The morale of this story is that you have two options:
1) pay, pay and pay for a "luxury scope" and almost believe in what you see - or
2) buy an affordable scope and be suspicious of everything you see.


And heaven, follow the well proven recommendations given by senior experts, like using double-sided PCB with solid ground plane, ADEQUATE power supply decoupling, use of shielded cables and Faraday cages, etc. etc. etc.

Only because you don't see the shit with a too slow scope, does NOT mean, that there is no shit!!!

Every engineer leaving university should have used at least one time a GHz scope and have had a look, what's going on in his 'low speed' circuit. He will be shocked, I can guarantee. And if he then refuses adequate RFI measures for his projects, he didn't understand anything.
If people see the first time this increadible big high frequency noise, they often say 'It's high frequency DIRT, it's irrelevant.' So, even when they see with own eyes what's going on, they still are so stupid not to learn and change their opinion. If you properly connect your high frequency probe of scope to your circuit, and you see high frequency noise, then it is there! Really! And you have something to do against it! Really!

And please, don't tell me something like 'Oh, it's too expensive to add two 100nF capacitors' or 'Oh, there's no place anymore on my PCB'. That's absolutely stupid. Think about the costs, when such a circuit refuses to work adequately in an industrial environment, think about the loss of reputation you will suffer. One lonely capacitor omitted in a certain application can influence your career...

Sometimes people are very simple minded. They use a high speed microcontroller and think they can succeed with a bread board design, adding only ONE power supply decoupling capacitor for 'cosmetic' purpose....

Kai