Agilent Technologies E4418B - Page 75

Adjustments
Power Reference Oscillator Level Adjustment
Agilent E4418B/E4419B Service Guide 3-7
Note The power meter may be returned to the nearest Agilent Technologies
office to have the power reference oscillator checked and/or adjusted.
Figure 3-3: Adjustment Setup
For this adjustment the following mathematical assumptions are made:
Equation 1:
can be manipulated to give the following:
Equation 2:
by using the following assumptions:
The error in doing this is:
So if , that is, then the error can
be ignored. In practice and . The error is less
than 0.01%.
Power Meter
Agilent 432A
Power Meter
V
RF
Vcomp
Thermistor
Digital
Voltmeter
Power
ref
INPU
T
INPUT
+
Mount
P
meas
2V
comp
V
1
V
0
–()V
0
2
V
1
2
–+
4R CalibrationFactor()
-----------------------------------------------------------------------------------=
V
1
V
comp
V
0
V
comp
2
10()
3–
– 4R()CalibrationFactor()–+=
V
0
2
V
1
2
– V
1
V
0
–()–
2
=
V
1
2
V
0
2
2V
1
V
0
–+()
–
V
0
2
V
1
2
–()– 2V
0
2
– 2V
1
V
0
+2V
0
V
1
V
0
–()==
2V
0
V
1
V
0
–
()
2V
comp
V
1
V
0
–
()
«
V
0
V
com
p
«
V
comp
4Volts~
V
0
400
µ
V<
4402serv.book Page 7 Tuesday, October 14, 2003 3:18 PM