Performance Tests
Zero Test
HP EPM-441A/442A Service Guide 2-5
Zero Test
 Specification
Description
After the power meter is initially calibrated and zeroed, the change in the 
digital readout is monitored. This test also takes drift and noise into 
account, since drift, noise and zero readings cannot be separated.
Equipment
Range Calibrator .................................. HP 11683A 
Power Sensor Cable  ............................. HP 11730A
Test Setup
Figure 2-1:  Zero Test Setup
Electrical Characteristics Performance Limits
Accuracy: Zero set (Digital settability of zero)
±0.0764 µW
1
1. This performance limit is determined by the zero set specification of the power 
sensor used in the measurement plus the measurement noise. The range 
calibrator has a zero set specification of 
±0.05 µW. The calibrator measurement 
noise specification is 110 nW at 16 averages. At 512 averages a noise multiplier of 
0.24 is required, giving a measurement noise specification of 0.0264 µW 
(0.24x512).
HP 11730A
POWER
METER
CHANNEL A
Power Meter
Range
Calibrator
4402serv.book  Page 5  Monday, March 11, 2002  11:34 AM