Performance Tests
Zero Test
2-6 HP EPM-441A/442A Service Guide
Procedure
The following procedure should be performed for the Zero Test. 
Note   The procedure details the key presses required on the 
HP EPM-441A. For the HP EPM-442A the equivalent key presses 
should be performed on both channels.
1. Connect the equipment as shown in Figure 2-1. 
2. Switch the power meter on. 
3. Press  then  .
4. Press  ,   for a reading in watts.
5. Set the range calibrator as follows:
RANGE............................................ 3
µW
POLARITY ...................................... NORMAL
FUNCTION..................................... STANDBY
LINE................................................ ON
Note   When switching the range calibrator to STANDBY, allow enough 
time for the range calibrator to settle to its zero value before 
attempting to zero the power meter. This settling would appear on 
the power meter display as downward drift. When the drift has 
reached minimum, (typically less than 60 seconds), the range 
calibrator is settled.
6. On the power meter press  , 
,  
select 512 from the pop up window then press  .
7. On the power meter press  ,  . When the wait symbol 
disappears press  . Wait approximately 10 seconds for the 
wait symbol to disappear.
8. Wait 30 seconds then verify that the power meter’s reading is 
within 
±0.05 µW. Record the reading.
Table 2-2:  Zero Test Results
Min
Channel A 
Actual Result 
Channel B 
Actual Result 
(HP EPM-442A 
Only)
Max
-76.40 nW ________________ ________________ +76.40 nW
Preset
Local
Confirm
dBm/W
W
System
Inputs
Input Settings Filter
Enter
Zero
Cal
Cal 
Zero 
4402serv.book  Page 6  Monday, March 11, 2002  11:34 AM