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Adjustments
Power Reference Oscillator Level Adjustment
HP EPM-441A/442A Service Guide
3-7
For this adjustment the following mathematical assumptions are made:
Equation 1:
can be manipulated to give 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%.
By substituting equation 3 into equation 1 and manipulating the result
you get:
This quadratic can be solved to give equation 2.
The definitions of the terms in equation 2 are:
•
V
0
is the voltage measured between V
comp
and V
RF
with no power
applied and after the HP 432A has been zeroed.
•
V
1
is the voltage measured between V
comp
and V
RF
with power
applied. This power is approximately 1 mW.
•
V
comp
is the voltage between the HP 432A V
comp
connector and
chassis ground with power applied.
•
R is the resistance of the mount resistor in the HP 432A power
meter.
•
Calibration Factor is the value of the thermistor mount at
50 MHz.
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
com p
V
1
V
0
–
(
)
«
V
0
V
comp
«
V
comp
4Volts
~
V
0
400
µ
V
<
0
V
1
V
0
–
(
)
2
2
–
V
comp
V
1
V
0
–
(
)
=
4 10
3
–
(
)
R CalibrationFactor
(
)
+
4402serv.book Page 7 Monday, March 11, 2002 11:34 AM
Summary of Contents for E4418A
Page 20: ...Contents 4 HP EPM 441A 442A Service Guide 4402serv book Page 4 Monday March 11 2002 11 34 AM ...
Page 22: ...Contents 6 HP EPM 441A 442A Service Guide 4402serv book Page 6 Monday March 11 2002 11 34 AM ...
Page 24: ...Contents 8 HP EPM 441A 442A Service Guide 4402serv book Page 8 Monday March 11 2002 11 34 AM ...
Page 25: ...1 Specifications 4402serv book Page 1 Monday March 11 2002 11 34 AM ...
Page 41: ...2 Performance Tests 4402serv book Page 1 Monday March 11 2002 11 34 AM ...
Page 59: ...3 Adjustments 4402serv book Page 1 Monday March 11 2002 11 34 AM ...
Page 71: ...4 Theory of Operation 4402serv book Page 1 Monday March 11 2002 11 34 AM ...
Page 85: ...5 Replaceable Parts 4402serv book Page 1 Monday March 11 2002 11 34 AM ...
Page 108: ...Index 4 HP EPM 441A 442A Service Guide 4402serv book Page 4 Monday March 11 2002 11 34 AM ...