versatile, since they can operate at higher Q and lower amplitude, and are not tethered by a power cord. Dip meters of all types are being supplanted by antenna analyzers, which are more complex, but perform many of the same functions more conveniently, and require less dexterity. Operation The dip meter can be used either to measure the relative power lost to a nearby circuit (in which case the amplitude shown on the meter "dips") or to measure the relative power absorbed from a nearby powered circuit (in which case, the meter amplitude peaks). In either mode of operation, some experimentation is needed to find a distance between the pickup coil and the circuit under test, to ensure that the two circuits are close enough to transfer power, but not coupled so closely that the circuit supplied with power overwhelms the responding circuit, and forces it to oscillate regardless of the frequency. The art of coupling distance The heart of the instrument is a tunable LC circuit whose exposed external coil will loosely couple to the measured resonant circuit when held moderately close by. The measuring distance must be skillfully adjusted to be close enough to provide sufficient coupling for the dip to show clearly, but far enough that the meter and the tested circuit oscillate independently, so neither device's frequency is significantly distorted by the other, and so that power lost to the external circuit does not swamp the dip meter's oscillator. The coil and the test circuit can either be inductively or capacitively coupled: Coupling is inductive if the coil wires are held parallel to the nearest wires of the circuit being tested, capacitive if the coil wires and the circuit wires are held perpendicular. Depending on the context desired for the measurement, the circuit under test can be temporarily disconnected from its surroundings to avoid distortion by the parts it is normally attached to, or left wired in place to measure the response of the combined system. Emission frequency meter In ordinary use, only the oscillator in the dip meter is powered, and the circuit under test's only power is what it drains from the signal in the GDO coil. When both circuits are resonant at the same frequency, power transfer from the coil to the adjacent tested circuit reaches a maximum, consequently the dip meter's oscillator amplitude reaches a minimum due to the power lost to