AdvancedA-003-003-008
A dip meter:
A
Answer
Transmitters and receivers
Type
A
should be loosely coupled to the circuit under test
B
should be tightly coupled to the circuit under test
C
may be used only with series tuned circuits
D
accurately measures frequencies
Answer Notes
A dip meter (or grid-dip oscillator) is used to determine the resonant frequency of an antenna or tuned circuit. When using it, the meter's coil should be loosely coupled to the circuit under test—meaning it is held just close enough to observe a slight "dip" on the meter's indicator.
If the meter is tightly coupled, the physical proximity introduces stray capacitance and inductance into the circuit being tested. This loading effect will detune the circuit, resulting in a false or highly inaccurate frequency reading.
Dip meters are generally analog instruments that provide a good approximation rather than a highly accurate frequency measurement. Therefore, claiming it "accurately measures frequencies" is incorrect.
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