That $20 RF probe I built from scratch beat my $400 oscilloscope for finding interference

I was working on this weird hum in a vintage receiver from the 70s last month, and my scope was showing noise but I couldn't pin down where it was coming from. One of the old guys on here mentioned building a simple RF probe with just a diode, a cap, and a resistor. I figured it was too simple to work, but I had the parts laying around so I soldered one up in about 20 minutes. Stuck it on my multimeter and started poking around the circuit board, and I found the bad solder joint on a filter cap within 5 minutes. The scope was telling me there was noise everywhere, but the probe helped me trace the exact path it was taking through the ground plane. Has anyone else had luck with these old school troubleshooting tricks that feel like cheating?

2 comments

2 Comments

xena_taylor645d ago

It is a good feeling when something that simple saves the day, and it is a shame that more people do not give these old tricks a try. I have been there myself with a piece of gear that was too smart for its own good, and a basic setup showed me the problem in no time. There is something satisfying about beating a fancy tool with a few parts from a junk drawer.

beth_hunt5d ago

Bet that scope was just showing you what you wanted to see instead of what was actually there. Modern gear makes people lazy about actually understanding what's happening on the board.