A staple of the radio amateur’s arsenal of test equipment in previous decades was the dip meter. This was a variable frequency oscillator whose coil would be placed near the circuit to be tested, and which would show an abrupt current dip on a moving coil meter when its frequency matched the resonant frequency of what it was testing. For some reason the extremely useful devices seem hard to come by in 2024, so [Rick’s Ham Shack] has come along with a guide to using a nanoVNA in their place.
It’s a simple enough technique, indeed it’s a basic part of using these instruments, with a large sensor coil connected to the output port and a frequency sweep set up on the VNA. The reactance graph then shows any resonant peaks it finds in the frequency range, something easily demonstrated in the video below the break by putting a 20 meter (14 MHz) trap in the coil and seeing an immediate clear peak.
For many readers this will not be news, but for those who’ve not used a VNA before it’s a quick and easy demo of an immediate use for these extremely versatile instruments. For those of us who received our callsigns long ago it’s nothing short of miraculous that a functional VNA can be picked up at such a reasonable price, and we’d go as far as to suggest that non radio amateurs might find one useful, too. Read our review, if you’re interested.
