analoger wrote:Also any idea why oscilloscopes are super expensive?
An oscilloscope has to be faster and more accurate than the circuit you're trying to measure. If it isn't, you aren't getting information about the circuit under test.. you're getting information about the scope's limits.
You want at least five samples per cycle of the fastest signal you want to measure. If you want to measure circuits moving at 1GHz, you need to sample (accurately) at 5GHz.
analoger wrote:Like the one I want is Tektronix MDO4104-6, but it's overpriced I think.
Yeah, that's the kind you mortgage the house for.. but overpriced? No.
It has four analog channels and sixteen digital channels that can read signals moving at 1GHz (5GHz sampling rate), one RF channel that can measure signals up to 6GHz, a built-in spectrum analyzer, is capable of running all those at the same time and in sync with each other, and can read signals that rise from 0v to 1v in 350 picoseconds.
Now, when you get down to basic physics, electrical signals travel at about half the speed of light. At 5GHz, one wavefront is only about 3cm away from the next. Being able to resolve signals to 4mV per volt at that rate is no small trick.
analoger wrote:Rigol is cheaper but do they match the reliability and quality of Tektronix?
No, but that doesn't make them bad.
Tektronics and Aligent are the Rolls Royce and Ferrarri of instrumentation. It's not just that they make top-quality gear, it's that they have a track record of making top-quality gear that spans decades. Scopes like that come with a certificate that traces their calibration history to a recognized standards lab, and when you buy them you budget for a calibration cycle that will keep that paper trail going. The point of buying them is to have documentation that tracks their performance over their whole working lifespan, because that documentation is what allows you to trust the scope. In the worst case, you'd take that documentation to court to prove that your tests were reliable.
Rigol scopes are more like a Honda Civic.. good for everyday use, but you wouldn't want to bet your life on one. The 1052 series are good entry-level scopes. The 1052E is a dual-trace scope that sells for about $350, the 1052D has a 16-channel logic analyzer as well and sells for about $600. They're 'honest' scopes, in the sense that their sampling rate is higher than their rated bandwidth (1GHz sampling rate, 50MHz bandwidth). The ones that don't use what's called 'equivalent time sampling', which is garbage.
When you void a product warrany, you give up your right to sue the manufacturer if something goes wrong and accept full responsibility for whatever happens next. And then you truly own the product.