Sometimes the old tricks are the best. [Kevin] learned an old trick about using a ‘scope to sniff RF noise and pays it forward by sharing it in a recent video. He uses an oscilloscope. But does he need some special probe setup? Nope. He quickly makes a little RF pickup probe, and if you have a ‘scope, we’re pretty sure you can make one in a few seconds, too.
Of course, you can get probes made for that, and there are advantages to using them. But the quick trick of quickly and non-destructively modifying the existing probe to pick up RF means you always have a way to make these measurements.
The first thing he probes is a small power supply that is broadcasting inadvertently at 60 kHz. The power supply was charging a bug zapper and, as you might expect, the bug zapper throws out a lot of noise on the radio bands.
If you have an FFT feature on your scope, that is often useful, too, as you can see the results of several interfering signals mixing together. Hunting down interference is a basic skill if you work with radio, and it’s useful even if you don’t.
In the early 1970’s, my computer repair toolkit included a small 6-transistor radio. Held near the backplane of the refrigerator sized computer, I could pinpoint bad cards as the machine was powered-on … different locations would “play” a different tune. One soon learned to identify the music of a correctly working machine.
Ah yes, the antenna ground lead. It works well for picking up noise, but makes a terrible ground when you’re actually trying to measure anything.