Recommendation? R&S RTA 4KCOM or Siglent SDS 5102X or Rygol MSO 8064

[Javaslinger]

Assuming prices are similar enough - which of these scope would you recommend?

[Noy]

Depends on what you need.
Tautech will jump in here in a few seconds for the Siglent one ;-)

I would take the Rigol and hack it. But for my needs 2GHz and Eye / Jitter measurments are more important than low noise like on the Siglent one or the 10bit from the R&S .

And the Rigol has single knobs for every channel...

[2N3055]

What Noy said...
What do you plan to do with it?
Also, prices won't be the same and different specs:

R&S® RTA4K-COM4  is full spec 1 GHz, 4ch+16Dch MSO with all extras included. All. And retail price of 12000€+ with tax in EU.

SDS 5102X is 2 ch 1 GHz scope. And seems to not be available anymore, probably because there was no interest in only 2 ch versions.
So your best bet from Siglent right now would be SDS5104X. But as Tautech said, if you buy SDS5054X now, for the price of 500MHz version you get 1Ghz version. For 6200 with tax in EU.

And MSO8064 that is 600 MHz scope... for 9000€ with tax.

[tautech]

Depends on what you need.
Tautech will jump in here in a few seconds for the Siglent one ;-)

I would take the Rigol and hack it. But for my needs 2GHz and Eye / Jitter measurments are more important than low noise like on the Siglent one or the 10bit from the R&S .

And the Rigol has single knobs for every channel...

And so does the SDS5000X series....but you are very correct about matching the right scope to the OP's needs.

It starts getting quite complex with midrange DSO's.....active probe support, options, mem depth, standard feature set and so on....
However SDS5000X are very recently on promotion so the price for a 1 GHz model is now the same for a 500 MHz model: https://int.siglent.com/info/detail-48.html

[Javaslinger]

Thank you all for your input.

Our situation is a little difficult as we are forced to buy a much more advanced scope than we need simply because we require high field.  We use them to diagnose NMR (Nuclear Magnetic Resonance) experiments and equipment.  In our case, we operate up to 600Mhz.  We do nothing fancy - simple observe the Rf pulse at various stages in the experiments and really require at most 2 channels.  So really, I'm not sure whether any of these would be better suited to what we're using it for.  Or perhaps the low noise and 10 bit might be the most helpful features.

I have worked with suppliers to be a very good price on the RTA4K-COM to put it in the ballpark of the other two.  There is apparently a pretty aggressive special running up to August.

To give some framework, we are replacing a Techtronix DPO4104 which was perfectly functional until it's demise.

So given that - I might think I should just buy the 'best' scope - Would that be the R&S?

Thanks again and Best!

[Noy]

The best scope is still the one which fits your needs most..

But if your Signal is going up to 600MHz and it's not a pure sine wave the 1Ghz from the R&S and the Siglent whould be to low / slow for your needs..

You should have 3-5 or more times more bandtwith than your measured signal if its not a sine wave..

[Jeroen3]

Beginning this year I made this comparison for the <500 Mhz variants. Eg: RTB2000, SDS2000 and MSO5000.
Chose the Rohde & Schwarz for the smooth UI and the biggest screen, also came with most options in a nice discount offer.

However, you also need to look at how the dac and memory is divided over the channels. Assuming you want to use more than one channel at once.
Your Keysight used to have 4 independent channels.

[bdunham7]

Assuming prices are similar enough - which of these scope would you recommend?

None of the above?  The R&S  will most likely be a high quality unit but I'd be reluctant to recommend them based on anecdotal evidence of craptastic support.  YMMV, especially if you are an institution, but I'd be wary.
The Siglent model you should be looking at is the SDS5104X so that you can have 5GSa/s on two channels simultaneously.  If it is available as a free upgrade or whatever from the SDS5054X, then all the better.  The Rigol is not a good choice unless you are going to 'enhance' it.  It is a 600MHz scope as delivered and that's not what you want for a 600MHz signal if you can easily do better.  As Noy said, you need a bandwidth well over the fundamental, especially if you are looking at the 'shape' of the signal as you stated in another thread.  However, you also said that you were using a 1GHz scope before you fried it, so if that has been working, I see no reason to spend extra for more bandwidth--but you certainly don't want less.

Forum decorum point--you have three threads on more or less the same topic.  EEVBlog threads often run for years and people do read them, so it is actually counterproductive in most cases to start new threads--and when you do so with good reason, you should link the previous thread(s).

[Rich@RohdeScopesUSA]

craptastic support. 

Craptastic support?  Ouch, that hurts.  Having worked for two major T&M suppliers for over 20 years, and knowing another quite well, I'd argue our support is on par with any of the major suppliers.  Sounds like you had a bad experience - don't hesitate to reach out to me if there is anything I can do to help.

@Javaslinger - feel free to reach out via PM (I don't always see threads - got lucky on this one) if there's anything I can do to help or questions I can answer on the RTA.

-Rich

[Sighound36]

Having own all three of these scopes for the low noise then the  Lecroy without question for the toys and not to shabby on noise in the mid and high range then then the Rigol hacks are plentiful for the 8000 and it stands up well i still use mine regularly, the Siglent is quieter at lower BW's. Much as I admire R&S as they do make some seriously quality kit there cheaper ranges of scope is not for me others will have differing views.

 
https://www.eevblog.com/forum/testgear/rigol-mso-8000/msg2883614/#msg2883614

[Rod]

Our situation is a little difficult as we are forced to buy a much more advanced scope than we need simply because we require high field.  We use them to diagnose NMR (Nuclear Magnetic Resonance) experiments and equipment.  In our case, we operate up to 600Mhz.  We do nothing fancy - simple observe the Rf pulse at various stages in the experiments and really require at most 2 channels...

No, you're not "forced to buy a much more advanced scope that we need."  Save your budget for new NMR probes , rather than blowing it on more 'scope than you need, or may ever use.

All that's needed to operate any NMR/MRI spectrometer (including those operating up to or above 1 GHz or with outputs up to or above 1 KW), tune its probes and amplifiers, and observe its transmitter and decoupler output pulse sequences, is:
- a couple diode RF detectors*,
- a high-power broadband 20+db (preferably dual) directional coupler*,
- a high-power 50 ohm 20+db attenuator or terminator*, 
- a few fixed 3 db, 10 db, 20 db 50 ohm fixed attenuators*,
- a double-balanced mixer (if you wish to examine phase modulation in sequences like TPPM),
- an assortment of coax cables,
- a couple 50 ohm terminators (if your scope doesn't have them built in)*, and
- a 50 MHz 2-channel 'scope (preferably with XY display capability) such as virtually any scope built by Tek, HP or RS for many years, or by Siglent, Rigol, etc.

*Narda-MITEQ, RF-Lambda, Bird, Pasternack, Minicircuits, HP/Keysight and a long list of others make these with your choice of Type N, BNC or SMA connectors.

All the above (and nice ones, at that) can be had used from resellers for a total cost <$500, or on ebay for <half that.

Most Bruker Avance and VNMR pulse programmers are limited to 100 ns time resolution.  Any scope with >10 MHz bandwidth can observe their pulse rise and fall times, lengths and delays.  (The Avance NEO now has 12.5 ns pulse steps, so a 100 MHz scope is needed to see its smallest steps.)  Onto the directional coupler or attenuator, simply plug a diode RF detector.  It converts RF pulses and into DC pulses, so any 'scope that that has rise/fall times faster than the pulses can be used to monitor their timing and amplitude.

Germanium diode detectors have now been supplanted by zero-bias Schottkey detectors, such as this one available at Digikey for $35.  https://www.digikey.com/en/products/detail/crystek-corporation/CPDETLS-4000/2685014

Only if you're an hardware geek who wants to build probes or hack, debug or service the electronics inside of the console, will you ever need, or even want, a scope that has enough bandwidth to see the observe and decoupling Larmor frequencies directly.  (Yeah, I was, so occasionally did.)  But while operating a half dozen supercon NMRs for years, I never once used more than 10 or 20 MHz of 'scope bandwidth, and only needed that much bandwidth when doing solid state NMR with sub-microsecond pulse lengths and delays, or 2D NMR with sub-microsecond pulse delay steps or lists.

The most useful suggestion I can offer is to pick up any used Narda 3020A directional couplers that come up cheap on ebay or at hamfests, and mount them permanently onto your transmitter outputs.  They are bidirectional 20 db couplers that are flat from 50 MHz to 1 GHz and can handle 500 W cw, 10 KW peak.  Then no student or technician in the lab will ever again accidentally blow out another 'scope!

[Rod]

Noy and bdunham7 make a good point:

But if your Signal is going up to 600MHz and it's not a pure sine wave the 1Ghz from the R&S and the Siglent whould be to low / slow for your needs..

You should have 3-5 or more times more bandtwith than your measured signal if its not a sine wave..

NMR spectrometers are simply fancy SDRs (software-defined radio transceivers) with specialized magnetic loop antennas ("NMR probes") stuck into expen$ive superconducting magnets.  They can transmit and receive on 3 or 4 independent channels (e.g. 600, 151, 92 and 61 MHz for H-1, C-13, H-2 and N-15) simultaneously.  Yes, they do transmit amplitude, frequency and phase modulation, but only over a relatively narrow bandwidth (<10 MHz), and they receive over an even narrower bandwidth (at most ~1 MHz, typically <100 kHz). 

For example, for "routine" solution 600 MHz H-1 NMR, the transmitted pulse sequence might span up to 10 MHz modulation bandwidth, but its antenna (NMR probe) has <2 MHz bandwidth (<1 MHz if it's a cryoprobe) and reflects anything outside of that, and the received NMR signals span only a 10 ppm = 6 kHz bandwidth, all at 600 MHz. 

To see all this, it isn't really necessary to have a 'scope with greater bandwidth than the NMR instrument itself can ever generate or receive, i.e. ~10 MHz.  So not to worry, but good point though! 

[jjoonathan]

Yes, but how many RPMs is the scope rated to spin at?

How many RPMs is the operator rated to spin at? 

[TurboTom]

In the lab, NMR doesn't necessarily have to be related to tomography, so spinning the equipment doesn't have to be involved.

[Rod]

Yes, but how many RPMs is the scope rated to spin at?

How many RPMs is the operator rated to spin at? 

   Problem is that the 'scope cables quickly get tangled up when it's spun at 600 MHz.  And the unfortunate operator isn't rated for those G forces!    The outcome might not be pretty... 

Otherwise, that's an excellent insight: if we did spin the entire NMR instrument at the Larmor frequency, then to do NMR we'd only need to apply and detect DC magnetic fields.  The nuclei wouldn't notice any difference. 

For engineering convenience, we choose to spin the magnetic fields (aka "the rotating frame of reference") rather than to spin the entire "laboratory frame of reference".  Magnetic fields don't have any inertia, so it's just a lot easier.

[RoGeorge]

Yes, but how many RPMs is the scope rated to spin at?

How many RPMs is the operator rated to spin at? 

   Problem is that the 'scope cables quickly get tangled up when it's spun at 600 MHz.  And the unfortunate operator isn't rated for those G forces!    The outcome might not be pretty... 

Otherwise, that's an excellent insight: if we did spin the entire NMR instrument at the Larmor frequency, then to do NMR we'd only need to apply and detect DC magnetic fields.  The nuclei wouldn't notice any difference. 

For engineering convenience, we choose to spin the magnetic fields (aka "the rotating frame of reference") rather than to spin the entire "laboratory frame of reference".  Magnetic fields don't have any inertia, so it's just a lot easier.

Not sure which NMR method is in discussion, but assuming we have a rotating battery to power the rotating instruments, will it still be possible to observe NMR?

Asking because the reference frame (in physics) usually does matter.  The reference frames doesn't matter and are interchangeable only when the two reference frames move at a constant speed.  When any speed variations are involved, then suddenly it does matter which one of the two frames of reference had the acceleration.  They suddenly become not interchangeable any more.

Rotation implies some change in speed/acceleration.  When something rotates or accelerates, the rest of the Universe suddenly does matter and the rest of the Universe does count like some sort of "ether" frame of reference.

For example, if there are two concentric circles, it does matter which circle is rotating.  The experimenter can not just rotate the other circle in the opposite direction and get the same effects.  Only the circle that rotates relative to the "ether" of the rest of the Universe will feel centripetal/centrifugal forces.

In my naive understanding I am picturing NMR as a wobbling spinning toy, and in NMR we observe/measure that wobbling (the precession), though there's nothing really rotating inside atoms and there is no axle in an atom, so will NMR be seen as DC if we rotate the detector?

If yes, what will happen with the DC if we change the orientation of the spinning axle of the rotating instrument?

[Rod]

Not sure which NMR method is in discussion, but assuming we have a rotating battery to power the rotating instruments, will it still be possible to observe NMR?

Yes (in any NMR method).

In my naive understanding I am picturing NMR as a wobbling spinning toy, and in NMR we observe/measure that wobbling (the precession), though there's nothing really rotating inside atoms and there is no axle in an atom, so will NMR be seen as DC if we rotate the detector?

Yes, that's the classical model of NMR precession.  The NMR signal is a rotating magnetic field, circularly polarized and rotating at the Larmor frequency.

In a stationary detection coil, we observe the NMR signal magnetic field induces a current, sine(Larmor frequency*time).  And if we place a second stationary detection coil perpendicular to it, in it we observe a current cosine(Larmor frequency*time).  (This is actually done by, for example, a "birdcage" coil, which has two physically orthogonal outputs.  By measuring whether the phase difference between them is +90 or -90 degrees, we can determine whether the NMR precession is occurring at a positive or negative frequency, thus directly determine the sign of the nuclear magnetogyric ratio.)

If the detection coil is rotating, the current induced in it will be the difference between the rotation rate of the detection coil and the rotation rate (Larmor frequency) of the magnetic field (NMR signal) it is detecting.  If rotating in opposite directions, this frequency will be higher.  If rotating in the same direction, this frequency will be lower.  If rotating at the same direction and rate, will be zero (DC). 

This is exactly how an AC generator (an alternator) works.  The rotor creates a rotating magnetic field, which induces a current in the stator windings.  If it has multiple sets of windings, we can tell which direction the rotor is spinning by the phase difference between the currents from the windings.  And if we were to begin to spin the stator in the same direction as the rotor, the frequency of the output current would fall.  If the stator were spun at the same rate as the rotor, the output frequency would be zero (DC).  So this is very simple.  The rest of the universe is unaffected.

If yes, what will happen with the DC if we change the orientation of the spinning axle of the rotating instrument?

Ouch!  Now my head is really spinning!       Hmm...

All the imaginary spinning we've done above is only of the detector, around the axis of the magnetic field produced by the NMR magnet, which defines the axis about which Larmor precession occurs.  Whether the magnet has rotated or not, its magnetic field has remained static; we have rotated around it.  So please clarify the question: by "rotating instrument", do you mean (1) rotating only the detector (NMR probe), or (2) rotating both the detector and the magnet (the entire instrument)?

If (1), then the detector, if still spinning at the Larmor frequency, will see two magnetic fields, both at the Larmor frequency and whose magnitude is proportional to the sine of the angle between the two axes: one enormous (produced by the magnet), and one tiny (the NMR signal). 

...and if you've ever pushed a conductor into a magnetic field of several Tesla, and felt it push back (due to the induced eddy currents), you can imagine what's about to happen...  a huge current will be induced, quickly heating the conductor... converting the energy of the entire magnetic field into thermal energy in the detector, which becomes a rapidly expanding ball of plasma.  Poof!  Ende gedankenexperiment!

If (2), then the result depends on how quickly we change the orientation of the magnetic field. 

If the change is slow compared to the Larmor frequency, the NMR magnetization simply follows it.  This is called an "adiabatic" process (termed "adiabatic" in that it does not change the spin temperature by inducing transitions between NMR spin states).

If the change is fast compared to the Larmor frequency, effectively instantaneous, the NMR magnetization does not move during this change, but suddenly sees the magnetic field appear in a new direction, and simply begins to precess about it.  This is termed a "nonadiabatic" process.

Both have been done in the laboratory (but by switching magnets on or off, not by rotating them).  It is called an "adiabatic demagnetization in the laboratory frame" experiment.  It has been described in many papers and several books.  A very clear description is given by Melton and Pollack, "Condition for adiabatic passage in the earth’s-field NMR technique", JMR 158 (2002), 15  https://ur.booksc.eu/book/4940715/42cb27
  In its Figure 2, the (a) nonadiabatic, (b) intermediate and (c,d) near-adiabatic cases are depicted.  This is simple classical magnetodynamics, more easily understood in a rotating frame of reference, although we detect it in the stationary laboratory frame of reference.

...and the analogous experiment can be done with rotating magnetic fields, "adiabatic de- or re-magnetization in the rotating frame"...  but that's enough for today!      

How did we get here from oscilloscopes, anyway? 

[RoGeorge]

How did we get here from oscilloscopes, anyway? 

Not sure how did we get here, but I'm very grateful for your answer, thank you!   

Read it twice, and if I understood correctly, it seems like a spinning-top toy with a bar magnet as its axle will be a very good macroscopic toy-model to interact with in order to grow an intuition about NMR.  Is this correct?

(I've made another topic to continue the talk about NMR:  https://www.eevblog.com/forum/projects/nmr-macroscopic-toy-model-to-interact-with/ )