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Power Reference Oscillator Level Adjustment
3-8 Agilent E4418B/E4419B Service Guide
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 Agilent 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 Agilent 432A V
comp
connector and
chassis ground with power applied.
• R is the resistance of the mount resistor in the Agilent 432A power
meter.
• Calibration Factor is the value of the thermistor mount at 50 MHz.
Equipment
• Test power meter: Agilent 432A.
• Thermistor Mount: Agilent 478A Option H75 or H76.
• Digital Voltmeter (DVM): Agilent 3458A.
Procedure
Note The procedure details the key presses required on the
Agilent E4418B. For the Agilent E4419B the equivalent key presses
should be performed on both channels.
1. Set up the DVM to measure resistance. Connect the DVM between the
V
RF
connector on the rear panel of the Agilent 432A and pin 1 on the
thermistor mount end of the sensor cable. Verify that no power is
applied to the Agilent 478A
2. Round off the DVM reading to two decimal places and record this value
as the internal bridge resistance (R) of the test power meter
(approximately 200 Ω).
•R (Internal Bridge Resistance)_______________Ω
0
V
1
V
0
–()
2
2– V
comp
V
1
V
0
–()=410
3–
()R CalibrationFactor()+