new killer scope in town - a true game changer from R&S - RTB2002 & RTB2004

[nctnico]

Dear forum.
Sorry, I'm writing with google translate.
RTB2002 70Mhz base scope bad square signal representation in 200mV/div and higher positions.
100mV/div and lower is good, but not perfect either.
A square signal is definitely good, with several generators,
also examined with other scopes. I think it's a divisive problem in these jobs.
Running self alignment, it won't be good.

You have to adjust your probes. See the manual for the procedure.

[Fgrir]

Can they all be like this, or is it a unique error?

Mine's not quite as bad as yours, but it definitely has a similar issue at 200mV/div.  I am looking at the internal generator from the RTB2004, with 50ohm inline terminator.  The second image is the same signal viewed on my MSOX3024A.

EDIT:
Played around a bit more and all four channels on my RTB2004 behave similarly.  There is definitely a different settling waveform for 200mV/div and up vs. 100mv/div and below, and the relay click between those ranges says it's probably a different hardware path.

[goaty]

Gerade probiert, hier ist der Effekt nicht zu beobachten (rtb2004)

Ah wrong language mode, sorry.

I tried it out with BNC and 50Ohm inline terminator on all channels shortly after switching on, and I barely can see a
very slight bend at the rising edge of the 100Hz Signal (from internal Generator, but does not change on external Generator Siglent).

Nowhere near as bad as the pictures shown from other posters.

[capt bullshot]

Confirm that, it's even more obvious at 100Hz square wave signal (externall FG / 33120A and inline 50R terminator), but not as bad as the one from Miki6, rather similar to or maybe a bit better than Fgrir. So I'd guess it's a kind of design flaw, other scopes do a better job here. I've noticed fast edges aren't shown as nice as expected / possible. Otherwise, I bought that RTB2004 for it's vast capabilities and other "wow" stuff, but it's still somewhat disappointing discovering this particular issue.

Edit
Checked that with cycle RMS measurement and sine wave input: There's about 1% difference in amplitude from a below 1kHz to an above 1kHz input signal. Didn't check the specs of the RTB2004 whether this is within specs, but I wouldn't expect that behaviour from a decent oscilloscope front end.

[Miki6]

Probes set, same error with BNC - BNC cable. There should be no difference between 100mV/Div and 200mV/Div settings, even with a bad probe setting.

[Miles Teg]

Ha

Got my RTB2K-COM4 Full Package RTB ordered and paid 

But delivery expected end of december   

Need to find a solution for the 2 next months for hiFi repair and my GPS mower project.

[Hydron]

My RTB2k bought at launch shows very little difference on a square wave when changing from 100 to 200 mV/div. There is a tiny change but nothing even close to worrying.

[Miki6]

Looking at a 1KHz square wave signal? It is best seen there.

[EEVblog]

Dear forum.
Sorry, I'm writing with google translate.
RTB2002 70Mhz base scope bad square signal representation in 200mV/div and higher positions.
100mV/div and lower is good, but not perfect either.
A square signal is definitely good, with several generators,
also examined with other scopes. I think it's a divisive problem in these jobs.
Running self alignment, it won't be good.
Can they all be like this, or is it a unique error?
Thanks.

Confirmed.

[nctnico]

Interesting. It would mean there is something wrong with the LF compensation in the input. A frequency sweep should reveal a dip in the frequency respsonse. Probably somewhere between 500Hz and 100kHz.

[RBBVNL9]

It seems to me that the user interface is a – significant –  further development of that in the RTB2, RTM3 and RTA4 series, which I really like. And which allows the instrument to startup in mere seconds, talking of speed. (I might be wrong, though.).

For the record, it seems I was indeed wrong about expecting a fast startup time.. In his YouTube review, AddOhm mentions that ‘Reboot time is about 45 seconds’. That of the RTB Is 8-10 seconds, a feature a learned to love.

But otherwise, the MXO4 looks like a great step forwards in many dimensions..

[EEVblog]

Forgot I uploaded this!

[Hydron]

Went and checked all the channels on mine using the internal sig-gen, they don't look as bad as Dave's but there is definitely a change when the attenuator kicks in. In this case I grabbed a capture from each side of the range switch (~150mV, depends on the calibrated gain of each channel) using fine vertical gain adjust. Screenshot windows are due to me being impatient when capturing (they're confirming the previous screenshot).

I seem to recall this coming up for other scopes - was it Siglent that sent out repair kits to those brave enough to open their scopes up?

[Neurosurg]

Here are two undocumented SCPI commands that may be helpful.
Returns the times for the start and stop of the current acquisition. Also works in single mode.

Peter

Code: [Select]

:ACQuire:TIME:STARt?
:ACQuire:TIME:STOP?

e.g.
:ACQ:TIME:STAR?;STOP?
15,52,6;15,52,21


What I should do with this "Code"?
Can You explain? Give more info?
BTW Due to the new R&S Scope, I thought that it will be something similar to RTO6, but compare OLD RTO Family, something on lower level, medium like RTE1000/RTO1000, but in the new , for me not new small sister of RTO6. Just it.
Unfourtunetly out of reach for amators/beginners .. Eept to inflation, when I buy RTB2004-COM4, I just look on RTM3004-COM4, and price shocked me, I use it every day and has no problem. The scope is exellent.
Eept newgeneration I wanna hae RTE1204. I have compare and see that R&S, Keysight are made using TOP of the TOP materials.
Errors occures, I hope Rohde$Schwarz do something with it. But It doesnt see problem on my scope. Mayby a little.
Thanks,
Michael (Misza)

[goaty]

What I should do with this "Code"?

Those are SCPI commands for remote control of the instrument via network/serial/USB.

[Neurosurg]

Please explaiin me, csn somedbody say  is this error that can be just fied iif new correct firmware was realesed or iit is bad hardware problem. I am a little shocked.

[goaty]

Distortion is mostly visible with 1kHz square wave, so for most measurements -and the fact that one now knows the problem- it isn't a real problem at all.

It's a hardware problem, so Firmware won't fix it.

[Neurosurg]

Dave shows that it occurs in Riigol, Siglent, Tek Series 2.
So  They will have to make big repari action like is doing e.g. in the cars.
Should I give back my scope RTB204 because of that ?
I was etremly happy having him, I, donlt have money for RTM3000,but it probaly has the same issue.
Give me some tip, way what to do now.

[Neurosurg]

Distortion is mostly visible with 1kHz square wave, so for most measurements -and the fact that one now knows the problem- it isn't a real problem at all.

It's a hardware problem, so Firmware won't fix it.

Please give me advice what i should do. Give back to vendor the scope (has gwarantty 3 yers). I love this scope, but if it;s better to give back.
I do it, and wait collect money to buy RTE1000 on ebay, I had hope that next geneation will be reachable. But It is amazing but price is also amazing shoking.

[goaty]

I will keep it. It´s a good scope with great features.
As I know the limitation, I will not wonder whats going on once I measure 1kHz square in some future scenario.
99.9% of time one measures somthing totally different or amplitude does not play big role, but general waveform or frequency or...

[Neurosurg]

I will keep it. It´s a good scope with great features.
As I know the limitation, I will not wonder whats going on once I measure 1kHz square in some future scenario.
99.9% of time one measures somthing totally different or amplitude does not play big role, but general waveform or frequency or...

Thx, I suspect you are good in electronics, very good, having wide knowlage.
So if You keep It. I will keep it too. It is fantastic scope, design is great looks like high profesional scope, somebody do great job, thinked front panel.
I think too that it is very good oscilloscope, use It 3 months and everyday I;m impressed. Features and performance has exellent.
RTM3000 is 1/2 price of RTB2k-COM4 epensive, but iif i buy scope, i wanna have options, apps all with max BW.
RTM3000 with fully options is out of reach for me now
Funny, but siglent looks like has bigger screen then 10.1, but in datasheet is 10 inch. . R&S is big too, Siglent make case for this scope because  of looking like SDS6000 sister perhaps No my world Siglent, Rigol
Thx goaty
Siglent mayby has 12bit ADC, Rigol too, but, it isn;t so important. R&S I have in work. RTO2000 and I trust them,

[capt bullshot]

I will keep it. It´s a good scope with great features.
As I know the limitation, I will not wonder whats going on once I measure 1kHz square in some future scenario.
99.9% of time one measures somthing totally different or amplitude does not play big role, but general waveform or frequency or...

Looking at the step response of whatever kind of control loop, amplifier or whatever isn't that uncommon. You want an oscilloscope that doesn't add an unknown error here, I believe it's perfectly legal to expect a clean step response from any oscilloscope.

[goaty]

I got the RTB2k-COM4 for 2.5k€, which was great price. (Used but practically brand new).

About the step response: I´m bad at theory and math, so will that show up in any scenario ? I think I might do some tests to understand that better.

[Domitronic]

Interesting to see that the RTB seems to have a similiar issue as the Siglent SDS1104X-E. Wouldn't have expected this on the RTB in this price range and from R&S.

https://www.eevblog.com/forum/testgear/siglent-sds1204x-e-released-for-domestic-markets-in-china/msg4433131/#msg4433131

[capt bullshot]

I got the RTB2k-COM4 for 2.5k€, which was great price. (Used but practically brand new).

About the step response: I´m bad at theory and math, so will that show up in any scenario ? I think I might do some tests to understand that better.

There's some math behind the step response (just the first two search results):
https://en.wikipedia.org/wiki/Step_response
http://www.faadooengineers.com/online-study/post/eee/analog-electronics-circuits/1007/step-response-of-an-amplifier

In practice, looking at the step response of a circuit that you're developing, repairing or fine tuning reveals a lot of information about the circuit.
For example, the RTB2k shows a non-flat line at a 100Hz ... 1kHz square wave signal. One can translate this into the frequency domain (by math theory, FFT, or just some imagination from experience) - the non-flat line means the frequency response of the RTB2k isn't flat in that ballpark range. Now figure you're building a HiFi, or precision low frequency measurement amplifier or similar. Say you want a flat frequency response from DC to maybe 100kHz - one can use a frequency response analyzer to make a bode plot, or the old school analog engineer just looks at the step response to do a coarse judge of the amplifier while tuning its frequency response.
If the oscilloscope itself has an non-flat step response and you don't know about that, your amplifier will look bad, or if you know, how do you tell the amplifier and the scope response apart?
Even worse, if you use the built-in frequency response analyzer of that particular oscilloscope, it'll give you bad results, as the signal passes through the very same input that has the non-flat step response.

So, with this flaw, the RTB2k (and other scopes with a similar issue) disqualifies itself from precision analog measurements ...