Reviving the Role of Dip Meters in Radio Hobbies
In the past, every radio amateur kept a dip meter within arm’s reach in their “shack.” However, with the affordability of oscilloscopes, the traditional dip meter has lost its significance and often vanished from the scene. It’s unfortunate because the dip meter can significantly simplify various tasks. For those who are intrigued, especially if revisiting the hobby, constructing a functional dip meter can be accomplished swiftly using this straightforward yet effective circuit. The essential question is: What functionalities does a dip meter actually need?
- A visual display of the dip? Nope, the ‘scope can handle that task.
- A large frequency scale? Not necessary, as you can connect a frequency counter for this.
- A selection of coils? We don’t need these because we can use a jumper to change range (no coils to lose anymore!).
Constructing the Sensor Coil for Frequency Range
The sensor coil, L1, comprises ten turns and is wound around an AA-size battery, serving as a former. This configuration allows for a frequency range spanning from 6 MHz to 30 MHz. When jumper JP1 is open, an additional fixed inductance of 10 µH is introduced into the circuit, altering the frequency measurement range to range from 2.5 MHz to 10 MHz. The switch can be replaced with a jumper for simplification.
Performing Frequency Measurements with Resonant Circuit
To take measurements, position a resonant circuit close to the sensor coil. Slowly adjust the rotary capacitor, C1, back and forth until the resonant frequency is found, marked by a decrease in the oscillator’s amplitude. The frequency can then be directly read from the oscilloscope. For precise measurements, a frequency counter can be connected to the second output, ensuring accuracy.
Versatile Applications of the Dip Meter
The dip meter serves a dual purpose: it can measure the relative power lost to a nearby circuit, indicated by a dip in the meter’s amplitude, or measure the relative power absorbed from a nearby powered circuit, shown by a peak in the meter’s amplitude. Essentially, the dip meter functions as a valuable tool for gauging power interactions between circuits, offering flexibility and applicability in various scenarios. Additionally, in geophysics, a dipmeter log is specifically designed to measure the dip and dip direction of surfaces in a borehole, providing essential data for geological analysis.