AdvancedA-003-003-001
What is a dip meter?
D
Answer
Transmitters and receivers
Type
A
An SWR meter
B
A field-strength meter
C
A marker generator
D
A variable frequency oscillator with metered feedback current
Answer Notes
A dip meter, classically known as a grid-dip oscillator (GDO), is a testing tool used to find the resonant frequency of radio frequency circuits. It essentially consists of a variable frequency oscillator (VFO) and a meter that measures the oscillator's feedback current.
The device features an exposed coil that you bring close to the circuit you are testing. When you tune the VFO to the exact resonant frequency of the target circuit, the target circuit absorbs energy from the dip meter via magnetic coupling.
This sudden absorption of energy lowers the oscillator's feedback current. The operator sees this as a sharp "dip" on the analog meter, indicating that the resonant frequency has been matched.
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An oscilloscope measures 500 volts peak-to-peak across a 50 ohm dummy load connected to the transmitter output during unmodulated carrier conditions. What would an average-reading power meter indicate under the same transmitter conditions?
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What does a dip meter do?