Hi Tatel!
That screenshot (photo) was just meant to show the multiple lines phenomenon.
But it is the same as above: Coax, dummy load, TinySA sine wave at -7.0dBm.
Well, I want to summarize what we know so far:
1) This is a €100 device claiming it can do equally well or even better than a €500 device. My GW Instek couldn't do 120 MHz even after unlocked. So they have to be cheating on something, else Rigol, GW Instek and Siglent would be out of business right now. Nobody would be buying their devices if this Zeeweii thing can do about the same at a 20% the price.
2) What we want to know is what this device can actually do. I for one don't expect it to make that fanciful advertised capabilities good, but I want to know up to where it's really good. Only then anyone will be able to decide if it could really serve him well or not.
3) 4thDoctorWhoFan reported he measured 35 MHz bandwidth with just one channel activated IIRC. That means about 17,5 MHz with both channels, isn't that right? With overcloking, it goes to 40 MHz, again only one channel activated, so I guess it could do 20 MHz with both channels activated. This is with a 1Vpp signal, it isn't?
So it would be something like two DSO154 put side by side and overclocked to obtain a 20 MHz dual channel device. I wouldn't expect much more from a device in this price range. That would be good enough, I think, altought I would perhaps recommend the €125 Owon HDS242 instead (but no really sure about that: HDS242 seems to have caveats of his own).
Conclussion: if one wants a better oscilloscope than that, has to go higher in the price range. That's why Rigol, GW Instek and Siglent are still doing well, not closing their businesses. To expect more from devices in this price range (brand doesn't matter) would be just delusional.
4) If you remember, I said this would be the first time I heard about an oscilloscope whose bandwidth depends on input signal amplitude. I don't know how this can be, but I know if it can't do something at 1 Vpp, that's it.
Let's put marketing tricks aside. Capabilities of DSO2512 have to be compared with other devices capabilities on an apples-to-apples basis. I don't know how that multiple lines phenomenom is called, but I would call it "Zeeweii's cheating". To me it means it can't do even a sinewave at 70 MHz. So, it can't do 70 MHz, period. Matter is, can it do a 5 Vpp sinewave at 20 MH? At least DSO154 can do a 5 Vpp sinewave up to 18 MHz and a square one up to perhaps 2 MHz.
I beg your pardon for being so blunt. But we are chasing our own tails here. -7 dBm signals are useless unless same results can be achieved at > 1 Vpp. So enough of that.
5) Perhaps this thing can do not just 120 MHz, but 120 GHz when signal amplitude is lower than 1 Vpp, but even so, I don't have much use for that, so I don't care. I could recommend it to a newcomer by saying "you can expect this thing to be "good" up to 20 MHz with both channels activated, with the following three caveats: a) you'll need to put it in overclocking mode, b) in that mode, you'll have just one timebase (5 ns/div), c) you could do that exclusively with a sinewave.
Even that wouldn't sound so good as a recommendation for a device advertised to be able to do 120 MHz, don't think you so? So I'm not even to consider how could I recommend this device based in what it could perhaps do with signal amplitudes exclusively under 1 Vpp. That would be simply ludicrous.
6) So, to be able to asess what DSO2512 can actually do, what we need is a video showing how a known good 5 Vpp sinewave looks at different frecuencies. Coax+50 ohm. 1x attenuation. You can go up to 120 MHz or even further if you want. But I would bet 60 MHz will be enough to make things clear. Then please do the same with a 5 Vpp square wave. Then we all will we able to asess how good it really is and what it could be used for. Based neither in marketing advertisements nor prejudices, but on real data.
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