On the Elecraft mailing list, there’s been a flurry of messages recently about LCR meters. One of the units touted was a unit from a company called Almost All Digital Electronics. They have both a kit version ($100) and an assembled version ($130). A couple of the guys even bought and built it.
I chimed in with the opinion that instead of buying yet another meter, that they should just buy an antenna analyzer to make those measurements. My analyzer can measure inductance and capacitance directly, and do so at any frequency up to 35 MHz. It may not be quite as accurate as the LCR meter, but my guess is that it’s plenty accurate for amateur use. And to top it off, I get to use it to analyze my antennas!
One of the non-conventional ways that I use the antenna analyzer is to demonstate the principles of reactance and impedance to my General class students. First, I measure the reactance of a coil that I’ve had around the shack for ages (at one time, I used it as a loading coil coil for a vertical antenna). I show how the reactance increases with frequency, then record the reactance at 6 MHz.
Next, I measure the resistance of a 150-ohm precision resistor that came with my analyzer. Then, I calculate the impedance with the equation Z = sqrt(XL**2 + R**2).
I then connect the resistor in series with the coil and measured the impedance. Surprisingly (or, not so surprising, actually) the measured impedance is almost exactly what I calculate.
Actually, my analzyer–the Autek VA1–is not an antenna analyzer at all. It’s called a vector analyzer. Most of the high-end antenna analyzers can make these kinds of measurements. They can also be used as low-level RF signal generators. So, while they’re most useful at analyzing antenna parameters, they can be used for more than just that.
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