New toy(?) scope Fnirsi DPOX180H, claimed 180MHz/500MSps (May 2023)

[Rooster Cogburn]

Having used the scope for a while, I have to say I quite like it. It's a great deal at ~99EUR shipped. I have some minor UI complaints like the lack of absolute position readouts for the cursors and a slow Auto function. The only major bug I've encountered is the finicky USB mass storage mode that doesn't work with any of my machine/OS combos and is officially Win10 only. The performance of the actual hardware platform is absolutely good enough for my need. Ergonomically, rubber membranes that are a little softer would be nice and I always think it would be nice if handheld scopes would include at least one encoder for adjustment. My wishes for further firmware updates or a successor device would really be to just fill out the rather spartan feature set compared to a typical Rigol/Siglent bench scope. Channel arithmetic, protocol decoders, more trigger options like video triggers, more measurements, etc. Mostly pure software stuff that could be added without changes to the underlying hardware platform.

[infino]

I also miss the accuracy of the DC voltage measurement, for example, instead of 3.0 volts the device shows 2.92 at 1 volt per cell.
Shows information about the second channel on the display when it is off, and vice versa.

Otherwise a very successful device for its money.
Fast interface, works fast, synchronizes the signal perfectly.

[Rooster Cogburn]

And since we're already complaining, this scope has a yellow and cyan color coded channel 1&2 but my probe kit didn't come with any yellow probe rings

I hope we can get another software update or two out of FNIRSI!

[infino]

I pointed this out on one of the forums, but I was misunderstood there ))))

[RAPo]

I just did buy one. Just for trying out.

There will also be a scopemeter from Zeeweii coming soon, but the price is not yet known.
https://www.eevblog.com/forum/testgear/another-dsodmm-zeeweii-dso3d12-claimed-120mhz250msps/

[Anatol_i]

I have a pair of DPOX180H. A big disappointment. Problems: cursor measurements, phantom line when viewing the meander fronts at a frequency of several kilohertz, in some cases hovering. You can still put up with this, because you can fix it with a new firmware if the developer releases it. And here's another problem: the compensation of the capacity of the probes is configured only in one of the operating modes. Compensation is performed when the input is open, when switching to a closed input, a distortion of the meander occurs. And vice versa. Tested on both devices. There is no such thing on ZEEWEII DSO2512G and other available oscilloscopes. It seems that this is a hardware problem, which consists in changing the input capacity of the device itself when changing the open/closed input. Sadly.

I will supplement it. I changed the probes to PP-150. The situation has not changed. Such a problem is at frequencies of one kilohertz and closer.
It turns out that every time you change an open input to a closed one and vice versa, it is necessary to compensate the probes. Does anyone else have this problem?

[leon255]

Does anyone else have this problem?

Confirm this.

[ptluis]

Does anyone else have this problem?

Confirm this.

dpox180h it's just a toy it fails on basic useful things. fnirsi rush on camouflage the squarewave thing to quiet the bad reviews that were messing with sales. They don't care about solving more important things like cursors. no feedback and no reply to emails. really bad.

[RAPo]

This is too harsh.
Fnirsi does reply to questions asked, gives feedback (even within a few workdays), and does make an update.
If you look at the .wav files you can see the square waves, no camouflage there.

The cursors implementation is indeed strange.

dpox180h it's just a toy it fails on basic useful things. fnirsi rush on camouflage the squarewave thing to quiet the bad reviews that were messing with sales. They don't care about solving more important things like cursors. no feedback and no reply to emails. really bad.

[infino]

no feedback and no reply to emails. really bad.

They always reply to me on Whatsapp

[Rooster Cogburn]

They were very friendly and responsive when I talked to them on Ali regarding the USB mass storage issue and the weird cursors. Don't know if we'll get improvements, but at least they listened and confirmed what I was seeing was working-as-designed for now.

At the risk of sounding like even more of a newb, could somebody explain this issue to me? After 5min of Googling I have still no idea what a 'meander front' is or what it means for an oscilloscope channel to be open or closed. I assume this is about the under/overshoot/ringing on fast edges, probe compensation and needing to readjust when a channel is turned on/off?

[RAPo]

Meander front is the trace you see on the oscilloscope when you apply a square wave signal.
That can be under/overshoot but I think in this context is the rise/fall down without a clear line on the DPOX screen.

[Aldo22]

Meander front is the trace you see on the oscilloscope when you apply a square wave signal.

Is the term commonly used in English?
I have no idea, but to me it seems more like a translation error from Ukrainian or Russian.

If you google for Меандр на осциллографе, pictures of square waves appear.

I would also be interested to know what is meant by "open or closed" here.

[Evi]

People,
how old are you?

[Aldo22]

People,
how old are you?

What do you mean?

[RAPo]

To meander is an English verb that means zigzagging.
But it is not a common electronics term.

I think open=DC coupling, closed=AC coupling of a channel.

Meander front is the trace you see on the oscilloscope when you apply a square wave signal.

Is the term commonly used in English?
I have no idea, but to me it seems more like a translation error from Ukrainian or Russian.

If you google for Меандр на осциллографе, pictures of square waves appear.

I would also be interested to know what is meant by "open or closed" here.

[Aldo22]

To meander is an English verb that means zigzagging.
But it is not a common term.

Thanks, but I think I was right about the translation error.
"Meander" in Russian simply means "square wave".
The automatic translation apparently does not take the context into account.

"Meander (...) is a periodic signal of rectangular shape, widely used in radio engineering and electronics."

I think open=DC coupling, closed=AC coupling of a channel.

Thank you! That sounds plausible.

[Rooster Cogburn]

Ok, makes sense now

And I can confirm that my meander fronts need to be readjusted when I open and close the channel. Sucks, guess that's a hardware issue.

[Bud]

I recall meander is a specific case of a square wave with 50% duty cycle. But i may be wrong, it's being long time since I left the university bench.

[tunk]

A new video showing that it goes to 180MHz (assuming there's no software cheats):
https://youtu.be/40kdorhPcqo

[leon255]

FNIRSI DPOX180H 1MHz-180MHz Frequency sweep: https://youtu.be/Hmsn_Jd4N5M

FNIRSI DPOX180H 1MHz-250MHz Frequency sweep: https://youtu.be/fTk_qah00Ak

[infino]

And here's another problem: the compensation of the capacity of the probes is configured only in one of the operating modes. Compensation is performed when the input is open, when switching to a closed input, a distortion of the meander occurs.

This problem exists for me as well.
And it is unlikely that it can be fixed programmatically.
Rigol 1054z does not have this problem.

[chronos42]

Hi,
I also can confirm the issue with the different compensation when switching between AC and DC. First I did not understand what Anatol_i  was talking about (lost in transition), but he is right. Seems to be a design flaw in the frontend, the input capacity is different some pF in AC and DC mode. Should not be like that, this can´t get fixed with firmware. Beside of this, I still like my DPOX, for a 100 € device it is good for what it is.

Update:
I was wrong, the input capacity only changes less than a half pF. It is more the coupling capacitor, which seems to have a too low value. At higher frequencies (e.g 10kHz) the problem vanishes.

[vk6zgo]

I recall meander is a specific case of a square wave with 50% duty cycle. But i may be wrong, it's being long time since I left the university bench.

If it doesn't have a 50% duty cycle, it is a rectangular wave, not a square wave.
No, I'm not splitting hairs, their frequency spectra are different.

[ru_tash]

.....It is more the coupling capacitor, which seems to have a too low value. At higher frequencies (e.g 10kHz) the problem vanishes.

I repeated tests, seems you are right, for 1kHz AC decoupling capacitor has too low value (flat part of square wave is declining and cannot be compensated), at 10kHz square wave has right shape (no matter AC or DC input).