MM0474
LESSON 3.
POWER MEASUREMENTS EQUIPMENT PART II
AIPD Subcourse Number MM0474................. Power measurements
Lesson Objective ............................. After studying this lesson you
should be able to describe the
circuits
of
the
power
meter
calibrator and the principles of
power meter calibration.
You
should also be able to answer the
exercise questions without error.
Credit Hours ................................. Two
TEXT
1.
INTRODUCTION.
a. The model 8402B Calibrator (Figure 1) is designed to be used with the
entire series of 431 Power Meters.
The model 8402B performs three basic
functions: (1) verify full scale range calibration and meter tracking of the
power meters; (2) measure the operating resistance of the RF detection
thermistor elements used for power meter measurements; (3) provide a means to
make DC substitution power measurements from 1 microwatt to 10 milliwatts.
b. Specifications of Calibration Functions.
(1) Calibration points: output currents corresponding to the following
power levels for both 100 ohms and 200 ohms thermistor mount operation
resistance: 0.01, 0.03, 0.1, 0.3, 1.0, 3.0, 10.0, 8.0, 6.0, 4.0, and 2.0 mW.
(2) Output current uncertainty: 0.05%, 20 to 30C; 0.20%, 0 to 55C.
(3) Overall power meter calibration uncertainty: 2X current uncertainty
thermistor operating resistance uncertainty (0.16%, 20 to 30C, 0.46%, 0 to
55C).
(4) Thermistor operating resistance function, resistance center values:
100 and 200 ohms. Range: 0.5% about center values, adjustable in 0.1% steps.
Uncertainty: thermistor operating resistance can be determined within 0.06%.
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