
Ω
, 500
Ω
, 600
Ω
, 800
Ω
, 900
Ω
, 1000
Ω
, 1200
Ω
"
Turn measurement function selection dial to V~.
"
Connect the test leads to sockets
and COM and
connect to UUT:
"
The measurement value is displayed on the screen.
"
Briefly press the SELECT key to change to the dB
measurement range.
50
Voltage Measurement