HP 34401A, User Manual

Page: 42 / 236

To Make dBm Measurements
The dBm operation calculates the power delivered to a resistance
referenced to 1 milliwatt.
dBm = 10
×
Log
10
( reading
2
/
reference resistance
/
1 mW )
•
Select
DC V
or
AC V
.
•
The factory setting for the reference resistance is 600
Ω
. To select a
different value, press
Shift >
(Menu Recall) after enabling dBm
operations. This takes you to the “
dBm REF R
” command in the
MATH MENU
( only if dBm is enabled ).
Go down to the “parameter” level, and then select a value: 50, 75,
93, 110, 124, 125, 135, 150, 250, 300, 500, 600 , 800, 900, 1000,
1200, or 8000 ohms.
•
The reference resistance is stored in non-volatile memory, and does not
change when power has been off or after a remote interface reset.
Enables dBm operation;
Press again to disable. Math annunciator is on when
dBm operation is enabled.
To read / edit the dBm reference resistance,
use the MATH menu.
2
Chapter 2 Front-Panel Menu Operation
To Make dBm Measurements
41