What does a dip meter do?

A dip meter is used primarily to give an indication of the resonant frequency of an unpowered tuned circuit, such as an antenna trap, a coil, or an LC circuit. When the dip meter's exposed coil is coupled to the circuit under test and tuned to its resonant frequency, the unpowered circuit absorbs RF energy from the meter. This causes a noticeable drop, or "dip," in the meter's feedback current reading. It is important to note that a dip meter only gives an approximation or indication of resonance. Because of its design and the loading effect of coupling it to a circuit, it is not highly precise and is not used to measure frequency, field strength, or power accurately.