R&S NGE100 voltage jumping around - Page 1
Forum section: electronics / testgear

author: justanothername
author_rank: Regular Contributor
timestamp: October 06, 2020, 12:15:01 pm
content: Hi.I have here a brand new R&S NGE100 from work. My colleague gave it to me to verify. He said that the voltage is slowly jumping around..I can confirm this, look at the chart I recorded. Anyboy knows whats going on here? Should I send it back?

author: Alex P
author_rank: Contributor
timestamp: October 06, 2020, 04:19:37 pm
content: Is it set to supply 4V? And what is the current? You don't have EasyArb or EasyRamp enabled?

author: justanothername
author_rank: Regular Contributor
timestamp: October 06, 2020, 04:22:55 pm
content: Supply is set to 4V. No current (directly into the multimeter). No arb or anything.

author: Cloud
author_rank: Regular Contributor
timestamp: October 07, 2020, 09:36:44 am
content: What if you try to load it up a bit and measure then?

author: justanothername
author_rank: Regular Contributor
timestamp: October 07, 2020, 03:06:08 pm
content: Ok I connected a 390R ceramic resistor to the channel and the jumpy behavior seems to go away.But look at the charts! It is a really terrible noisy and drifty power supply!with 11mA@4V it has a range of 38.7mV!! This PSU has a price of over 1000€!The jumpy drifting on light loads is also unaceptable if you ask me!What should I do? Do you think this device is faulty?

author: maginnovision
author_rank: Super Contributor
timestamp: October 07, 2020, 05:35:56 pm
content: You're certain it's the PS and not the meter? If you've had same results with another meter and compared your measured stability with the spec in the datasheet and it's outside of that tolerance... Then something is wrong.

author: ogden
author_rank: Super Contributor
timestamp: October 07, 2020, 06:02:11 pm
content: Quote from: justanothername on October 07, 2020, 03:06:08 pmIt is faulty when does not meet thespecs:Voltage noise specification:typ. < 1.5 mV (RMS)< 20 mV (peak-to-peak) (meas.)There's catch: noise specified for frequency range 20Hz-20MHz. If during 0.05s voltage change does not exceed 20mV, then everything is fine with your supply

author: YetAnotherTechie
author_rank: Regular Contributor
timestamp: October 07, 2020, 11:26:39 pm
content: I used a 100ohm resistor and got the data in the picture.I tried to match your scales as close as possible, BW is limited to 20Mhz, the blue line is a low pass filter of 100Hz.According to this, mine is within spec, is it reasonable? i don't know, I've read here in the forum that HP's are much quieter.

author: RBBVNL9
author_rank: Frequent Contributor
timestamp: October 08, 2020, 04:21:46 pm
content: QuoteInteresting! But your post does not say much about the measurement setup. How confident are you that the noise and spikes you see are actually coming from the NGE?In a recent threathttps://www.eevblog.com/forum/testgear/seeking-psu-advice-rohde-schwarz-nge103b-com3-or-keysight-e36313a/msg3227650/#msg3227650, several people discussed the the NGE series, several of its shortcomings, and also shared ripple and noise measurements. Looking at these, receiving input of others, and measuring several PSU’s myself, i learned how critical the measurement setup is. A regular scope probe with a 4cm ground lead, for instance, can already result in picking up a lot of induced signals, and do what you then see may not come from the PSU but from elsewhere (like dimmer circuits closeby). Using just two banana cable leads from PSU to meter (instead of coaxial cable) will even make things much worse.See also the below video of Dave, where he advises a differential probe setup for PSU ripple and noise measurements.QuoteThe NGE series are certainly not having the lowest ripple and noise specs around. Many power supplies in this price range (and also cheaper ones) have considerably better specs. But measuring whether a NGE is within its specs is not a trivial matter…

author: justanothername
author_rank: Regular Contributor
timestamp: October 09, 2020, 02:54:23 pm
content: I've redone this test with a test setup as proper as possible (see attached pictures).I've verified the performance of my multimeter before testing with the PDVS2mini voltage source. As you can see, the multimeter works fine. All units had more than 30 minutes to warm upI've made recordings for over 10 minutes with and without a light load of 390 Ohm. It is still very bad, having a voltage range over 30mV.I can do tests with an oscilloscope, I got a Picoscope4000 for noise measurement. But I think this alone proves that the unit is defective or what do you think?Edit: I hooked it up to the picoscope4000.It shows >70mV peak-peak noise. With an USB isolator (necessary!) i could measure the noise. Yes, within a window of 50ms, it is less than 20mV noise. But it looks not good in longer time frames. Note that the measurement is ac-coupled, so voltage changes would look like spikes.In comparison, the PDVS2mini in battery mode shows 1.6mV p-p noise.Edit2: attached some faster readings with the sourcemeter as 100mA load. ~ 29mV range.

author: maginnovision
author_rank: Super Contributor
timestamp: October 09, 2020, 04:02:24 pm
content: Smu shows it's in spec, right?

author: justanothername
author_rank: Regular Contributor
timestamp: October 09, 2020, 04:11:24 pm
content: Quote from: maginnovision on October 09, 2020, 04:02:24 pmIn my opinion not. It has a peak-to-peak-range of ~29mV. A problem is that this is not defined in the data sheet since the noise measurement is from 20Hz upwards.I'm still waiting for a reaction of our local representative.But if they tell me it is in spec and I should f*ck off, then people beware of this PSU!Edit: Lets wait what they say.

author: maginnovision
author_rank: Super Contributor
timestamp: October 09, 2020, 04:34:07 pm
content: Well that's fine but 1 unit is not representative of the product in it's entirety. It's possible that your unit is faulty. I'd rather see more examples before condemning it. It's entirely possible that it's not suitable for low noise or that unit isn't performing well.

author: RBBVNL9
author_rank: Frequent Contributor
timestamp: October 09, 2020, 05:11:41 pm
content: QuoteI find that hard to say. Let us remind us again what the R&S specs are:Voltage ripple and noise (20 Hz to 20 MHz):- typ. < 1.5 mV (RMS)- < 20 mV (peak-to-peak) (meas.)Firstly, like noted before, good noise and ripple measurements are difficult to make. Potential issues are:Induced signals resulting in common mode noise (the reason some are suggesting differential probes to address this)Mismatching loads resulting in reflections and ringing; note the PSU output impedance is in the mOhm range (milli), and that of the scope is typically 1 MOhms (Mega) (there are impedance matching solutions to address this)Ensuring measurements are under different voltage and load conditions that those used for the specifications (unfortunately often not provided by the manufacturer),Impact of temperaturePossible impact of other devices used in the measurement chain. For instance, an electronic load may be cause of problems (but may be the only practical way to measure a PSU a specific series of voltages and loads). Or, if a wire-wound resistor is used as load, its parasitic inductance may have an effectYour new measurement setup is probably better than your first one, bt may not address all above issues.Having that said, lets now look at your Picoscope screenshots. I do not know that instrument well, but the screenshots you shared seem to show only peak-to-peak measurements, not RMS measurements. That limits us in answering your question. I also cannot see whether the bandwidth of the measurement was limited to 20MHz (which is the way the specs are specified). Especially because there are switching elements in this PSU, this bandwidth may really make a difference. The peak to peak measurements on your screenshot seem to be close to the specs, though.Yesterday, I did some more ripple and noise measurements on my NGE103B (and acknowledging these are probably far from perfect for reasons mentioned above). My results are roughly speaking in line with thoseposted by Fixpointa short while ago, and thoseposted by YetAnotherTechiein this threat. Depending on the voltage and load, my measurements are close to the manufacturer’s specifications: not much better, not much worse either.Despite the possible imperfections, let me share my measurements:First measurement uses a 19Ohm resistor as a load, PSU set at 10V, and a resulting 0.54A current flowing. I do this to be able to see whether the electronic load, used for the following measurements, makes a lot of difference. PP and RMS results are close to R&S specifications. (See pictures Ripple 1 and Ripple 4)The second measurement is basically the same, but now the 19Ohm load is an electronic load. The waveform is not identical (may have several reasons) but the resulting PP and RMS results are again close to R&S specifications. Using an electronic load instead of a resistor does not seem to affect findings a lot (see picture Ripple 2). (Note that Dave, in a video above in the threat, finds that the electronic load is a source of measurement problems in a similar setting.)Thirdly a measurement at full load (10V, 3A, which is the maximum for that voltage because of the 33W per channel). Now we go above R&S specifications by a factor of 2-3, but again, I cannot be confident the measurement is perfect so cannot claim lack of compliance. (see picture Ripple 3)QuoteYes, I see that is lower than the noise you measure yourself from your NGE. But it may not be a fair comparison. The NGE is a power supply, designed to significant current over a wide range of voltages. To do so in a compact housing R&S chose to use a switching regulator (offering efficiency and compactness) followed by a linear control circuitry (for stabilisation). Having switching elements inside (like many modern designs do) inevitably will result in some noise on the outputs. Comparing that to a device solely design to be a close-to-perfect voltage source may not be fair.IMHO, the bottom line is that the NGE100 series may not be one's first choice when shopping for a low ripple PSU, its specs in this regards are certainly not stellar. But whether a specific unit meets those specs is not that easy to measure, and the measurements of NGEs we have seen up to now seem to suggest they are close to or meeting the specs, despite probably measurement imperfections.

author: justanothername
author_rank: Regular Contributor
timestamp: October 09, 2020, 05:15:07 pm
content: @RBBVNL9 I have problems in a complete different time base than you. In my case it is drifting, over tens of seconds or minutes! My logging setup with the HP 34401A is one measurement per second.

author: ogden
author_rank: Super Contributor
timestamp: October 09, 2020, 05:18:03 pm
content: Quote from: justanothername on October 09, 2020, 05:15:07 pmExacty. You are trying to prove that your supply does not meet specs ofunspecifiedlong term drift

author: justanothername
author_rank: Regular Contributor
timestamp: October 09, 2020, 05:21:30 pm
content: Yes that is why I need the help of the community to have a measurement to compare to. I need anything to put this back to R&S since yes, I made the decision to upgrade to this PSU und I myself have to fix this problem, my coworkers threw this unit back to me. At the moment nobody wants to work with this and its B2B, so no returns.But I'm sure that this is not a normal behavior for a power supply that expensive.

author: RBBVNL9
author_rank: Frequent Contributor
timestamp: October 09, 2020, 06:47:05 pm
content: QuoteOK. Maybe I did not realise this well enough as you talked about noise (with I associate with short time spans) and this threat is talking about meeting the published specs (and the only specs in this respect are those on ripple and noise and given for 20Hz and higher only).If the issue is longer term voltage drifting, then I really would be fascinated to see whether this is somehow related to the design of having a switching regulator first and a a linear control circuitry next. I don't know the details of the NGE design, but I wonder whether it involves some steps in the process, and these could possibly explain the behaviour you seem to notice. If so, then such issues may occur at certain (threshold) voltages and not at others. This all is pure speculation, however.QuoteI guess that if we are to measure multi-second voltage drifts, AC coupling is not the way to go (especially if we don't have precise information on the ac decoupling characteristics of our measurement device). Rather DC measurements, and perhaps also ensuring that unwanted higher frequency AC components are filtered out effectively. Perhaps even charging a relatively large capacitor when longer time spans are of interest.If you know what you're exactly looking for, I'd be willing to make the same measurement here using the same set-up and share with you what I get.

author: justanothername
author_rank: Regular Contributor
timestamp: October 09, 2020, 06:53:35 pm
content: Quote from: RBBVNL9 on October 09, 2020, 06:47:05 pmThank you for that offer. I guess it would just help if you connect a 5.5 digid DMM or better to the PSU and measure the voltage with 1 reading per second over a span of 2 minutes or longer.Without load and optionally with 1mA and 100mA load. I have this behavior at all voltage ranges, but in this case the measurements are all done at 4V. I can repeat the measurements with any voltage if necessary.

author: ogden
author_rank: Super Contributor
timestamp: October 09, 2020, 07:45:58 pm
content: Quote from: justanothername on October 09, 2020, 05:21:30 pmNah. In this price range you get similar specs (20mVpp) from Keysight as well. Even worse - just 1 channel and much lower current capacity supply (E36104B). If you wantlowlower noise, then look for something like E36313A or NGL202. Also read the funny datasheets

author: RBBVNL9
author_rank: Frequent Contributor
timestamp: October 10, 2020, 02:03:34 pm
content: @justanothernameI now did the measurements you asked for. They are done with the NGE103B set to 4V output and the following conditions:- No load- 1mA load (using a 3.9 kΩ resistor as load)- 100mA load (using three 120 Ω resistors in parallel as load)Measurements are done with a Siglent SDM3045X DMM. That is only a 4.5 digit DMM, but given the voltage differences we are interested in, it seems fit for this task. I also repeated the measurements with a set of 3 new AA battery as voltage source, to check there is no short-term drift in the DMM itself, or inaccuracy in repeated measurements (there is not).This DMM also has an AC filter. According the manufacturer: “The analog filter of the Multimeter can be used to reduce the influence of the AC component in DC measurement. Generally the filter may not be required, but sometimes it can improve the DC measurement. For example, if the measured DC electrical source has a big AC ripple, the analog filter can reduce the influence.”Every measurement I did consists of 120 samples, with an in-between delay set to 1.0 second. Because the measurement itself also takes some time, the total time span is a bit longer than 2 minutes (2 min 26 seconds to be precise).The data file is attached at the end of this post, as well as some graphs.My observations are:- The AC filter does not seem to affect measurements a lot, but it does seem to need some time to stabilize. So for PP calculations, I’ll ignore the first 20 samples (where this stabilisation takes place).- Overall, in all my measurements (of 2.5 minutes each), the maximum PP difference is 20 mV or lower.- In two cases, I do observe a voltage step (see the red arrows in the graphs), both of about 10mV. Both times this happens during measurements with the AC filter on, but I take that as coincidence (N is way too low to make any inferences).As discussed above, R&S only has published specs for ripple and noise for 20Hz to 20MHz, and not for slower voltage drifts. During the measurements I did (which are not infinitive or exhaustive), the average drift over 2.5 minute periods was 12mV, and the maximum drift I saw was 20mV. I guess this is good enough for my purposes, but others may have other needs.Yet, the steps I observe are fascinating, and they would be compatible with the idea of the design (a switching regulator followed by a linear control circuitry) indeed has discrete steps when doing its work. But of course this is speculation, not evidence.

author: rf-messkopf
author_rank: Regular Contributor
timestamp: October 10, 2020, 03:15:43 pm
content: Quote from: RBBVNL9 on October 09, 2020, 06:47:05 pmI don't know whether this is of interest in the present thread, but by coincidence I noticed a similar jumping of the output voltage on an Agilent E3646A. See the attached picture: The output is set to 5V and directly connected to the multimeter (no load). It does jumps of about 500µV. When I noticed that I just shrugged my shoulders as it is within spec (<0.01% of output voltage + 3mV), even though it's not exactly nice.The Agilent E3646A has no switching regulator, and the jumps are present on both channels. I haven't seen any jumps on a R&S HMP4040 that is sitting next to it, which does have a switching pre-regulator, but is somewhat more noisy than the Agilent.

author: justanothername
author_rank: Regular Contributor
timestamp: October 10, 2020, 05:52:51 pm
content: Thank you for the measurements RBBNVL9!Your measurements seem to be way better than mine!You have 7.7mV at no load min to max, the worst value is 11mV at 100mA. This is the performance I'm expecting.My NGE has around 30mV at all loads to 100mA, so it is definitively worse! I will return the device and lets see what happens.

author: Fixpoint
author_rank: Regular Contributor
timestamp: October 13, 2020, 08:49:56 am
content: I am skeptical that all this is really meaningful.(a) Firstly, keep in mind that your measurements are not necessarily comparable with each other because you don't have the same conditions. For example, the performance of your power supply is influenced by your mains characteristics. If somewhere in your house a fridge, a vacuum cleaner, or an LED lamp turns on, this could change the behavior of the power supply. Some of you may have a very clean mains, others a very noisy or "ripply" one. If one of you measures "30 mV" and another "10 mV", what does that mean? I don't think that it means much as long as we don't know all the parameters. In my opinion, performance measurements must be done under very well-controlled conditions, otherwise they are of very limited value because we don't really know how to interpret them. We can only use them as ballpark indicators.(b) Secondly, keep in mind that we don't buy equipment "just because" (except we are collectors) but for using it for something. I am using the NGE103B on a daily basis for hours (and yes, I am doing precision stuff with VCOs), it does its job very well, and I never think about 10 mV or 20 mV ripple just because I have better things to do. So, is all this talk really worth the time? Just build something ...

author: justanothername
author_rank: Regular Contributor
timestamp: October 13, 2020, 09:17:11 am
content: Fixpoint, we bought this PSU as replacement for the old analog Hameg 3ch PSUs. As such it was presented to us by R&S when we visited them. Whatever my coworker was trying to do, he searched for an error in his circuit awhile before pinning it down to the new PSU and throwing it back to me. Hes is using the old one again.And I don't know why a properly built PSU should jump 30mV around at 4Vconstantly, even when mains is unstable (which is not, of course). I just needed to know if others have the same flaws, seems not, so I will send it back!I would overlook this when it would be a cheap aliexpress PSU but not for a >1000€ unit.

author: Fixpoint
author_rank: Regular Contributor
timestamp: October 13, 2020, 10:16:27 am
content: Quote from: justanothername on October 13, 2020, 09:17:11 amHonestly, I have to wonder what you and your coworkers are doing.(a) It sounds that you are doing precision stuff but are using a device that is officially not meant for precision stuff (just have a look at the specs). R&S marketing material clearly states that the device is primarily aimed at the educational sector, i. e. schools and universities, and that ROBUSTNESS is its primary feature, NOT accuracy (they say that it will "survive generations of students").(b) You are complaining that the device does not satisfy an *unspecified* specification, and god knows what your conditions of your measurements were. R&S "only" talks about a specific frequency range? Yes, because that's the industry standard for PSU specs ... I think that's ok.I would never argue with "a 1000 EUR device must do this or that, even if unspecified". Well ... that may be your opinion, but it will only buy you frustration. The price has nothing to do with anything. If you have SPECIFIC requirements, you must look for EXACTLY the right equipment and ask for the numbers. Yes, the price is a number, but ... the wrong one.BTW, just for the sake of completeness, I also made a few measurements some weeks ago. Just ballpark, of course.https://www.eevblog.com/forum/testgear/seeking-psu-advice-rohde-schwarz-nge103b-com3-or-keysight-e36313a/msg3231192/#msg3231192

author: RBBVNL9
author_rank: Frequent Contributor
timestamp: October 13, 2020, 01:05:18 pm
content: The previous email stresses we should look carefully at what the manufacturers actually specify, claim or say. A few comments on that in the context of this NGE PSU...QuoteTo know what 'it' means in the above sentence, we need to look at the R&S brochure. That says"The design of the connectors is robust enough to survive generations of students."So this statement is specifically about the output (banana) connectors of the device. I hope this high robustness level also holds for all other parts, but that is not what they claim.Just talking "specified" and "unspecified" ;-)QuoteThis may be your interpretation, but I do not see that written in the market material - at least not the R&S data sheet / brochure for this device (from which you seem to have taken the above statement). There it says"Tailored to be used in education, labs and system racks". (They use this sentence 3 times). So I see three applications listed, including 'labs'. And to be sure, that same word 'labs' is used in the marketing material for the more expensive R&S series like the HMP, HM, NGP and NGP series.QuoteFinally, I agree that if specifications are provided, then we should look at them (and judge on them). Still, I feel a bit uncomfortable that no later than thesecondsentence in the NGE product procure reads"They offer high efficiency combined with low ripple [...].". That may be a bit misleading for an PSU who's ripple specification (and actual performance) seems considerably below (meaning 'worse than') that of comparable devices.(I admit we can have a discussion on what 'comparable' means. With N=1 let me just mention the Keysight E36300 Series that specifies voltage ripple and noise of"< 350 uVrms/ 2 mVpp"compared to"typ. < 1.5 mV (RMS), < 20 mV (peak-to-peak) (meas.)"for the NGE.)

author: Fixpoint
author_rank: Regular Contributor
timestamp: October 13, 2020, 02:23:18 pm
content: Quote from: RBBVNL9 on October 13, 2020, 01:05:18 pmCome on, when we see education listed first, we know what we are dealing with. Marketing will always name the primary use case first. And OF COURSE they mention labs. I mean -- where else do you use a bench power supply? Definitely not on the road. The mention of labs and system racks is self-evident and just marketing speak because it would be a bad idea to mention ONLY education. They want to make money, of course they also mention other uses. Why not use it in a lab? Sure, it works, that's not a wrong statement, and for many labs it will do a great job. It's just not the *primary* use case.BTW, the RTB2004 is also designed with education in mind. They even have a special education offer.QuoteAgain, marketing speak ... Of course they will say "low ripple", just because it doesn't have high ripple. Which is true, it doesn't. Please let's remember that the NGE is not a bad instrument. And let's be reasonable -- the NGE indeed has low ripple, just not VERY low ripple. There are many PSUs that don't have low ripple, with those you have pretty different numbers than with the NGE.

author: RBBVNL9
author_rank: Frequent Contributor
timestamp: October 13, 2020, 03:40:41 pm
content: Whatever reasons R&S have to write that this device is"Tailored to be used in education, labs and system racks", if they do so, we cannot disqualify someone for using it in a lab.I agree we cannot expect unusually high performance from an instrument when this is not specified. But that does not mean that ‘anything goes’ for a device that is marketed for use in a lab. If justanothername’s unit is indeed jumps up and down by 30 to 40mV, is that OK? And, just suppose, that the jumps are 100mV, would that be OK? Of a full volt jump, is that OK, even when this performance criteria is not specified?I’m not saying I have the wisdom of saying when something is still OK and when it is not, but I cannot blame someone for bringing up the question, or wanting to know whether his of her own unit behaves differently from that of others.

author: switchabl
author_rank: Frequent Contributor
timestamp: October 13, 2020, 04:23:24 pm
content: Without weighing in on the more general discussion: I am not sure that fluctuations <20Hz are completely unspecified. I would think they should not exceed the "programming accuracy" of < 0.1% + 30mV.

author: RBBVNL9
author_rank: Frequent Contributor
timestamp: October 13, 2020, 04:23:37 pm
content: Oh, wait a moment! All this time, we have all been writing that this voltage stability aspect was not specified for this device.But I think that R&S actually DOES specify this!!! Look at the data sheet, page 8:Programming accuracy:Voltage. ± (% of output + offset). < 0.1% + 30 mVSo at 4V output, the output should be within 34 mV from the set value (correct me if I am wrong).If so (and assuming his measurements are OK) then justanothername's unit is on the edge of the specs, perhaps just under, perhaps just above.In the specs, no load condition is indicated, but I think it is reasonable to assume that this specification must be met under load. Would be interested to see this.PS: The data sheet programming accuracy for current, and also specifies the read back accuracy. I also noted that all specs are valid at +23°C (–3°C/+ 7°C) after 30 minutes warm-up time. There is also a lot more small print one might want to read to understand what these specifications mean.

author: RBBVNL9
author_rank: Frequent Contributor
timestamp: October 13, 2020, 04:24:37 pm
content: @switchabl: our posts crossed in cyberspace ;-)

author: RBBVNL9
author_rank: Frequent Contributor
timestamp: October 13, 2020, 05:06:53 pm
content: Repeating the above specs: at 4V output, the output should be within 34 mV from the set value (correct me if I am wrong). So, the output may 'slowly' fluctuate up to 68 mV, if that fluctuation is precisely around the set value. (Fast fluctuations are covered by the stricter ripple and noise specs that apply from 20Hz on.)Just just measured my NGE at 4V with a 2.5A load, out of curiosity. A did a 1 hour, 1 second interval output voltage measurement (using the setup I discussed above). Let us for the sake of the argument suppose this measurement is accurate (do not want to go down this road)... My measurements varied from 37.5mV below the set value to 2.9mV below the set value. (It never goes up to or above the set value.) My results would be about same as the allowed deviation, or a bit above (assuming they are valid for a device under such load).The graphs I see suggest that some kind of switching is going on (some minutes high values, then some minutes low values, and so on).But again, I am not claiming my measurements are in fact accurate. And if they were, we would still need to look at all the fine print in the data sheet...

author: switchabl
author_rank: Frequent Contributor
timestamp: October 13, 2020, 06:14:24 pm
content: It is not stated explicitly (as far as I can see), but I would assume that the programming accuracy is specified with no load. So you would have to allow for another 0.1%+20mV due to load regulation.(At least for the older Agilent power supplies, I remember that the performance verification procedure had you checking the programming accuracy with no load, and then verify load regulation separately.)Overall, the specs of the NGE100 don't look too impressive to me. I don't think I would want one as my go-to bench supply for design work (especially analog). It is definitely not in the same league as the more expensive Keysight E36300 or R&S HMP series (or an old Agilent E363x at that).That being said, for many applications it will still be more than good enough and it packs 3 independent channels with a decent amount of power in a compact box. If you qualify for an education discount the price might be quite attractive as well.

author: Fixpoint
author_rank: Regular Contributor
timestamp: October 13, 2020, 06:37:54 pm
content: Quote from: switchabl on October 13, 2020, 06:14:24 pmYes, that's right, the specs are not "impressive". If impressive specs is what you are looking for, this instrument is not for you.I personally use this instrument because of its usability and because it has 3 channels (which I indeed make use of, depending on the project). I don't care about 10 or 20 mVpp ripple, but I care about usability. And I like the NGE's UI and UX very much. (It's also a good-looking PSU, if that makes sense.) And, of course, it should protect my stuff from the occasional short, which it does very well.I am using it on analog VCO stuff, and for now everything works fine.

author: RBBVNL9
author_rank: Frequent Contributor
timestamp: October 13, 2020, 07:10:44 pm
content: QuoteMmm. That’s an interesting point. I once understood that ripple and noise specs are usually provided for full load (after all, in a classical design, it is under load that capacitors discharge and ripple emerges). Would program accuracy be different in that respect?QuoteNot sure where you take that number from. In the specs, I see that number for "Readback accuracy" but I understand that number to reflect the values shown on the voltmeter on the front panel, but that would be something different.

author: switchabl
author_rank: Frequent Contributor
timestamp: October 13, 2020, 07:46:33 pm
content: I may be wrong. But it seems to be the case for Agilent power supplies. In any case, with datasheets I usually assume that all error sources may add up unless otherwise stated. Arguably if it included everything, we could just call it "output accuracy" and not list load/line regulation at allLoad regulation is listed on p.8 (https://scdn.rohde-schwarz.com/ur/pws/dl_downloads/dl_common_library/dl_brochures_and_datasheets/pdf_1/service_support_30/NGE100B_bro_en_5216_1370_32_v0100_120dpi.pdf)< 0.1% + 20mV for a load change from 10% to 90%.

author: RBBVNL9
author_rank: Frequent Contributor
timestamp: October 13, 2020, 08:19:08 pm
content: QuoteOh yes, you are right, I see that now. Overlooked it. It also has the "±" sign.

author: justanothername
author_rank: Regular Contributor
timestamp: October 27, 2020, 11:21:17 pm
content: Programming accuracy: This is (in my understanding) no specfication that describes the dynamic behavior of the unit. It is what you get in voltage when you set a voltage.I'm thinking about linearity of the DAC, not low frequency noise of the output. So for instance, if you want to set 4V you may get 4.034V because of (shitty) DAC but this should be stable within noise and load regulation specification.Maybe I'm just completely wrong here.It's the accuracy vs precision thing:https://commons.wikimedia.org/wiki/File:Accuracy_and_Precision.svg

author: RBBVNL9
author_rank: Frequent Contributor
timestamp: October 28, 2020, 06:57:45 am
content: @justanother name: this is an interesting thought.Inthis article, the same is explained in the context of a measurement instrument. A recommended read. In analogy with your picture with a target, for a 'perfect' measurement all dots(which are measurements over time) are exactly on the bull's eye.Yet, my interpretation for a PSU is as follows: the provided value explains that we were to connect the perfect meter above to the output of the PSU, then at any time, the readings of that perfect meter would be within the 'inner circle of your target'. This requires:- an internal measurement function in the PSU that is sufficiently accurate to reach that goal,- an internal measurement function in the PSU that is sufficiently precise to reach that goal (one might average a bit over time to facilitate this),- an internal mechanism that is good enough to make the actual output track the internal measurements within the given specification.My take...-

author: kladit
author_rank: Regular Contributor
timestamp: November 10, 2020, 11:03:34 am
content: The NGE100x has a adjustable limit for current and a feature called fuse, which also allows to set a current limit.The difference between these two features is that when a current greater than then the adjusted limitis flowing the current limit feature reduces the voltage to a level that allows a contionous flow ofmaximal the before adjustet current limit, the fuse feature instead switches off the voltage,so no further current can flow.This fuse feature is not well thought to an end.Most circuitry include one or more electrolytic capactior(s) which to get loaded will cause a higher current flow,the so called switch on current,To this or a little greater current the current limit of the power supply has to be adjusted to allow for normalswitch on behaviour of the device under test.But there is no way in the NGE100x to adjust the fuse current afterwards, when the normal steady current of the device under test flows.I want the fuse to protect the circuit most and therefore it is needed to set the fuse current later on to a current valueless than the switch on current.That is not possible with the NGE100x!There are two solutions to solve this.A) The initial value of the fuse is set to the same as the current limit and is allowed to be change later on to another (mostly lesser) value.B) The different (current limit and fuse) current values for are allowed to set first together with a delay time(to allow the switch on current to happen) for the fuse to get active.R&S guys, you know the problem now, I am awaiting for a new firmware.Regards Klaus

author: RBBVNL9
author_rank: Frequent Contributor
timestamp: November 10, 2020, 11:33:03 am
content: @ kladit,A few thoughts:1. The NGE series has a 'fuse delay' setting. In the manual, this is described as"The fuse delay function is intended to ignore the current peaks set above the current limit that occur during the time set in the fuse delay. This prevents the fuse to be triggered in case of a capacitive load."Seems like what you are looking for!2. Alternatively, for the situation you described, you might want to use multiple channels in the NGE (there are three identical channels, after all!). You would set a first channel for the longer time protection (current) values you wish, and a second channel - in parallel - that is capable of suppling the higher current during start-up.3. Moreover, the EasyArb function allows to set different time periods with different current settings.GL!

author: kladit
author_rank: Regular Contributor
timestamp: November 10, 2020, 02:03:36 pm
content: @RBBVNL9The fuse delay is not relative to current limit. It just makes the electronic fuse behave like a slow wire fuse.This is not what I meant. The electronic fuse should switch off the voltage as fast as possible and even for ashort increase of current above the set limit in oder to protect the DUT.Therefore its current limit should be adjustable after the switch on current has happend.I don't think this is too difficult to implement for R&S and would make the NGE a more valuable power supply.

author: RBBVNL9
author_rank: Frequent Contributor
timestamp: November 10, 2020, 02:30:18 pm
content: QuoteAre you sure? I just tried this on my NGE, and while the output is on, I can just change the current at which the fuse trips at any moment to the desired value (note that when the Fuse function is activated, the current values you can set (and which are shown in white font on the display) relate to the fuse tripping value, and not any more to the current limiter value). I checked this with an electronic load, and the fuse behaves exactly like you would expect it to.You can also automate the process with EasyArb. Just tested this as follows:- Activated the Fuse function- Set EasyArb step 1 at 5V, 2A, 5 seconds- Set EasyArb step 2 at 5V, 1A, 100 seconds- Connected an electronic load set at 1.5A- Started the PSU and started EasyArbAnd, indeed, after 5 exactly second, the fuse tripped.

author: kladit
author_rank: Regular Contributor
timestamp: November 10, 2020, 04:42:20 pm
content: @RBBVNL9Question: How can one switch off the fuse function and change the behavoir to current limit only?That means the current stays and the voltage goes down to keep the current the samewith a sinking value of the load resistor.

author: RBBVNL9
author_rank: Frequent Contributor
timestamp: November 10, 2020, 05:00:36 pm
content: Not sure I understand your question. Earlier, you asked:QuoteI think I have shown above how that is done on the NGE.But now your question is:QuoteWhat you describe is the default working mode of the NGE. This is the way this PSU it behaves until you active the Fuse function (fuse trip mode) for a given channel.If your question was meant to be whether you can switch between fuse trip mode and current limit modewhile the channel output is activatedthen my answer would be that, to the best of my knowledge, this is not possible. But I don't see exactly why you would like to do that, and it would not offer the protection of your DUT that you were looking for.

author: kladit
author_rank: Regular Contributor
timestamp: November 10, 2020, 06:44:23 pm
content: @RBBVNL9The reason is i did this ..I switched the power supply on, pressed CH and and adjusted a current.Then I switched on OUTPUT and increased the load current.At the point the load current increased over the adjusted current the voltage decreasedang the numbers got red. Ok , behavior expected.Then I switched OUTPUT off and pressed FUSE and CURRENT and adjusted for lower fuse current.Then I tuned my load to blow the fuse. The word fuse got red and the voltage got switched off. Ok , behavior expected.Then I set my load back, switched CH1 on again, FUSE lights got green again, pressed CURRENT and was able todecrease the current setting to a value lower than my load current and then the fuse 'blowed' again.So you are right and I was wrong. The fuse current is adjustable later on to a lower value thanthe value adjusted for current limit.In other words: as long as the word FUSE shines up the current button adjusts the fuse current and notthe current limit current.But up to now I found no other way to get rid of the FUSE than to switch the NGE100 off and on again.Therefore the question in my last post.It is a little inconvenient to re-adjust the fuse current limit to a higher value every time the fusegot blown and you switch the output on again and then, after the load current of the capacitors has settled,re-adjust it to a lower value again.So my wish to R&S now goes for a adjustable fuse delay time after channel (re-)activation.Thanks for forcing me re-thinking the whole problem.

author: RBBVNL9
author_rank: Frequent Contributor
timestamp: November 10, 2020, 06:55:07 pm
content: Happy to hear this addressed your issue.As to whether you really need to turn of the PSU off altogether in the case you mention, let me check that tomorrow.

author: lucasc
author_rank: Newbie
timestamp: August 17, 2021, 01:49:58 pm
content: Hi @justanothername,What did you end up doing? Did you send it back, or was it something that could be fixed?I'm having the exact same problem and I agree with you that this is not acceptable for a PSU of the level and cost. If this is the expected performance, I'm definitely sending it back. I also noticed that if I move the voltage up and down with the output turned off, the output voltage shows a negative step of about 450mV for about half a second, which is crazy. I've attached the image of the negative step I just mentioned about.Looking forward to your feedback.

author: RBBVNL9
author_rank: Frequent Contributor
timestamp: August 17, 2021, 08:21:54 pm
content: Hello Lucasc,QuoteNever noticed that before, but you are right, I can indeed replicate that. With the output being turned off, it's there every time when you move the voltage setting from 4.10 V down to 4.0 V.Very very weird. This should definitely be corrected!

author: YetAnotherTechie
author_rank: Regular Contributor
timestamp: August 18, 2021, 01:53:49 am
content: Quote from: lucasc on August 17, 2021, 01:49:58 pmCan confirm, V 1.54On channel 1 mine does it from 4.10 to 4.00 and on channels 2 and 3 it's from 4.00 to 3.90.So going back to beginning of the thread, it seems this is a bug related to something internal switching around the 4V setpoint.

author: Gulftown
author_rank: Regular Contributor
timestamp: May 15, 2024, 09:14:44 am
content: Hello,i try to use a NGE103B FW1.57 to aquire charging curves of batteries.Therefore the supply is in constant current mode until the battery is nearly full.When in CC mode the output voltage is jumping up in approx. 100mV steps and not increasing smoothly as expected.So the charging curves are completly useless.Is this a common problem with the regulation of this type of supply, because i cant find anything in the datasheet hinting at such a poor current regulation?Thanks