Keysight 85024A User's And Service Manual page 45

Calculating equivalent power
The probe is usually used as a high impedance device. The compression
specification is given as a voltage (instead of power) because of the wide range of
devices with which the probe may be used. For testing the probe, the probe
adapter is used to make the probe input 50 W. Using this known impedance, an
equivalent power can be calculated.
To find the power level equivalent to the 0.3 peak voltage, perform the following
mathematical steps:
Steps
1 Convert the peak voltage into
2 Convert the RMS voltage to a
3 Convert the raw power to a
4 Convert to dBm.
[a] Therefore, as shown in the example, the equivalent power to 0.3 V peak in a 50 W system is –0.458 dBm.
Keysight 85024A User's and Service Guide
RMS.?
raw power.
power which is relative to
1 mW.
Formula
V
pk
-------------------- -
1.4142135
2
V
--- -
R
Divide by 0.001w
10(LOGx)
Performance Tests
Example
0.3V
-------------------- - = 0.212132V
1.4142135
2
0.212132
( )
------------------------ - = 0.0009w
50W
0.009w
- - - - - - - - - - - - - - = 0.9
0.001w
10(LOG 0.9) = –0.458 dBm
5
RMS
[a]
45