Table of Contents
Advertisement
For this adjustment the following mathematical assumptions are made:
Equation 1:
(
2V
comp
P
=
---------------------------------------------------------------------------------- -
(
meas
4R CalibrationFactor
can be manipulated to give equation 2:
V
=
V
+
V
–
1
comp
0
by using the following assumptions:
2
2
(
V
V
=
V
V
–
–
–
0
1
1
The error in doing this is:
2
2
(
V
+
V
2V
V
–
–
1
0
1
(
) 2V
So if
2V
V
V
«
–
0
1
0
be ignored. In practice
than 0.01%.
By substituting equation 3 into equation 1 and manipulating the result
you get:
2
(
)
0
=
V
V
– V
2
–
1
0
comp
This quadratic can be solved to give equation 2.
The definitions of the terms in equation 2 are:
•
V
is the voltage measured between V
0
applied and after the HP 432A has been zeroed.
•
V
is the voltage measured between V
1
applied. This power is approximately 1 mW.
•
V
is the voltage between the HP 432A V
comp
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.
HP EPM-441A/442A Service Guide
Power Reference Oscillator Level Adjustment
2
2
)
V
V
+
V
V
–
–
1
0
0
1
)
3
–
2
(
)
(
V
10
4R
–
comp
2
)
0
2
2
)
(
)
V
V
=
–
–
–
0
0
1
(
)
, that is,
V
V
–
comp
1
0
and
V
~
4Volts
comp
(
)
(
V
V
+
4 10
–
1
0
) CalibrationFactor
(
2
2V
+
2V
V
=
2V
0
1
0
then the error can
V
«
V
0
comp
. The error is less
V
<
400µV
0
3
–
) R CalibrationFactor
(
and V
with no power
comp
RF
and V
with power
comp
RF
connector and
comp
Adjustments
)
(
)
V
V
–
0
1
0
)
3-7
- Quick Links:
- Power Meter Specifications
Hide quick links:
Advertisement
Table of Contents
