Fluke 5700A Series, Руководство оператора

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18
Front Panel Keys (cont.)
C
Clears a partially completed keypad entry from the
Control Display, or clears an error message that
required acknowledgment, If there is a partially
completed entry when
C
is pressed, the output is
unaffected.
N
This key is only active during error mode
operation. It establishes the present output value
as a new reference for meter error computation.
D
When in the ac volts, or wideband function, and if
no entry is in progress, the
D
key shows the
equivalent dBm output on the Control Display. For
the ac voltage function, dBm is calculated for a
600
Ω
load. (For ac outputs less than 220 mV, the
Calibrator output impedance is always
50
Ω
because the output is resistively divided.
)
For
the wideband function, dBm is calculated for a
50
Ω
resistive termination at the end of a three-foot
50
Ω
coaxial cable.
Note
The formula to compute dBm is:
dBm = 10 log (power in mW)
Examples:
For 3.0V into a 600
Ω
load:
dBm = 10 log (15.000) = 11.7609 dBm
for 3.0V into a 50
Ω
load:
dBm = 10 log (180.000) = 22.5527 dBm